Poul Erik Hansen's Publications List

Deuterium isotope effects on C-13 and N-15 chemical shifts of intramolecularly hydrogen-bonded enaminocarbonyl derivatives of Meldrum's and Tetronic acid

2011-02-13T13:22:21Z

Secondary deuterium isotope effects on C-13 and N-15 nuclear shieldings in a series of cyclic enamino-diesters and enamino-esters and acyclic enaminones and enamino-esters have been examined and analysed using NMR and DFT (B3LYP/6-31G(d,p)) methods. One-dimensional and two-dimensional NMR spectra of enaminocarbonyl and their deuterated analogues were recorded in CDCl3 and CD2Cl2 at variable temper...

S Ullah, W Zhang, P E Hansen (2010) JOURNAL OF MOLECULAR STRUCTURE 976: 1-3 377-391

SEQUENCE AND STRUCTURAL ANALYSIS OF kappa-CARRAGEENAN-DERIVED OLIGOSACCHARIDES BY TWO-DIMENSIONAL NUCLEAR MAGNETIC RESONANCE1

2011-02-13T13:22:21Z

kappa-Carrageenan was hydrolyzed with mild hydrochloric acid and separated into a series of oligosaccharides, the sequences and structures of which were investigated by double-quantum filtered correlation spectroscopy (DQF-COSY), total correlation spectroscopy (TOCSY), heteronuclear multiple-quantum coherence (HMQC), and heteronuclear multiple-bond correlation (HMBC) techniques, respectively. The ...

W Zhang, M Liu, P E Hansen, G L Yu, B Yang, X Zhao (2010) JOURNAL OF PHYCOLOGY 46: 4 831-838

Trichloromethyl compounds - Natural background concentrations and fates within and below coniferous forests

2011-02-13T13:22:21Z

Pollution with organochlorines has received major attention due to various environmental effects but it is now increasingly recognized that they also take part in biogeochemical cycles and that natural background concentrations exist for several chlorinated compounds We here report the natural occurrence and cycling of organic compounds with a trichloromethyl moiety in common The study areas are t...

C N Albers, P E Hansen, O S Jacobsen (2010) SCIENCE OF THE TOTAL ENVIRONMENT 408: 24 6223-6234

13C-NMR chemical shift databases as a quick tool to evaluate structural models of humic substances.

2011-02-13T13:47:36Z

Christian Nyrop Albers, Poul Erik Hansen, (2010) Open Magnetic Resonance 3: 96-105

Methodological problems in determining TCAA in soils-the discovery of novel natural trichloroacetyl containing compounds and their interference with a common method for determining TCAA in soil and vegetation

2011-02-13T13:22:21Z

Trichloroacetic acid (TCAA) is a pollutant with several sources and is also formed naturally in soil. We show that almost all investigated environmental compartments (soil, soil water, groundwater, spruce needles and throughfall, but not rain) contain compounds, which make false positives in the thermal decarboxylation method often used for determination of TCAA in environmental samples. The compo...

C N Albers, P E Hansen, O S Jacobsen (2010) JOURNAL OF ENVIRONMENTAL MONITORING 12: 3 672-680

Theoretical and NMR Studies of Deuterium Isotopic Perturbation of Hydrogen Bonding in Symmetrical Dihydroxy Compounds

2011-02-13T13:22:21Z

Deuterium equilibrium isotope effects (EIEs) for a cage diol and 2,6-dihydroxyacylaromatics and complexes thereof containing intra- or intermolecular hydrogen bonds have been calculated using harmonic and anharmonic vibrational frequencies using GAussian '03 and the HF, B3LYP, and MP2 levels of theory. The predicted isotope effects have been compared with experimental NMR data, and the origins of ...

D J O'Leary, D D Hickstein, B K V Hansen, P E Hansen (2010) JOURNAL OF ORGANIC CHEMISTRY 75: 5 1331-1342

Cytotoxic Geranylated Xanthones and O-Alkylated Derivatives of alpha-Mangostin

2011-02-13T13:22:21Z

Two new geranylated xanthones, 6-O-methylcowanin (4) and oliverixanthone (5), along with five known compounds, cowanin, rubraxanthone, cowaxanthone, cowanol, and beta-mangostin, have been isolated from the bark of Garcinia oliveri. For comparison of their biological activities, one mono- and seven di-O-alkylated alpha-mangostin derivatives were synthesized from alpha-mangostin. The structures of a...

L D Ha, P E Hansen, O Vang, F Duus, H D Pham, L H D Nguyen (2009) CHEMICAL & PHARMACEUTICAL BULLETIN 57: 8 830-834

The influence of organic matter on sorption and fate of glyphosate in soil - Comparing different soils and humic substances

2011-02-13T13:22:21Z

Soil organic matter (SOM) is generally believed not to influence the sorption of glyphosate in soil. To get a closer look on the dynamics between glyphosate and SOM, we used three approaches: I. Sorption studies with seven purified soil humic fractions showed that these could sorb glyphosate and that the aromatic content, possibly phenolic groups, seems to aid the sorption. II. Sorption studies wi...

C N Albers, G T Banta, P E Hansen, O S Jacobsen (2009) ENVIRONMENTAL POLLUTION 157: 10 2865-2870

NMR of a series of novel hydroxyflavothiones

2011-02-13T13:22:21Z

Alkylated hydroxyflavothiones, namely flavothione, 5-hydroxyflavothione, 5,7-dihydroxyflavothione (chrysinthione), 7-dodecyloxy-5-hydroxyflavothione, 7-butyloxy-5-hydroxyflavothione, 2',3,4',7-tetramethoxy-5-hydroxyflavothione, 3,3',4',7-tetra methoxy-5-hydroxyflavothione, 7-butyloxy-4',5-dihydroxyflavothione and 7-butyloxy-4',5-hydroxyflavanonethione have been synthesized from the corresponding h...

T K P Nguyen, K P P Nguyen, F S Kamounah, W Zhang, P E Hansen (2009) MAGNETIC RESONANCE IN CHEMISTRY 47: 12 1043-1054

Effect of Paraquat and Amyloid-β-peptide on the primary astrocyte metabolism studied by 1H-NMR.

2011-02-13T13:51:01Z

Birgitte Thuesen Olesen, Wei Zhang, Jørgen Clausen, Ole Vang and Poul Erik Hansen, (2009) Open Magn.Reson. J. 2: 880-92

Deuterium isotope effects on N-15 backbone chemical shifts in proteins

2011-02-13T13:22:21Z

Quantum mechanical calculations are presented that predict that one-bond deuterium isotope effects on the N-15 chemical shift of backbone amides of proteins, (1)Delta N-15(D), are sensitive to backbone conformation and hydrogen bonding. A quantitative empirical model for (1)Delta N-15(D) including the backbone dihedral angles, I broken vertical bar and I, and the hydrogen bonding geometry is prese...

J Abildgaard, P E Hansen, M N Manalo, A LiWang (2009) JOURNAL OF BIOMOLECULAR NMR 44: 3 119-126

Untitled

2011-02-13T13:18:33Z

P E Hansen (2009) CURRENT ORGANIC CHEMISTRY 13: 3 216-216

NMR Studies of Hydroxy Schiff Bases

2011-02-13T13:18:33Z

The review covers the use of chemical shifts, isotope effects on chemical shifts and coupling constants in the description of Schiff bases. o-Hydroxy Schiff bases are often tautomeric and special attention is devoted to this feature. Nuclei in question are H-1, C-13, N-15, F-19 and O-17. As well primary as secondary isotope effects are treated. Deuterium isotope effects on C-13 and N-15 chemical s...

P E Hansen, Z Rozwadowski, T Dziembowska (2009) CURRENT ORGANIC CHEMISTRY 13: 2 194-215

Hot Topic : Polyphenols

2011-02-13T13:18:33Z

P E Hansen (2009) CURRENT ORGANIC CHEMISTRY 13: 2 123-123

Characterization of Salt Bridges to Lysines in the Protein G B1 Domain

2011-02-13T13:18:33Z

NMR investigations have been carried out on the B1 domain of protein G. This protein has six lysine residues, of which three are consistently found to form surface-exposed salt bridges in crystal structures, while the other three are not. The N zeta and H zeta chemical shifts of all six lysines are similar and are not affected significantly by pH titration of the carboxylate groups in the protein,...

J H Tomlinson, S Ullah, P E Hansen, M P Williamson (2009) JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 131: 13 4674-4684

Secondary thioamide group deformations in different surroundings : The case of intramolecular N-H center dot center dot center dot N hydrogen bond - An X-ray study combined with theoretical calculations

2011-02-13T13:18:33Z

Structures of several beta-amino-functionalized secondary thioamides capable to form intramolecular hydrogen bond N-H center dot center dot center dot N have been determined by X-ray diffraction and ab initio calculations. Both methods show comparable results for the bond lengths and angles, although the N center dot center dot center dot N distances is slightly longer in the calculated structures...

T Borowiak, G Dutkiewicz, J G Sosnicki, T S Jagodzinski, P E Hansen (2008) JOURNAL OF MOLECULAR STRUCTURE 892: 1-3 438-445

Bioactivities and chemical constituents of a Vietnamese medicinal plant Che Vang, Jasminum subtriplinerve Blume (Oleaceae)

2011-02-13T13:18:33Z

Five crude extracts were made from leaves and stems of Jasminum subtriplinerve Blume (Oleaceae) and investigated for antimicrobial, antioxidant and cytotoxic activities. The extractions were done with petroleum ether, ethyl acetate, ethanol, methanol or water. All extracts exhibited anti-bacterial activity except the water fraction. On the other hand, all extracts exhibit antioxidant activity exce...

D H Ngan, H T C Hoai, L M Huong, P E Hansen, O Vang (2008) NATURAL PRODUCT RESEARCH 22: 11 942-949

Characterization and structural modelling of humic substances in field soil displaying significant differences from previously proposed structures

2011-02-13T13:18:33Z

Humic substances (HS) often are dominant constituents of soil organic matter. In this study 28 fractions of HS were purified and chemically characterized from horizons of three Danish soils differing in texture. A commercial humic acid (HA) was included for comparison. The HS fractions were chemically characterized by CHNS analysis, pH-titration and liquid state C-13-NMR experiments. Amino acids a...

C N Albers, G T Banta, O S Jacobsen, P E Hansen (2008) EUROPEAN JOURNAL OF SOIL SCIENCE 59: 4 693-705

Deuterium isotope effects on C-13 chemical shifts of nitromalonamide

2011-02-13T13:18:33Z

The OH chemical shift of the enol form of nitromalonamide is found at 18.9 ppm both in DMSO-d(6) and in DMF-d(7) indicating a very strong hydrogen bond. The OH chemical shift is insensitive to temperature changes. Contrary to the large OH chemical shift, a small two-bond deuterium isotope effect of 0.135 ppm due to deuteration at the OH position is found at the enolic carbon. This is confirmed by ...

P E Hansen (2008) MAGNETIC RESONANCE IN CHEMISTRY 46: 8 726-729

Effect of Different Humic Substances on the Fate of Diuron and Its Main Metabolite 3,4-Dichloroaniline in Soil

2011-02-13T13:18:33Z

Humic substances (HS) are the dominant constituents of soil organic matter (SOM). The interactions between the phenylurea herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron) and several HS fractions, purified from various soil horizons, were studied. One commercial humic acid (HA) was included for comparison. Diuron was shown to adsorb significantly, but reversibly, to purified HA while sor...

C N Albers, G T Banta, P E Hansen, O S Jacobsen (2008) ENVIRONMENTAL SCIENCE & TECHNOLOGY 42: 23 8687-8691

Intramolecular Hydrogen Bonding of 5-Acyl-3-methylrhodanines

2011-02-13T13:18:33Z

A series of 5-acyl-3-methylrhodanines have been synthesized. The structures of those are described using H-1 and C-13 NMR, deuterium isotope effects on C-13 chemical shifts and DFT, calculations. The compounds exist as exocyclic enols with intramolecular hydrogen bonds to the C = ONCH3 oxygen. No signs of enhanced mesoionic character were found.

L B Smith, P E Hansen (2008) ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS 222: 8-9 1213-1223

Secondary thioamide group deformations in different surroundings : The case of intramolecular N-H center dot center dot center dot N hydrogen bond - An X-ray study combined with theoretical calculations

2011-02-13T13:19:26Z

Conformational and tautomeric eccentricities of 2-acetyl-1,8-dihydroxynaphthalenes

2011-02-13T13:35:45Z

Tautomerism in aromatic systems with oxygen substitutents is rare. This is investigated in 2-acetyl-1,8-dihydroxy-3,6-dimethylnaphthalene (1) and in 2,7-diacetyl-1,8-dihydroxy-3,6-dimethylnaphthalene (2). The tautomeric nature of 2-acetyl-1,8-dihydroxy-3.6-dimethylnaphthalene is supported by long-range hydrogen-hydrogen coupling between the OH-1 and the OH-8 and by the isotope effects on C-13 caus...

P E Hansen, F S Kamounah, B K V Hansen, J Spanget-Larsen (2007) MAGNETIC RESONANCE IN CHEMISTRY 45: 2 106-117

Monothiodibenzoylmethane : Structural and vibrational assignments

2011-02-13T13:35:45Z

The vibrational structure of the title compound (1,3-diphenyl-3-thioxopropane-1-one, TDBM) was studied by a variety of experimental and theoretical methods. The stable ground state configuration of TDBM was investigated by infrared (IR) absorption measurements in different media, by linear dichroism (LD) polarization spectroscopy of samples partially aligned in a stretched polymer matrix, and by R...

B K V Hansen, A Gorski, Y Posokhov, F Duus, P E Hansen, J Waluk, J Spanget-Larsen (2007) VIBRATIONAL SPECTROSCOPY 43: 1 53-63

A spectrochemometric approach to tautomerism and hydrogen-bonding in 3-acyltetronic acids

2011-02-13T13:35:45Z

3-Acyltetronic acids bearing different 3- and 5-substituents have been examined focussing on tautomerism and inter- and intramolecular hydrogen-bonding properties of these beta,beta'-tricarbonyl compounds in solution as well as in the solid state. Spectroscopic methods like NMR, IR, Raman-spectroscopy as well as X-ray diffractometry and MAS-NMR for the solid state have been applied. In a solution ...

J P Hofmann, F Duus, A D Bond, P E Hansen (2006) JOURNAL OF MOLECULAR STRUCTURE 790: 1-3 80-88

Preparation and structural characterization of a new class of stable thioketones : ortho-hydroxythioacetophenones

2011-02-13T13:35:45Z

ortho-Hydroxythioacetophenone and four structurally related ortho-hydroxyaryl methyl thioketones have been prepared from the corresponding ketones by reaction with gaseous H2S and HCl in ethanol under strictly controlled reaction conditions. The remarkable stability of the new monomeric thioketones seems to be due to a strong intramolecular O-H center dot center dot center dot S=C hydrogen bonding...

T T Nguyen, T N Le, P E Hansen, F Duus (2006) TETRAHEDRON LETTERS 47: 47 8433-8435

Synthesis and characterization of nickel-, palladium- and platinum(II) complexes of three o,o '-dihydroxydiarylazo dyes : Determination of the coordination geometry of this comprehensive series of tridentate diaryl dye complexes by combining results from NMR and X-ray experiments with theoretical ab initio calculations

2011-02-13T13:35:45Z

The syntheses of the square-planar platinum(II) complexes [Pt(L)(tba)] (L = 5,5'-dichloro-2,2'-dihydroxyazobenzenate (dhab), (5-chloro-2-hydroxyphenylazo)-3-oxo-N-phenylbutanamidate (hpab) or (5-chloro-2-hydroxyphenylazo)-2-naphtholate (hpan) and (tba) = tributylamine) is reported, together with those of the complete set of analogous complexes [M(L)(py)] (M = nickel(II), palladium(II), platinum(II...

J Abildgaard, P E Hansen, J Josephsen, B K V Hansen, H O Sorensen, S Larsen (2006) INORGANICA CHIMICA ACTA 359: 14 4493-4502

Photochromism and polarization spectroscopy of p-methyl(thiobenzoyl) acetone

2011-02-13T13:35:45Z

Photochromism of p-methyl(thiobenzoyl) acetone (1) has been studied in argon and xenon cryogenic matrices. Application of linearly polarized fight to induce the phototransformation resulted in partial alignment of both the initial structure and the photochromic product. Different orientations were achieved by using irradiation wavelengths corresponding to differently polarized electronic transitio...

A Gorski, Y Posokhov, B K V Hansen, J Spanget-Larsen, J Jasny, F Duus, P E Hansen, J Waluk (2006) CHEMICAL PHYSICS 328: 1-3 205-215

NMR Studies of Compounds with Intramolecular Hydrogen bonds

2011-02-14T10:31:48Z

P.E. Hansen (2006) Isotope Effects in Chemistry and Biology

Flavonoid content in Vietnamese Tea

2011-02-14T08:38:18Z

Poul Erik Hansen, Huynh Hoa Thi Troung, Ngoc Son Chu Pham, (2006) Polyphenols Comm., : 403-4

Tautomerism of sterically hindered Schiff bases. Deuterium isotope effects on C-13 chemical shifts

2011-02-13T13:36:15Z

A series of sterically hindered o-hydroxy Schiff bases derived from o-hydroxyaceto- and benzophenones with very short intramolecular hydrogen bonds were described qualitative and quantitatively by deuterium isotope effects on C-13 chemical shift, (n)Delta C(XD), (n)Delta F(XD), (1)J(N,H) coupling constants, delta NCH3 chemical shifts and UV spectra. All the investigated compounds are found to be t...

A Filarowski, A Koll, M Rospenk, I Krol-Starzomska, P E Hansen (2005) JOURNAL OF PHYSICAL CHEMISTRY A 109: 20 4464-4473

Schiff bases of gossypol : an NMR and DFT study

2011-02-13T13:36:15Z

Schiff bases of gossypol with benzylamine, methylamine, 4-aminoacetophenone and 4-fluoroaniline have been synthesized and characterized by NMR spectroscopy. All the Schiff bases of gossypol are in the enamine form according to (3)J(HC,NH) and (1)J(,H) coupling constants. The spectra are basically unchanged by change of solvent (CD2Cl2, THF-d(8) and CD3OD) and by variation of temperature. For the d...

Q T That, K P P Nguyen, P E Hansen (2005) MAGNETIC RESONANCE IN CHEMISTRY 43: 4 302-308

New deuterium isotope effects on C-13 and F-19 chemical shifts across intramolecular hydrogen bonds of non-resonance assisted systems

2011-02-13T13:36:15Z

A series of thioanilides and corresponding anilides, some of which contain fluorinated phenyl rings, have been synthesized as model compounds. They all contain rather strong intramolecular hydrogen bonds. the strength of which varies. Deuterium isotope effects on F-19 and C-13 chemical shifts due to deuteriation at the NH proton show interesting new long-range isotope effects on chemical shifts th...

J G Sosnicki, P E Hansen (2005) TETRAHEDRON LETTERS 46: 5 839-842

Factor analysis of deuterium isotope effects on C-13 NMR chemical shifts in Schiff bases

2011-02-13T13:35:45Z

We have analyzed deuterium isotope effects on C-13 chemical shifts in a series of o-hydroxy Schiff bases by applying factor analysis. Two orthogonal factors were obtained that explain about 80 and 10% of the variance of the data. The numerical values of these factors can be related to H-1 NMR chemical shifts of the proton involved in the intramolecular bonds delta(XH) (X=O or N). Such a relation a...

P M Dominiak, A Filarowski, P E Hansen, K Wozniak (2005) CHEMISTRY-A EUROPEAN JOURNAL 11: 16 4758-4766

Steric compression and twist in o-hydroxy acyl aromatics with intramolecular hydrogen bonding

2011-02-13T13:36:15Z

A series of o-hydroxy acyl aromatics of the type 1,3-diacetyl-2,4,6-trihydroxybenzene (1), 6-methoxy-1,3-diacetyl-2,4-dihydroxy- (2) 2,4,6-trihydroxy- 1,3,5-triacetylbenzene (3) and I -acetyl-2-naphthol (4) have been investigated by means of single crystal X-ray diffraction, solution and solid state NMR spectroscopy and theoretical calculations. The structures of 1 and 2 exhibit interesting hydrog...

P E Hansen, S Bolvig, K Wozniak (2005) JOURNAL OF MOLECULAR STRUCTURE 749: 1-3 155-168

Fast preparation of dihydrocyclocitral from citronellal under solventless microwave irradiation

2011-02-13T13:35:45Z

Dihydrocyclocitral, a useful reagent in organic synthesis, has been synthesized in high yield and with high stereo selectivity from citronellal under microwave irradiation in two steps, involving acetic anhydride under base catalysis, then p-toluenesulfonic acid adsorbed on silica gel under solventless conditions (80% yield, reaction time 22 min). (c) 2005 Elsevier Ltd. All rights reserved.

N N Doan, T N Le, P E Hansen, F Duus (2005) TETRAHEDRON LETTERS 46: 39 6749-6751

Variable-temperature NMR study of the enol forms of benzoylacetones

2011-02-13T13:35:45Z

The enol forms of the beta-diketones, benzoylacetones, have been studied using long-range carbon-hydrogen couplings involving the chelate OH proton, (OH)-H-1 chemical shifts, C-13 chemical shifts and deuterium isotope effects on C-13 chemical shifts. Studies were done in the temperature range from 268 to 181 K. The compounds are shown to be tautomeric, in opposition to a more symmetrical, delocali...

E V Borisov, E V Skorodumov, V M Pachevskaya, P E Hansen (2005) MAGNETIC RESONANCE IN CHEMISTRY 43: 12 992-998

Phosphate pool dynamics in the arbuscular mycorrhizal fungus Glomus intraradices studied by in vivo P-31 NMR spectroscopy

2011-02-13T13:36:44Z

Polyphosphate (polyp) is presumably central to phosphate (P) metabolism of arbuscular mycorrhizal (AM) fungi, but its synthesis, location and chain lengths are poorly characterized. Here, we applied noninvasive and nondestructive nuclear magnetic resonance (NMR) spectroscopy to obtain novel information on AM fungal polyp. In Vivo P-31 NMR spectroscopy was used to characterize polyp and other P poo...

N Viereck, P E Hansen, I Jakobsen (2004) NEW PHYTOLOGIST 162: 3 783-794

Temperature coefficient of NH chemical shifts of thioamides and amides in relation to structure

2011-02-13T13:36:15Z

NH chemical shift temperature coefficients have been measured in a large series of N-substituted-3-piperidinethiopropionamides in which the (NN)-N-... distances are short but of varied length, as well as in a couple of the corresponding amides and in some simpler amides and thioamides. Geometries are calculated by means of ab initio DFT methods. The N-substituted-3-piperidinethiopropionamides show...

J G Sosnicki, P E Hansen (2004) JOURNAL OF MOLECULAR STRUCTURE 700: 1-3 91-103

Theoretical, structural, vibrational, NMR, and thermal evidence of the inter- versus intramolecular hydrogen bonding in oxamides and thiooxamides

2011-02-13T13:36:44Z

This contribution describes the study of hydrogen bonding in secondary oxamides, monothiooxamides, and dithiooxamides by ab initio calculations, X-ray diffractions, NMR spectra, thermal analysis, and variable-temperature infrared and Raman spectroscopy. The results can all be interpreted as a function of the change in the strength and the nature of the hydrogen bonding by substituting oxygen for s...

H O Desseyn, S P Perlepes, K Clou, N Blaton, B J Van der Veken, R Dommisse, P E Hansen (2004) JOURNAL OF PHYSICAL CHEMISTRY A 108: 24 5175-5182

NMR structure determination of a modified DNA oligonucleotide containing a new intercalating nucleic acid

2011-02-13T13:36:44Z

The intercalating nucleic acid (INA) presented in this paper is a novel 1-O-(1-pyrenylmethyl)glycerol DNA intercalator that induces high thermal affinity for complementary DNA. The duplex examined contained two INA intercalators, denoted X, inserted directly opposite each other: d(C(1)T(2)C(3)A(4)A(5)C(6)X(7)C(8)A(9)A(10)G(11)C(12)T(13)):d(A(14)G(15) C(16)T(17)-T(18)G(19)X(20)G(21)T(22)T(23)G(24)A...

C B Nielsen, M Petersen, E B Pedersen, P E Hansen, U B Christensen (2004) BIOCONJUGATE CHEMISTRY 15: 2 260-269

The intramolecular hydrogen bond in ortho-hydroxy acetophenones

2011-02-13T13:36:15Z

The crystal structures of two ortho-hydroxy ketones (5-chloro-2-hydroxyacetophenone (I K) and 3,5-dichloro-2-hydroxyacetophenone (II K)) have been determined with X-ray diffraction at 100 K. A comparison of steric effects on properties of pseudoaromatic hydrogen bonds in ortho-hydroxy acetophenone and ortho-hydroxy ketimines have been carried out with the application of crystallographic data. Nucl...

A Filarowski, A Koll, A Kochel, J Kalenik, P E Hansen (2004) JOURNAL OF MOLECULAR STRUCTURE 700: 1-3 67-72

Thioacetylacetone : Structural and vibrational assignments

2011-02-13T13:36:44Z

Thioacetylacetone and its variously deuterated isotopomers have been investigated using electronic and vibrational spectroscopy combined with quantum chemical calculations. Thioacetylacetone is known for its photochromic properties, but the structures of the initial and final forms have been the subject of a long debate. Analysis of the IR spectra recorded in low-temperature argon and xenon matric...

Y Posokhov, A Gorski, J Spanget-Larsen, F Duus, P E Hansen, J Waluk (2004) CHEMPHYSCHEM 5: 4 495-502

Hydrogen bonds in ''push-pull'' enamines

2011-02-13T13:36:15Z

A comparison of hydrogen bond strengths in various enamines was made by monitoring the differential shifts Deltadelta(X) as the difference of NMR chemical shifts between E and Z forms of the nuclei directly involved in hydrogen bonding, i.e., X = N-15, H-1, O-17 atoms. The interpretation of these differential values was aided by ab initio calculations and X-ray derived geometric parameters for sel...

L Kozerski, B Kwiecien, R Kawecki, Z Urbanczyk-Lipkowska, W Bocian, E Bednarek, J Sitkowski, J Maurin, L Pazderski, P E Hansen (2004) NEW JOURNAL OF CHEMISTRY 28: 12 1562-1567

Structural Studies of a Series of Acetylated Polyphenols and Schiff Bases thereof all with Intramolecular Hydrogen Bonds using Deuterium Isotope Effects on 13C NMR Chemical Shifts, PCA methods, X-ray and Ab Initio Calculations.

2011-02-14T08:36:15Z

Poul Erik Hansen, (2004) Polyphenols Comm. : 37-38

Studies based on deuterium isotope effect on C-13 chemical shifts

2011-02-13T13:36:15Z

T Dziembowska, P E Hansen, Z Rozwadowski (2004) PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 45: 1-2 1-29

Characterisation of the PT-form of o-hydroxy acylarornatic Schiff bases by NMR spectroscopy and DFT calculations

2011-02-13T13:36:15Z

A series of o-hydroxy Schiff bases showing tautomerism to a varying degree are investigated together with compounds totally at the proton transfer form (enamines). Deuterium isotope effects on C-13 chemical shifts are measured at different temperatures. Structural features determining the equilibrium constants are discussed. DFT calculations are done in order to obtain structures. Schiff bases der...

P E Hansen, A Filarowski (2004) JOURNAL OF MOLECULAR STRUCTURE 707: 1-3 69-75

Multiple binding modes of the camptothecin family to DNA oligomers

2011-02-13T13:36:15Z

The binding constants of camptothecin, topotecan and its lactone ring-opened carboxylate derivative to DNA octamers were measured by UV and NMR spectroscopy. The self-association of topotecan (TPT) was also measured. The carboxylate form of TPT binds in the same way as the lactone, but more weakly. Titration of TPT into d(GCGATCGC)(2) shows a preferred location stacked onto the terminal G1 base. H...

W Bocian, R Kawecki, E Bednarek, J Sitkowski, A Pietrzyk, M P Williamson, P E Hansen, L Kozerski (2004) CHEMISTRY-A EUROPEAN JOURNAL 10: 22 5776-5787

Exploring symbiotic nitrogen fixation and assimilation in pea root nodules by in vivo N-15 nuclear magnetic resonance spectroscopy and liquid chromatography-mass spectrometry

2011-02-13T13:36:44Z

Nitrogen (N) fixation and assimilation in pea (Pisum sativum) root nodules were studied by in vivo N-15 nuclear magnetic resonance (NMR) by exposing detached nodules to N-15, via a perfusion medium, while recording a time course of spectra. In vivo P-31 NMR spectroscopy was used to monitor the physiological state of the metabolically active nodules. The nodules were extracted after the NMR studies...

A M Scharff, H Egsgaard, P E Hansen, L Rosendahl (2003) PLANT PHYSIOLOGY 131: 1 367-378

Magnetic susceptibility : Solutions, emulsions, and cells

2011-02-13T13:36:44Z

Differences in magnetic susceptibility between various compartments in heterogeneous samples can introduce unanticipated complications to NMR spectra. On the other hand, an understanding of these effects at the level of the underlying physical principles has led to the development of several experimental techniques that provide data on cellular function that are unique to NMR spectroscopy. To illu...

P W Kuchel, B E Chapman, W A Bubb, P E Hansen, C J Durrant, M P Hertzberg (2003) CONCEPTS IN MAGNETIC RESONANCE PART A 18A: 1 56-71

Solution and solid state C-13 NMR and X-ray studies of genistein complexes with amines. Potential biological function of the C-7, and C-4 '-OH groups

2011-02-13T13:37:19Z

Parent genistein and its new amine complexes with morpholine and piperazine were studied comparatively in the solid and liquid states by X-ray crystallography and C-13 and N-15 NMR spectroscopy. Biochanine A and its complexes were used as reference. Secondary deuterium isotope effects on C-13 chemical shifts in solution were studied in parent isoflavones and their morpholine and piperazine complex...

L Kozerski, B Kamienski, R Kawecki, Z Urbanczyk-Lipkowska, W Bocian, E Bednarek, J Sitkowski, K Zakrzewska, K T Nielsen, P E Hansen (2003) ORGANIC & BIOMOLECULAR CHEMISTRY 1: 20 3578-3585

Isolation, characterization, and quantitative analysis of microviridin J, a new Microcystis metabolite toxic to Daphnia

2011-02-13T13:36:44Z

This paper describes the purification and characterization of microviridin J, a newly discovered metabolite of Microcystis that causes a lethal molting disruption in Daphnia spp., upon ingestion of living cyanobacterial cells. Microviridin J consists of an acetylated chain of 13 amino acids arranged in three rings and two side chains. Unlike other known isoforms of microviridin, microviridin J con...

T Rohrlack, K Christoffersen, P E Hansen, W Zhang, O Czarnecki, M Henning, J Fastner, M Erhard, B A Neilan, M Kaebernick (2003) JOURNAL OF CHEMICAL ECOLOGY 29: 8 1757-1770

NMR and IR Spectroscopy of Phenols.

2011-02-14T10:27:21Z

P.E. Hansen and J.Spanget-Larsen (2003) Phenols 333-393

Solution and solid state C-13 NMR and X-ray studies of genistein complexes with amines. Potential biological function of the C-7, and C-4 '-OH groups

2011-02-13T13:36:44Z

One-bond C-H coupling constants of acetyl groups as possible monitors of CH hydrogen bonds and electric field effects

2011-02-13T13:36:44Z

C-H coupling constants of acetyl groups of a series of substituted 2-hydroxyacetophenones have been measured. These (1)J(C,H) couplings are then intercompared and compared to acetophenone in order to elucidate the cause of the variation. Structures are calculated using ab initio DFT methods. A comparison of 2-hydroxyacetophenone and acetophenone shows an increase of similar to0.5 Hz. An OR group i...

P E Hansen (2003) POLISH JOURNAL OF CHEMISTRY 77: 11 1683-1691

The application of high-performance liquid chromatography humic acid columns in determination of K-oc of polycyclic aromatic compounds

2011-02-13T13:36:44Z

An improvement of a method for determination of the distribution coefficient for polycyclic aromatic compounds (PAC) between organic carbon and water (K-proportional to) by high-performance liquid chromatography (HPLC) is presented in this paper. By use of silica-based HPLC columns with chemically immobilized humic acid (Aldrich, Zigma-Aldrich, Taufkirchen, Germany), the retention of PAC to humic ...

K E N Jonassen, T Nielsen, P E Hansen (2003) ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 22: 4 741-745

Intrinsic deuterium isotope effects on NMR chemical shifts of hydrogen bonded systems

2011-02-13T13:37:55Z

This mini review describes intrinsic deuterium isotope effects on C-13 chemical shifts of rigid hydrogen bonded compounds primarily in solution. The steric effects of intramolecularly hydrogen bonded compounds are dissected into different interactions leading either to steric compression or to steric twist. One-bond isotope effects involving CH(D) bonds are analyzed in terms of substituent effects...

P E Hansen (2002) NUKLEONIKA 47: S37-S42

Solution structure of the eukaryotic pore-forming cytolysin equinatoxin II : Implications for pore formation

2011-02-13T13:37:55Z

Sea anemones produce a family of 18-20 kDa proteins, the actinoporins, that lyse cells by forming pores in cell membranes. Sphingomyelin plays an important role in their lytic activity, with membranes lacking this lipid being largely refractory to these toxins. The structure of the actinoporin equinatoxin II in aqueous solution, determined from NMR data, consists of two short helices packed agains...

M G Hinds, W Zhang, G Anderluh, P E Hansen, R S Norton (2002) JOURNAL OF MOLECULAR BIOLOGY 315: 5 1219-1229

The tautomeric equilibrium and stereochemistry of beta-sulfonyl enamines

2011-02-13T13:37:55Z

Compounds of three groups of parent secondary aliphatic beta-sulfonyl enamines, unsubstituted or with an alkyl substituent in the alpha or beta positions, have been studied. The beta-sulfonyl enamines are found in equilibria between the E and Z enamine and imine forms in varying amounts in CDCl3 solution. H-1, C-13 and N-15 data were acquired and used for the assignment of the three species in sol...

L Kozerski, B Kwiecien, P Krajewski, R Kawecki, E Bednarek, J Sitkowski, W Bocian, W Kozminski, P E Hansen (2002) NEW JOURNAL OF CHEMISTRY 26: 8 1060-1069

Deuterium isotope effects on N-15, C-13 and H-1 chemical shifts of proton sponges

2011-02-13T13:37:55Z

Deuterium isotope effects on N-15, C-13 and H-1 chemical shifts have been measured in the protonated forms of DMAN, 4-bromo, 4-picryl, 4-nitro and 2- and 2,7-chloro derivatives. Structures have been geometry optimised using BPW91/6-31(d)G density functional theory (DFT) methods and show good correspondence to experimental X-ray data. N-15, C-13 and H-1 chemical shifts are calculated using GIAO/DFT...

E Grech, J Klimkiewicz, J Nowicka-Scheibe, M Pietrzak, W Schilf, A F Pozharski, V A Ozeryanskii, S Bolvig, J Abildgaard, P E Hansen (2002) JOURNAL OF MOLECULAR STRUCTURE 615: 1-3 121-140

Characterisation of humic materials of different origin : A multivariate approach for quantifying the latent properties of dissolved organic matter

2011-02-13T13:37:55Z

The inherent chemical properties of eight different dissolved organic matters (DOMs) originating from soil, surface and groundwater have been analysed. The samples consist of isolated fulvic acids (FA), humic acids (HA), and humic substances (HS), i.e. natural mixtures containing a humic and a fulvic fraction. The humic substances have been characterised by elemental analysis, size exclusion chrom...

M Thomsen, P Lassen, S Dobel, P E Hansen, L Carlsen, B B Mogensen (2002) CHEMOSPHERE 49: 10 1327-1337

Reverse quantitative structure-activity relationship for modelling the sorption of esfenvalerate to dissolved organic matter - A multivariate approach

2011-02-13T13:37:55Z

The sorption of the pyrethroid, esfenvalerate, to the dissolved and/or dispersed fraction of eight different natural humic compounds has been investigated. The dissolved organic matters (DOMs) included in this study originate from ground water, soil pore water, and surface waters. Sorption was modelled at DOM concentration levels where equilibrium partitioning of esfenvalerate between DOM and the ...

M Thomsen, S Dobel, P Lassen, L Carlsen, B B Mogensen, P E Hansen (2002) CHEMOSPHERE 49: 10 1317-1325

Synthesis of the N-allylthioamide derivatives of cyclic oxo- and dioxo- acids and their cyclization to the derivatives of 4,5-dihydrothiazole

2011-02-13T13:38:21Z

The title N-allylthioamides (1a-f) were synthesized in the reaction of allyl isothiocyanate with enamines (1a-c) and 1,3-diketones (1d-f), respectively carried out in an acetonitrile solution in the presence of DBU. When treated with the bromine-dioxane complex or with iodine, they underwent cyclization to the corresponding derivatives of 4,5-dihydrothiazole (2a-g). NMR spetroscopy made it possibl...

A Wesolowska, T S Jagodzinski, J G Sosnicki, P E Hansen (2001) POLISH JOURNAL OF CHEMISTRY 75: 3 387-400

A nicked duplex decamer DNA with a PEG(6) tether

2011-02-13T13:38:21Z

A dumbbell double-stranded DNA decamer tethered with a hexaethylene glycol linker moiety (DDSDPEG), with a nick in the centre of one strand, has been synthesised. The standard NMR methods, E.COSY, TOCSY, NOESY and HMQC, were used to measure H-1, P-31 and T-1 spectral parameters, Molecular modelling using rMD-simuiated annealing was used to compute the structure. Scalar couplings and dipolar contac...

L Kozerski, A P Mazurek, R Kawecki, W Bocian, P Krajewski, E Bednarek, J Sitkowski, M P Williamson, A J G Moir, P E Hansen (2001) NUCLEIC ACIDS RESEARCH 29: 5 1132-1143

Inositol phosphates from barley low-phytate grain mutants analysed by metal-dye detection HPLC and NMR

2011-02-13T13:38:21Z

Inositolphosphates from barley low-phytate grain mutants and their parent variety were analysed by metal-dye detection HPLC and NMR. Compound assignment was carried out by comparison of retention times using a chemical hydrolysate of phytate [Ins(1,2,3,4,5,6)P-6] as a reference; Co-inciding retention times indicated the presence of phytate, D/L-Ins(1,2,3,4,5)P-5, Ins(1,2,3,4,6)P-6, D/L-(1,2,4,5,6)...

F Hatzack, F Hubel, W Zhang, P E Hansen, S K Rasmussen (2001) BIOCHEMICAL JOURNAL 354: 473-480

Reactivity and diastereoselectivity of Michael additions of amines to achiral alpha,beta-unsaturated thioamides

2011-02-13T13:37:55Z

Heterocyclic, aliphatic amines add to acyclic and cyclic alpha,beta -unsaturated thioamides yielding beta -amino-functionalized derivatives. In the case of cyclic acceptors, the formation of both kinetic and thermodynamically controlled products is observed. Tailoring of cis or trans products is thus possible. A mechanism for the addition to cyclic acceptors is proposed and evidence presented to s...

J G Sosnicki, T S Jagodzinski, P E Hansen (2001) TETRAHEDRON 57: 41 8705-8718

NMR study of proton transfer equilibrium in Schiff bases derived from 2-hydroxy-1-naphthaldehyde and 1-hydroxy-2-acetonaphthone. Deuterium isotope effects on C-13 and N-15 chemical shifts

2011-02-13T13:37:55Z

The proton transfer equilibrium in series of Schiff bases derived from 2-hydroxy-1-naphthaldehyde and 1-hydroxy-2-acetonaphthone were measured by means of H-1, C-13 and N-15 NMR spectra and deuterium isotope effects on C-13 and N-15 chemical shifts at variable temperature and in different solvents. The latter made it possible to investigate a broad range of equilibrium positions. All compounds exi...

T Dziembowska, Z Rozwadowski, A Filarowski, P E Hansen (2001) MAGNETIC RESONANCE IN CHEMISTRY 39: S67-S80

Sorption of polycyclic aromatic compounds to humic and fulvic acid HPLC column materials

2011-02-13T13:37:55Z

Two different humic acids (HA) and a fulvic acid (FA) were chemically immobilized to a high performance liquid chromatography (HPLC) silica column material. The immobilization was performed by binding amino groups in HA/FA to the free aldehyde group in hlutardialdehyde attached to the silica gel. The HPLC column materials were compared with a blank column material made by applying the same procedu...

K Kollist-Siigur, T Nielsen, C Gron, P E Hansen, C Helweg, K E N Jonassen, O Jorgensen, U Kirso (2001) JOURNAL OF ENVIRONMENTAL QUALITY 30: 2 526-537

H-1 NMR of compounds with low water solubility in the presence of erythrocytes : effects of emulsion phase separation

2011-02-13T13:38:21Z

When lipophilic compounds like diethyl phthalate (DEP) were added to water, two sets of resonances appeared in the H-1 NMR spectrum, whereas when added in concentrations above similar to3.5 mM to erythrocytes in a high haematocrit suspension, only one set of resonances was observed at the low-frequency position. The appearance of one set of resonances at lower frequency was found to be common to a...

P E Hansen, U Skibsted, J Nissen, C D Rae, P W Kuchel (2001) EUROPEAN BIOPHYSICS JOURNAL WITH BIOPHYSICS LETTERS 30: 1 69-74

Stable ion study of regioisomeric carboxonium-substituted pyrenium ions : Directive effects, charge delocalization mode, and conformational aspects

2011-02-13T13:38:41Z

Regioisomeric monoacyl- and monobenzoyl-substituted pyrenes are diprotonated in FSO3H . SbF5 (4:1)/SO2ClF to give persistent carboxonium-pyrenium dications, whereas diacetyl- and dibenzoyl-pyrenes are diprotonated to give dicarboxonium dications. The resulting dications were studied by low-temperature NMR at 500 MHz. Conformational aspects of the carboxonium group in various regioisomers are addre...

K K Laali, T Okazaki, P E Hansen (2000) JOURNAL OF ORGANIC CHEMISTRY 65: 12 3816-3828

Variable temperature H-1 and C-13 NMR spectroscopic investigation of the enol-enethiol tautomerism of beta-thioxoketones. Isotope effects due to deuteron chelation

2011-02-13T13:38:41Z

A chemical shift vs. temperature analysis of beta-thioxoketones has been performed for the four beta-thioxoketones, thioacetylacetone (1), benzoylthioacetone (2), thiobenzoylacetone (3) and monothiodibenzoylmethane (4), to test this method as a general way of obtaining the individual chemical shifts of tautomers involved in tautomeric equilibria. Both C-13 and chelate H-1 resonances far 1 and 2 sh...

B Andresen, F Duus, S Bolvig, P E Hansen (2000) JOURNAL OF MOLECULAR STRUCTURE 552: 45-62

Deuterium isotope effects of o-hydroxythioamides, (2)Delta-thiazolines and 5-acyl-2-thiobarbituric acids

2011-02-13T13:39:04Z

Deuterium isotope effects on C-13 chemical shifts are studied in a series of o-hydroxythioamides, (2)Delta-thiazolines and enolic 5-acyl-2-thiobarbituric acids. Novel 2-hydroxy-1-thiocarboxamide naphthalenes show steric isotope effects of opposite sign to those observed in 2-hydroxy-1-acetylnaphthalenes and pyrenes. The o-hydroxyaromatic (2)Delta-thiazolines show tautomeric behaviour and according...

P E Hansen, F Duus, R Neumann, A Wesolowska, J G Sosnicki, T S Jagodzinski (2000) POLISH JOURNAL OF CHEMISTRY 74: 3 409-420

Isotope effects on chemical shifts of proteins and peptides

2011-02-13T13:39:04Z

Isotope effects on chemical shifts, (n)Delta(13)C(D), (n)Delta(1)H(D), (1)Delta(15)N(D) and (1)Delta(13)C(O-18), and solvent isotope effects in proteins are reviewed and references are provided to related cases. The isotope effects included are motivated by the effects occurring in perdeuterated proteins and effects of C-13 and N-15 labelling combined with effects of an H2O-D2O mixture. The focus ...

P E Hansen (2000) MAGNETIC RESONANCE IN CHEMISTRY 38: 1 1-10

Application of the HECADE method to the measurement of long-range heteronuclear C-13,H-1 spin-spin coupling constants in tautomeric beta-sulfonylenamines

2011-02-13T13:38:41Z

The applicability of HECADE approach to the measurement of C-13, 1 long-range coupling constants, which was difficult to achieve by other methods, is demonstrated. The coupling magnitudes obtained allow the qualitative characterization of rotational degrees of freedom in all isomers of the beta-sulfonylenamines studied in terms of the prevailing conformation contribution to conformational averagin...

W Kozminski, E Bednarek, W Bocian, J Sitkowski, P E Hansen, B Kwiecien, L Kozerski (2000) MAGNETIC RESONANCE IN CHEMISTRY 38: 10 839-844

Isotope effects on chemical shifts as an analytical tool in structural studies of intramolecular hydrogen bonded compounds

2011-02-13T13:39:04Z

Isotope effects on chemical shifts of intramolecularly hydrogen bonded systems are reviewed. The effects are conveniently divided into localized (intrinsic) and equilibrium isotope effects. The review covers both primary and secondary isotope effects on chemical shifts. For the localized one ii is very important to distinguish between RAHB and non-RAHB types. For the RAHB systems the OH group is s...

S Bolvig, P E Hansen (2000) CURRENT ORGANIC CHEMISTRY 4: 1 19-54

Primary tritium and deuterium isotope effects on chemical shifts of compounds having an intramolecular hydrogen bond

2011-02-13T13:38:41Z

The primary deuterium and tritium isotope effects, delta(XH) - delta(XD/T), were measured for 55 compounds having one or more intramolecular hydrogen bonds. The primary isotope effects were measured at various temperatures. For compounds displaying tautomerism the primary isotope effects are found to have contributions from both intrinsic and equilibrium isotope effects. The primary tritium isotop...

S Bolvig, P E Hansen, H Morimoto, D Wemmer, P Williams (2000) MAGNETIC RESONANCE IN CHEMISTRY 38: 7 525-535

Application of the HECADE method to the measurement of long-range heteronuclear C-13,H-1 spin-spin coupling constants in tautomeric beta-sulfonylenamines

2011-02-13T13:38:21Z

Sequence-specific resonance assignments of the potent cytolysin equinatoxin II

2011-02-13T13:38:41Z

W Zhang, M G Hinds, G Anderluh, P E Hansen, R S Norton (2000) JOURNAL OF BIOMOLECULAR NMR 18: 3 281-282

Variable temperature H-1 and C-13 NMR spectroscopic investigation of the enol-enethiol tautomerism of beta-thioxoketones. Isotope effects due to deuteron chelation

2011-02-13T13:38:21Z

Sequence-specific resonance assignments of the potent cytolysin equinatoxin II

2011-02-13T13:38:21Z

W Zhang, M G Hinds, G Anderluh, P E Hansen, R S Norton (2000) JOURNAL OF BIOMOLECULAR NMR 18: 3 281-282

Stable ion study of regioisomeric carboxonium-substituted pyrenium ions : Directive effects, charge delocalization mode, and conformational aspects

2011-02-13T13:38:21Z

P-31 NMR for the study of P metabolism and translocation in arbuscular mycorrhizal fungi

2011-02-13T13:38:21Z

P-31 nuclear magnetic resonance (NMR) spectroscopy was used to study phosphate (P) metabolism in mycorrhizal and nonmycorrhizal roots of cucumber (Cucumis sativus L) and in external mycelium of the arbuscular mycorrhizal (AM) fungus Glomus intraradices Schenck & Smith. The in vivo NMR method allows biological systems to be studied non-invasively and non-destructively. (3)1P NMR experiments provide...

N Rasmussen, D C Lloyd, R G Ratcliffe, P E Hansen, I Jakobsen (2000) PLANT AND SOIL 226: 2 245-253

Primary tritium and deuterium isotope effects on chemical shifts of compounds having an intramolecular hydrogen bond

2011-02-13T13:38:21Z

Deuterium isotope effects on O-17 chemical shifts of intramolecularly hydrogen bonded systems

2011-02-13T13:39:04Z

Deuterium isotope effects on O-17 chemical shifts are studied in a series of intramolecularly hydrogen bonded o-hydroxy acyl aromatics and beta-diketones. Geometries and chemical shifts are calculated using DFT ab initio methods, Relationships between hydrogen bond strength represented as either R-O ... O, RO-H or R-O ... H, and the experimental parameters, (5)Delta(17)O(OD) and delta(17)O are dem...

S Bolvig, P E Hansen, D Wemmer, P Williams (1999) JOURNAL OF MOLECULAR STRUCTURE 509: 1-3 171-181

Deuterium isotope effects on C-13 chemical shifts of intramolecularly hydrogen-bonded Schiff bases

2011-02-13T13:39:04Z

The proton transfer equilibrium in a series of Schiff bases derived from substituted salicylic aldehydes and aliphatic amines has been investigated by means of variable temperature multinuclear magnetic resonance and the deuterium isotope effect on C-13 nuclear shielding. Most of the compounds exist in two tautomeric forms in CDCl3. The populations of the tautomeric forms have been estimated using...

Z Rozwadowski, E Majewski, T Dziembowska, P E Hansen (1999) JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 : 12 2809-2817

One-bond deuterium isotope effects on N-15 chemical shifts in Schiff bases

2011-02-13T13:39:26Z

A series of N-15 enriched Schiff bases have been investigated by means of N-15 NMR at variable temperature (300-200 K). Most realiable results are obtained below 250 K, as the exchange of the chelate proton is sufficiently slow on the NMR time scale at this temperature. The N-15 chemical shifts are found to vary linearly with the one bond N-15-H coupling constants. Deuterium isotope effects on N-1...

P E Hansen, J Sitkowski, L Stefaniak, Z Rozwadowski, T Dziembowska (1998) BERICHTE DER BUNSEN-GESELLSCHAFT-PHYSICAL CHEMISTRY CHEMICAL PHYSICS 102: 3 410-413

Conformational studies of phenyl- and (1-pyrenyl)triarylmethylcarbenium ions : Semiempirical calculations and NMR investigations under stable ion conditions

2011-02-13T13:39:26Z

Highly stable crowded carbenium ions such as (1-pyrenyl)diphenylmethylcarbenium ion (2) and 1,6-(3) and 1,8-bis(diphenylmethylenium)pyrene [dication] (4) and their dibrominated analogues (3Br and 4Br) have been studied at low and at ambient temperatures. 2 shows a conventional two-ring flip (ph,ph), whereas the disubstituted pyrene derivatives show one-ring flips (py) and two-ring flips (ph,ph) wi...

P E Hansen, J Spanget-Larsen, K K Laali (1998) JOURNAL OF ORGANIC CHEMISTRY 63: 6 1827-1835

C-13 NMR, X-ray, and differential scanning calorimetry investigations of truncated BPTI (aprotinin) analogues

2011-02-13T13:39:26Z

Truncated BPTI missing residues 1 and 2 is investigated together with variants thereof (Lys-15, Arg-17, and Arg-42 are replaced by other residues in various combinations). A comparison of the X-ray structure of BPTI with that of 3-58BPTI(K15R,R17A,R42S) shows only minor variations for the backbone, but the lack of salt bridge between the terminals and the lack of two N-terminal residues provide a ...

P E Hansen, W Zhang, C Lauritzen, S Bjorn, L C Petersen, K Norris, O H Olsen, C Betzel (1998) BIOCHEMISTRY 37: 11 3645-3653

Isotope effects on chemical shifts in tautomeric systems with double proton transfer. Citrinin

2011-02-13T13:39:26Z

Primary and secondary deuterium isotope effects on H-1 and C-13 chemical shifts are measured in citrinin, a tautomeric compound with an unusual doubly intramolecularly hydrogen bonded structure. The isotope effects are to a large extent dominated by equilibrium contributions and deuteration leads to more of the deuterated enol forms rather than the deuterated acid form. H-1, C-13 and O-17 nuclear ...

P E Hansen, M Langgard, S Bolvig (1998) POLISH JOURNAL OF CHEMISTRY 72: 2 269-276

Tautomerism of enolic triacetylmethane, 2-acyl-1,3-cycloalkanediones, 5-acyl Meldrum's acids and 5-acyl-1,3-dimethylbarbituric acids studied by means of deuterium isotope effects on C-13 chemical shifts

2011-02-13T13:39:26Z

Deuterium isotope effects on C-13 nuclear shielding, (n) Delta C(OD), were investigated for a series of enolic triacetylmethane, 2-acyl-1,3-cycloalkanediones, 5-acyl Meldrum's acids and 5-acyl-1,3-dimethylbarbituric acids at different temperatures. The enoloc 2-acyl-1,3-cycloalkanediones, 5-acyl Meldrum's acids and 5-acyl-1,3-dimethylbarbituric acids all exhibit intramolecular enol-enol tautomeris...

S Bolvig, F Duus, P E Hansen (1998) MAGNETIC RESONANCE IN CHEMISTRY 36: 5 315-324

Further insight via N-15 NMR spectroscopy into the reactive intermediates formed by superacid protonation of crowded nitro-PAHs : persistent dihydroxyiminiumpyrenium and hydroxyiminiumpyrenium dications

2011-02-13T13:39:04Z

Low temperature protonation of 1-nitropyrene and its N-15--labeled isotopomer with FSO3H . SbF5 (1:1) ('magic acid))-SO2ClF (or SO2) or with FSO3H . SbF5 (4:1)SO2ClF generates either the dihydroxyiminiumpyrenium dication (NO, diprotonation) or the hydroxyiminiumpyrenium dication as the principle NMR observable persistent species (depending on the sample concentration, reaction time and the superac...

K K Laali, P E Hansen (1998) JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 : 5 1167-1172

First examples of fluorinated and chlorinated polycyclic aromatic hydrocarbon (PAH) dications from benzo[a]pyrene, pyrene, and their alkyl-substituted derivatives

2011-02-13T13:39:04Z

Two-electron oxidations (SbF5/SO2ClF) of 6-fluoro-benzo[a]pyrene, 3, 6-chloro-benzo[a]pyrene 4, and their corresponding 7-methyl derivatives 5 and 6 as well as 1-fluoropyrene,;7, 1-chloropyrene, 8, and 1-fluoro-2,7-di-tert-butylpyrene, 9, allowed the charge delocalization mode, substituent effects, one-bond and long-range C/F coupling constants, and the tropicity of the resulting persistent PAH di...

K K Laali, M Tanaka, P E Hansen (1998) JOURNAL OF ORGANIC CHEMISTRY 63: 23 8217-8223

O-17 chemical shifts and deuterium isotope effects on C-13 chemical shifts of intramolecularly hydrogen-bonded compounds

2011-02-13T13:39:04Z

O-17 chemical shifts were measured in 40 enamines activated in the beta-position by C=O, COO, NO2, SO and SO2 groups. Data for the oxygen-containing series of o-hydroxyacyl aromatics are also included for comparison. Intramolecular hydrogen bonding in the enamines is discussed in terms of the acceptor and donor groups and the separating link. O-17 chemical shifts, the two-bond deuterium isotope sh...

L Kozerski, R Kawecki, P Krajewski, B Kwiecien, D W Boykin, S Bolvig, P E Hansen (1998) MAGNETIC RESONANCE IN CHEMISTRY 36: 12 921-928

(n)J(C-13,(OH)-H-1) coupling constants of intramolecularly hydrogen-bonded compounds

2011-02-13T13:39:04Z

(n)J(C-13,(OH)-H-1) carbon-hydrogen couplings were measured for a broad series of intramolecularly hydrogen-bonded compounds, some of which display tautomerism. A plot of J(obs)(C-3,OH) + J(obs)(C-1,OH) cs. delta OH showed reasonable correlation both for compounds displaying tautomerism and for those with localized hydrogen bonds. Ketones and aldehydes fall on one line and esters on another line c...

E V Borisov, W Zhang, S Bolvig, P E Hansen (1998) MAGNETIC RESONANCE IN CHEMISTRY 36: S104-S110

Unraveling the electronic and vibrational contributions to deuterium isotope effects on C-13 chemical shifts using ab initio model calculations. Analysis of the observed isotope effects on sterically perturbed intramolecular hydrogen-bonded o-hydroxy acyl aromatics

2011-02-13T13:39:04Z

Deuterium isotope effects on chemical shifts, (n)Delta C(OD),have been measured in a series,of o-hydroxy acyl aromatics of the type 2-hydroxyacetophenone (1) and 1,3,5-triacetyl-2,4,6-trihydroxybenzene (3). (2)Delta C(OD) increase as the number of neighboring hydrogen-bonded moieties increase. The calculated molecular ab initio geometries with Density Functional Theory(BPW91/6-31 G(d(p)) (5D) with...

J Abildgaard, S Bolvig, P E Hansen (1998) JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 120: 35 9063-9069

Stable ion studies of the chrysene skeleton. Protonation of chrysene, 6-halochrysenes, 6-acetylchrysene, and 4H-cyclopenta[def]chrysene : NMR studies of charge distribution in chrysenium cations and AM1 calculations

2011-02-13T13:39:50Z

Chrysene (1), 6-fluorochrysene (2), 6-chlorochrysene (3), and 6-bromochrysene (4) are cleanly monoprotonated in FSO3H . SbF5 (ca. 10:1)/SO2ClF at the C-12 position. 6-Acetylchrysene (5) is CO-protonated in FSO3H/SO2ClF with significant charge delocalization into the chrysene and provides a model for a C-6-protonated chrysenium cation. 4H-Cyclopenta[def]chrysene (6) is protonated at C-5 (site of br...

K K Laali, S Hollenstein, R G Harvey, P E Hansen (1997) JOURNAL OF ORGANIC CHEMISTRY 62: 12 4023-4028

Sorption of polycyclic aromatic compounds to humic acid as studied by high-performance liquid chromatography

2011-02-13T13:39:50Z

Aldrich humic acid was chemically immobilized to the silanol surface of a column material to be used for highperformance liquid chromatography (HPLC). The retention factors to the humic acid column material of 45 polycyclic aromatics compounds (PAC) were determined by HPLC. The PAC include PAH, N-, S-, O-PAC and substituted PAC (9-substituted anthracenes, bromopyrenes, and quinoline derivatives). ...

T Nielsen, K Siigur, C Helweg, O Jorgensen, P E Hansen, U Kirso (1997) ENVIRONMENTAL SCIENCE & TECHNOLOGY 31: 4 1102-1108

Deuterium isotope effects on C-13 chemical shifts of o-hydroxyacyl aromatics. Intramolecular hydrogen bonding

2011-02-13T13:39:50Z

The interesting deuterium isotope effects of gossypols have been reinvestigated and the very large two-bond isotope effect, (2) Delta C-6(OD), is ascribed to electric field effects. Common to the investigated compounds is the presence of intramolecular hydrogen bonds. A feature strongly related to the strength of the intramolecular hydrogen bond is intermolecular OH exchange. Electron-attracting s...

P E Hansen, S Bolvig (1997) MAGNETIC RESONANCE IN CHEMISTRY 35: 8 520-528

Determination of octanol-water partition coefficients of polar polycyclic aromatic compounds (N-PAC) by high performance liquid chromatography

2011-02-13T13:39:50Z

Prediction of 1-octanol water partition coefficients for a range of polar N-PAC from HPLC capacity coefficients has been investigated. Two commercially available columns, an ODS column and a Diol column were tested with water-methanol eluents. The best prediction of log K-ow for N-PAC was achieved using a Diol column with an eluent of 35 % MeOH and 65 % water. The results indicate that the Diol co...

C Helweg, T Nielsen, P E Hansen (1997) CHEMOSPHERE 34: 8 1673-1684

Deuterium isotope effects on C-13 chemical shifts of enaminones

2011-02-13T13:39:26Z

Deuterium isotope effects on C-13 chemical shifts have been studied in a series of substituted N-alkyl and N-phenyl keto-enamines. The intramolecularly hydrogen bonded Z-forms show the largest two-bond isotope effects, (2) Delta C-1(ND). Methyl-substitution al C-l leads to a larger two-bond isotope effect in the N-phenyl-substituted derivatives. This effect is ascribed to steric compression. Space...

D K Zheglova, D G Genov, S Bolvig, P E Hansen (1997) ACTA CHEMICA SCANDINAVICA 51: 10 1016-1023

Probing the charge delocalization mode in methyl-, dimethyl- and methylene-bridged phenanthrenium ions. NMR studies of persistent mono-and di-cations and AM1 calculations

2011-02-13T13:39:26Z

Superacid protonation studies are reported on 2-methyl-(1), 3-methyl-(2), 3,6-dimethyl-phenanthrene (3) and 4H-cyclopenta[def]phenanthrene (4). In FSO3H-SO2CIF persistent monocations 1H(+)-4H(+) are generated, 3 gives a symmetrical dication by protonation with FSO3H . SbF5(4:1)-SO2CIF or with 'magic acid'-SO2ClF. 1 and 2 are partially diprotonated in 'magic acid'-SO2ClF. The observed mono-and di-c...

K K Laali, S Hollenstein, P E Hansen (1997) JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 : 11 2207-2213

Long-range intrinsic and equilibrium deuterium isotope effects on F-19 chemical shifts

2011-02-13T13:39:26Z

Deuterium isotope effects on F-19 chemical shifts caused by deuteriation at OH or NH groups have been determined for intramolecularly hydrogen bonded compounds including fluorinated o-hydroxyacyl aromatics, enaminones, o-hydroxyazo and hydrate compounds. The o-hydroxyazo and hydrate compounds represent tautomeric and non-tautomeric cases. Deuterium isotope effects on fluorine chemical shifts for o...

P E Hansen, S Bolvig, A BuvariBarcza, A Lycka (1997) ACTA CHEMICA SCANDINAVICA 51: 8 881-888

Charge delocalization pathways in persistent 1-pyrenyl-, 4-pyrenyl-, and 2-pyrenylmethylcarbenium ions as models of PAH-epoxide ring opening : NMR studies in superacids and AM1 calculations

2011-02-13T13:39:26Z

The relative stability, magnitude, and mode of charge delocalization into the pyrene moiety (Py) were evaluated for a series of tertiary and secondary 1-pyrenylmethylcarbenium ions PyC+R1R2 and PyC+R3H (with R-1 = R-2 = Me and Ph; R-3 = Me, Ph, CH2Ph, and (CH2)(10)Me), 4-pyrenylmethylcarbenium ions (with R-1 = R-2 = Me; R-3 = Me and Ph), and 2-pyrenylmethylcarbenium ions (with R-1 = R-2 = Me). The...

K K Laali, P E Hansen (1997) JOURNAL OF ORGANIC CHEMISTRY 62: 17 5804-5810

Intramolecular hydrogen bonding in 8-quinolinol N-oxides, quinaldinic acid N-oxides and quinoline-2-carboxyamide N-oxide, deuterium isotope effects on C-13 chemical shifts

2011-02-13T13:39:26Z

Secondary isotope effects on C-13 chemical shifts have been measured in a series quinolinols, quinaldinic acid N-oxides and quinoline-2-carboxyamide N-oxide. For 8-quinolinol N-oxides a good correlation was found between delta OH and (n) Delta C(OD) isotope effects, The OH and C-13 chemical shifts and (n) Delta C(OD) show very small temperature dependences. The primary isotope effects are small, p...

T Dziembowska, Z Rozwadowski, P E Hansen (1997) JOURNAL OF MOLECULAR STRUCTURE 437: 189-199

Mono- and diprotonation of dihydropyrene, 2,7-di-tert-butyl-dihydropyrene, and their conversion to pyrenium ions; Influence of the radical cation and its potential utility in NMR assignments of the arenium ions of readily oxidizable PAHA

2011-02-13T13:39:50Z

Parent dihydropyrene 1 and 2,7-di-tert-butyldihydropyrene 3 are monoprotonated with FSO3H/SO2ClF to give their persistent monoarenium ions 1H(+) and 3H(+) by the attack of proton at C-3 (peri to the ethano-bridge not at C-l as previously suggested). Dihydropyrene 3 is diprotonated in FSO3H.SbF5 1:1 ''Magic Acid''(R)/SO2ClF to give the symmetrical dication H-3(2)+2, similar diprotonation of 1 with ...

K K Laali, P E Hansen (1996) RESEARCH ON CHEMICAL INTERMEDIATES 22: 8 737-751

Isotope effects as tools in basic and environmental research - Proceedings of the summer school held in Roskilde, Denmark, 24-28 June 1995 - Preface

2011-02-13T13:39:50Z

P E Hansen, A J Barnes (1996) JOURNAL OF MOLECULAR STRUCTURE 378: 1 R9-R9

Isotope Effects on Chemical Shifts as a Tool in Structural Studies.

2011-02-14T08:44:06Z

P. E. Hansen, (1996) :

Intramolecular hydrogen bonding of the enol forms of beta-ketoamides and beta-ketothioamides. Deuterium isotope effects on C-13 chemical shifts

2011-02-13T13:40:14Z

Deuterium isotope effects of C-13 chemical shifts are studied in a series of enol and keto forms of beta-ketoamides and the corresponding thioamides. In addition, the 2,6-cyclohexanediketo-1-amides and thioamides are studied. The effects of ring size (five- and six-membered rings) on the isotope effects and the tautomeric nature of the systems are also looked into. Rather unusual isotope effects a...

P E Hansen, F Duus, S Bolvig, T S Jagodzinski (1996) JOURNAL OF MOLECULAR STRUCTURE 378: 1 45-59

Complete assignment of H-1 and C-13 NMR spectra and conformational analysis of thioamide cannabinoids

2011-02-13T13:39:50Z

The complete assignment of the H-1 and C-13 NMR spectra of two carbothioamide- substituted meroterpenes is presented, Resonance assignments were achieved by the use of one- and two-dimensional MMR, NOED, selective decoupling measurements and the deuterium isotope effect on the C-13 chemical shifts. Six-membered ring conformations were determined by analysis of proton spin coupling constants with t...

J G Sosnicki, T S Jagodzinski, B NowakWydra, P E Hansen (1996) MAGNETIC RESONANCE IN CHEMISTRY 34: 9 667-674

Polycyclic aromatic hydrocarbon solute probes .12. Dissimilar fluorescence excitation/emission behavior between alkylpyrene and alkylcoronene derivatives and the parent pah molecule

2011-02-13T13:39:50Z

Fluorescence excitation and emission behavior are reported for methylcoronene, 1,2-dimethylcoronene, 2-isopropylpyrene, 4-isopropylpyrene, 2,4,7,1O-tetraisopropylpyrene, 1,3,6,8-tetraisopropylpyrene, 1,3,5,7,9-pentaisopropylpyrene, 2,7-di-tert-butylpyrene, 2,7-di-(dimethylpropyl)pyrene, 1,3,6,8-tetracyclopentylpyrene and 1,3,6,8-tetracyclohexylpyrene dissolved in various organic solvents of varyin...

J R Powell, S Pandey, B J Miller, W E Acree, P E Hansen, J C Fetzer (1996) JOURNAL OF LUMINESCENCE 69: 1 27-34

Deuterium-induced isotope effects on C-13 chemical shifts as a probe for tautomerism in enolic beta-diketones

2011-02-13T13:39:50Z

Deuterium isotope effects on C-13 nuclear shielding, ''Delta C(OD), were investigated for a series of enolic beta-diketones at different temperatures, The investigated enolic beta-diketones cover a broad range of tautomeric equilibrium constants (K). The equilibrium constants were estimated from O-17 and C-13 chemical shifts, C-13 chemical shifts and the deuterium isotope effects show changes with...

S Bolvig, P E Hansen (1996) MAGNETIC RESONANCE IN CHEMISTRY 34: 6 467-478

MONO-NITROALKYL-(CYCLOALKYL-)PYRENES AND DI-NITROALKYL-(CYCLOALKYL-)PYRENES IN SUPERACID MEDIA - DIHYDROXYIMINIUM-(OXOIMINIUM-)PYRENIUM DICATIONS - CYCLIZATION TO LONG-LIVED OXAZOLINE-PYRENIUM (AND 1,2-OXAZINE) PYRENIUM IONS - RING OPENING TO FORM NITROSOALKYLPYRENIUM AND NITROSO RADICAL-CATION SALTS WITH UNPRECEDENTED STABILITY

2011-02-13T13:40:14Z

The low temperature protonations of sterically crowded molecules 2,4,6,8,10-pentaisopropyl-1-nitropyrene 1, 2,4,6,8,10-pentaisopropyl-1,3-dinitropyrene 12, 3,6,8,10-tetracyclohexyl-1-nitropyrene 16, 2,7-di-tert-butyl-1-nitropyrene 19, 2,7-di-tert-butyl-1,8-dinitropyrene 21, 1,3,6,8-tetraisopropyl-4-nitropyrene 23 and parent 1-nitropyrene 28, all possessing buttressed nitro groups, were studied in ...

KK LAALI, S BOLVIG, PE HANSEN (1995) JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 : 3 537-551

Determination of Structural Changes in BPTI Mutants using 13C NMR Chemical Shifts.

2011-02-14T08:39:43Z

P. E. Hansen, C. Lauritzen, S. Bjørn, L. C. Petersen, K. Norris and O. H. Olsen, (1995) J.Cellul. Biochem., 21B: 72

DETERMINATION OF STRUCTURAL-CHANGES IN BPTI MUTANTS USING 13C NMR CHEMICAL-SHIFTS

2011-02-13T13:40:14Z

PE HANSEN, C LAURITZEN, LC PETERSEN, S BJORN, K NORRIS, OH OLSEN (1995) JOURNAL OF CELLULAR BIOCHEMISTRY : 72-72

Isotope Effects on 13C and 15N Chemical Shifts in Proteins from Electric Field Effects.

2011-02-14T08:40:41Z

J. Abildgaard, P. E. Hansen and Aa. E. Hansen, (1995) J.Cellul. Biochem., 21B: 68

SEARCHING CONFORMATIONAL SPACE IN FLEXIBLE MOLECULES USING NOES AND MOLECULAR MODELING

2011-02-13T13:40:14Z

A routine method for searching the conformational space of small flexible chain molecules in solution is presented. This involves the quantitative use of NOEs aided by molecular modeling. The l diastereomer of model compound (+/-)-N-(1-phenylethyl)-2-(ethylsulfinyl)-1-propenylamine (1) was studied in CDCl3 and pyridine-d(5) solutions using H-1 NMR. It was shown to undergo self-association in CDCl3...

L KOZERSKI, R KAWECKI, P KRAJEWSKI, P GLUZINSKI, K PUPEK, PE HANSEN, MP WILLIAMSON (1995) JOURNAL OF ORGANIC CHEMISTRY 60: 11 3533-3538

INTRAMOLECULAR HYDROGEN-BONDING AND TAUTOMERISM OF ACYLPYRAN-2,4-DIONES, ACYLPYRAN-2,4,6-TRIONES AND ACYLPYRIDINEDIONES AND BENZANNELATED DERIVATIVES - DEUTERIUM-ISOTOPE EFFECTS ON C-13 NMR CHEMICAL-SHIFTS

2011-02-13T13:40:14Z

The structures of acylpyran-diones, -triones and acylpyridinediones have been studied primarily by deuterium isotope effects on C-13 chemical shifts. The 3,5-diacetyltetrahydropyran-2,4,6-trione forms a double tautomeric system involving one of the carbonyl carbons of the anhydride moiety. This compound also exists as a minor symmetrical isomer with two intramolecular hydrogen bonds to the same ac...

PE HANSEN, S BOLVIG, T KAPPE (1995) JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 : 10 1901-1907

PROTONATION OF BENZO[A]PYRENE, DIBENZO[A,E]PYRENE AND BENZO[E] PYRENE IN SUPERACIDS - NMR-STUDIES OF CHARGE-DISTRIBUTION IN PERSISTENT ARENIUM IONS AND AM1 CALCULATIONS

2011-02-13T13:40:14Z

Benzo[a]pyrene 1 and dibenzo[a,e]pyrene 2 are monoprotonated with FSO3H-SO2ClF to give persistent arenium ions of protonation at C-6 (1H(+)) and C-8 (2H(+)), respectively. The low temperature protonation of benzo[e]pyrene 3 under a variety of conditions produced a mixture of arenium ions of attack at C-1 (3aH(+)) and C-3 (3bH(+)). The charge distribution pattern in the resulting arenium ions (as p...

KK LAALI, PE HANSEN, JJ HOUSER, M ZANDER (1995) JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 : 9 1781-1790

DEUTERIUM-ISOTOPE EFFECTS ON C-13 CHEMICAL-SHIFTS OF INTRAMOLECULARLY HYDROGEN-BONDED OLEFINS

2011-02-13T13:40:14Z

A series of intramolecularly hydrogen-bonded enamines, enols and enethiols with ester carbonylic, ketonic carbonylic, thioester carbonylic, nitro and sulphoxide accepters were investigated to obtain C-13 chemical shifts and deuterium isotope effects. Results from 33 new compounds and six remeasurements are compared with already existing data. An important aim was to show that isotope effects on ch...

PE HANSEN, S BOLVIG, F DUUS, MV PETROVA, R KAWECKI, R KRAJEWSKI, L KOZERSKI (1995) MAGNETIC RESONANCE IN CHEMISTRY 33: 8 621-631

ISOTOPE EFFECTS ON C-13 AND N-15 CHEMICAL-SHIFTS IN PROTEINS FROM ELECTRIC-FIELD EFFECTS

2011-02-13T13:40:14Z

J ABILDGAARD, PE HANSEN, AE HANSEN (1995) JOURNAL OF CELLULAR BIOCHEMISTRY : 68-68

HYDROGEN-BONDING AND TAUTOMERISM STUDIED BY ISOTOPE EFFECTS ON CHEMICAL-SHIFTS

2011-02-13T13:40:33Z

Deuterium isotope effects on C-13 chemical shifts are investigated in intramolecular hydrogen-bonded systems. As models, o-hydroxydibenzoylmethane and tetracycline (TC) are chosen. The OH proton is exchanged and the deuterium isotope effects at carbons, (n)DELTAC(OD), are studied in both localised and tautomeric situations. Factors influencing the isotope effects are the nature of donors, acceptor...

PE HANSEN (1994) JOURNAL OF MOLECULAR STRUCTURE 321: 1-2 79-87

AB-INITIO CALCULATIONS OF EXTERNAL CHARGE EFFECTS ON THE ISOTROPIC C-13, N-15 AND O-17 NUCLEAR SHIELDINGS OF AMIDES

2011-02-13T13:40:33Z

C-13=O, (CH3)-C-13, N-15 and O-17 isotropic NMR shieldings of model amides, acetamide and N-methylacetamide, in the presence of point charges and of hydrogen fluoride simulating dipolar perturbations, have been calculated by the ab initio LORG method. Positive and negative charges produce similar but opposite changes. The calculated effects are exaggerated compared to experiment, but the trends ar...

PE HANSEN, J ABILDGAARD, AE HANSEN (1994) CHEMICAL PHYSICS LETTERS 224: 3-4 275-282

DATA FOR THE CHARACTERIZATION OF THE GEOMETRICAL-ISOMERS OF BETA-SULPHINYLENAMINES

2011-02-13T13:40:33Z

NOE experiments at low temperature were used to establish the structure of the E- and Z-isomers of the enamine (BUSOCH)-S-t=CHNHBUt. The NOE experiments revealed large intermolecular NOE effects between E- and Z- isomers indicating the formation of dimers of specific orientation. NH chemical shifts and their temperature dependence showed that the E- and Z- isomers behave differently. The NH chemic...

L KOZERSKI, R KAWECKI, PE HANSEN (1994) MAGNETIC RESONANCE IN CHEMISTRY 32: 9 517-524

DEUTERIUM AND O-18 ISOTOPE EFFECTS ON C-13 CHEMICAL-SHIFTS OF STERICALLY HINDERED AND/OR INTRAMOLECULARLY HYDROGEN-BONDED O-HYDROXY ACYL AROMATICS

2011-02-13T13:40:33Z

A series of sterically hindered o-hydroxy aromatic ketones were synthesized, including benzene, naphthalene, phenanthrene and pyrene derivatives. Deuterium isotope effects on the C-13 chemical shifts of 2-hydroxy-1-acenaphthone and other sterically hindered, intramolecularly hydrogen-bonded aromatic ketones (OH exchanged) are shown to be unusual. The two-bond isotope effects are very large. Likewi...

PE HANSEN, SN IBSEN, T KRISTENSEN, S BOLVIG (1994) MAGNETIC RESONANCE IN CHEMISTRY 32: 7 399-408

C-13, H-1 AND 2-DIMENSIONAL NMR-STUDIES OF CHARGE-DISTRIBUTION IN STERICALLY CONGESTED PERSISTENT CYCLOALKYL-PYRENIUM AND ALKYL-PYRENIUM IONS GENERATED BY PROTONATION IN SUPERACID MEDIA

2011-02-13T13:40:33Z

In FSO3H-SO2ClF at low temperature, the symmetrical all alpha-substituted tetraisopropylpyrene 1, tetracyclohexylpyrene 2, and tetracyclopentylpyrene 3 monoprotonate at the ipso position to give 1H(+), 2H(+) and 3H(+), respectively. Whereas 1H(+) is directly observable by low-temperature NMR spectroscopy before it rearranges to 1aH(+), the sterically more congested pyrenium ions 2H(+) and 3H(+) ar...

KK LAALI, PE HANSEN (1994) JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 : 10 2249-2258

GENE TECHNOLOGY-BASED ANTIMETABOLITE DESIGN - THE USE OF AN IN-VITRO PROTEIN EXPRESSION SYSTEM TO FACILITATE ANTIMETABOLITE DESIGN FOR VIRALLY-INDUCED HUMAN-DISEASES AND MALIGNANT CONDITIONS

2011-02-13T13:40:14Z

A precondition for the chemotherapeutic treatment of a variety of virally-induced human diseases and malignant conditions is a highly selective interaction of the drug molecule to be used with it's biological target. To ensure the development of novel, effective drugs, it is essential that the biological target is well characterised with regard to it's structure and activity. Such characterisati...

YA BARNETT, K EGER, S ERIKSSON, G FOLKERS, PE HANSEN, R HOFBAUER, D KOMITOWSKY, A MILON, B MUNCHPETERSEN (1994) BIOTECHNOLOGY ADVANCES 12: 4 663-668

ASSIGNMENT OF THE LIGATING NITROGEN IN O,O'-DIHYDROXYAZOARENE COMPLEXES OF NICKEL(II), PALLADIUM(II), AND PLATINUM(II) BY H-1 AND C-13 NMR-SPECTROSCOPY

2011-02-13T13:40:14Z

The H-1 and C-13 NMR spectra of the soluble square-planar o,o'-dihydroxyazoarene-platinum(II) complexes [Pt-(L) (tba)] (L = 5,5'-dichloro-2,2'-dihydroxyazobenzenate (dhab), (5-chloro-2-hydroxyphenylazo)-3-oxo-N-phenylbutanamidate (hpab), or (5-chloro-2-hydroxyphenylazo)-2-naphtholate (hpan) and tba = tributylamine) and the protonated ligands have been assigned by use of homo- and heteronuclear 2D ...

J ABILDGAARD, PE HANSEN, J JOSEPHSEN, A LYCKA (1994) INORGANIC CHEMISTRY 33: 23 5271-5277

LONG-RANGE DEUTERIUM-ISOTOPE EFFECTS ON C-13 CHEMICAL-SHIFTS OF INTRAMOLECULARLY HYDROGEN-BONDED COMPOUNDS - PURPUROGALLINS

2011-02-13T13:40:57Z

Long-range deuterium isotope effects on C-13 chemical shifts, (n)DELTAC(OD), were studied in the intramolecularly hydrogen-bonded purpurogallins (benzotropolones). A very large long-range isotope effect from the hydrogen-bonded 4-OH(D) is observed over six bonds at C-7. Further, long-range isotope effects are transmitted over as many as eight bonds. The transmission pathway including the carbonyl ...

PE HANSEN (1993) MAGNETIC RESONANCE IN CHEMISTRY 31: 1 71-74

SUBSTITUENT EFFECTS ON DEUTERIUM-ISOTOPE EFFECTS ON NUCLEAR SHIELDING OF INTRAMOLECULARLY HYDROGEN-BONDED AROMATIC KETONES, ALDEHYDES AND ESTERS

2011-02-13T13:40:57Z

Deuterium isotope effects on C-13 nuclear shielding, (n)DELTAC(OD), were investigated for a large number of substituted ortho-substituted aromatic hydroxyacyl compounds of the type salicylaldehyde, 2-hydroxyacetophenone, etc. The isotope effects were analysed as a function of substitution patterns. 2DELTAC-2(OD) shows a linear dependence on deltaOH, with one slope for 4- and 6-substituted derivati...

PE HANSEN (1993) MAGNETIC RESONANCE IN CHEMISTRY 31: 1 23-37

CAN FLUORINE PERTURB THE SITE(S) OF ELECTROPHILIC ATTACK IN PYRENE - PERSISTENT FLUOROPYRENIUM IONS - GENERATION AND CHARGE-DISTRIBUTION PROBED BY MULTINUCLEAR NMR

2011-02-13T13:40:33Z

KK LAALI, PE HANSEN (1993) ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 205: 7-ORGN

VARIABLE-TEMPERATURE NMR-STUDIES OF 2,6-DIHYDROXY ACYLAROMATIC COMPOUNDS - DEUTERIUM-ISOTOPE EFFECTS ON CHEMICAL-SHIFTS, ISOTOPIC PERTURBATION OF EQUILIBRIUM AND BARRIERS TO ROTATION

2011-02-13T13:40:33Z

A series of 2,6-dihydroxy acylaromatic compounds were investigated to characterize the rotational and hydrogen bonding properties of the carbonyl group. Deuterium isotope effects on H-1 and C-13 chemical shifts due to deuteriation of OH groups were determined at both ambient and low temperature. In the latter case isotope effects on chemical shifts of the individual rotamers can be determined. Deu...

PE HANSEN, M CHRISTOFFERSEN, S BOLVIG (1993) MAGNETIC RESONANCE IN CHEMISTRY 31: 10 893-902

OXIDATION OF STERICALLY CROWDED ALKYL(CYCLOALKYL)PYRENES - PERSISTENT DICATIONS IN SBF5/SO2CLF AND RADICAL CATIONS IN FSO3H/SO2

2011-02-13T13:40:33Z

Sterically crowded alkylpyrenes 2-7 undergo two-electron oxidation with SbF5/SO2ClF (or SbF5.FSO3H (9:1)/SO2ClF) to give persistent alkylpyrene dications. In agreement with the charge distribution pattern observed in the parent pyrene dication and with semiempirical calculations (AM1) on isomeric monoisopropylpyrenes dications; the deshielding order C(alpha) > C(alphabeta) > C(beta) was found in t...

KK LAALI, PE HANSEN, E GELERINTER, JJ HOUSER (1993) JOURNAL OF ORGANIC CHEMISTRY 58: 15 4088-4095

GENERATION AND NMR-STUDIES OF PERSISTENT FLUORO(ALKYL)PYRENIUM IONS AND THEIR TETRAHYDRO AND HEXAHYDRO DERIVATIVES IN SUPERACID MEDIA

2011-02-13T13:40:33Z

Low-temperature protonations of 2-fluoropyrene (9), 2-fluoro-7-tert-butylpyrene (10), their corresponding tetrahydro analogs 11 and 12, 1-fluoropyrene (4), 4-fluoropyrene (15), and its derivative 14 are studied in various superacid media. The isomeric fluoro(alkyl)pyrenes are fully monoprotonated in FSO3H/SO2ClF and their tetrahydro and hexahydro analogs 11, 12, and 14 are monoprotonated with FSO3...

KK LAALI, PE HANSEN (1993) JOURNAL OF ORGANIC CHEMISTRY 58: 15 4096-4104

DELTA(2)H(D) AND DELTA(1)N(D) ISOTOPE EFFECTS ON NUCLEAR SHIELDING OF AMMONIUM-IONS IN COMPLEXES WITH CROWN-ETHERS AND CRYPTANDS

2011-02-13T13:40:33Z

One-bond deuterium isotope effects on nitrogen nuclear shielding, 1DELTAN(D) and two-bond isotope effects at H-1 nuclear shielding, 2DELTAH(D), have been investigated in a series of inclusion complexes. The hosts comprise, SC-24, [2.2.2], [2.2.1], [2.2.1]D, [2.2] DD, K5, 18-crown-6 and 18-crown-6 tetracarboxylic acid. The structure of the host [2.2.1 ] is discussed based on isotope effects and H-1...

PE HANSEN, AE HANSEN, A LYCKA, A BUVARIBARCZA (1993) ACTA CHEMICA SCANDINAVICA 47: 8 777-788

Nuclear Magnetic Resonance (NMR) of Acids and Acid Derivatives.

2011-02-14T10:16:21Z

P. E. Hansen, (1992) The Chemistry of Acid Derivatives, Vol. 2, Suppl. B2 153-226

EFFECTS OF N-TERMINAL EXTENSION PEPTIDES ON THE STRUCTURE AND STABILITY OF BOVINE PANCREATIC TRYPSIN-INHIBITOR STUDIED BY H-1-NMR

2011-02-13T13:40:57Z

Four N-terminal extended species of the wild-type bovine pancreatic trypsin inhibitor (WT-BPTI), Arg-BPTI (1-BPTI), Met-Glu-Ala-Glu-BPTI (4-BPTI), Ser-Ile-Glu-Gly-Arg-BPTI (5-BPTI) and Gly-Ser-Ile-Glu-Gly-Arg-BPTI (6-BPTI) have been studied by H-1 n.m.r. The overall structure of the protein is largely unaffected by the addition of extension peptides. pH titration effects on the C-terminal Ala 58 H...

C LAURITZEN, O SKOVGAARD, PE HANSEN, E TUCHSEN (1992) INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES 14: 6 326-332

ABINITIO CALCULATIONS OF DEUTERIUM-ISOTOPE EFFECTS ON HYDROGEN AND NITROGEN NUCLEAR MAGNETIC SHIELDING IN THE HYDRATED AMMONIUM ION

2011-02-13T13:40:57Z

H-1 and N-14 nuclear shieldings of the ammonium ion and of its mono- and tetrahydrated species in directional as well as non-directional coordinations are calculated ab initio using the localized orbital/local origin (LORG) method; counterpoise calculations are included to test for basis set superposition effects. The variation of the H-1 and N-14 shieldings with N-H distance is essentially linear...

M MUNCH, AE HANSEN, PE HANSEN, TD BOUMAN (1992) ACTA CHEMICA SCANDINAVICA 46: 11 1065-1071

DEUTERIUM-ISOTOPE EFFECTS ON C-13 NUCLEAR SHIELDING OF AMINO AND ACETAMIDO COMPOUNDS - TAUTOMERISM AND INTRAMOLECULAR HYDROGEN-BONDING

2011-02-13T13:40:57Z

Deuterium isotope effects on C-13 nuclear shielding were investigated for a series of o-amino and acetamido azo compounds and for amino- and acetamido-9,10-anthra- and leucoanthraquinones. A variety of these compounds form intramolecular hydrogen bonds and are possibly tautomeric in nature. Deuterium isotope effects on C-13 chemical shifts were used to probe both the tautomerism and the nature of ...

PE HANSEN, A KOLONICNY, A LYCKA (1992) MAGNETIC RESONANCE IN CHEMISTRY 30: 8 786-795

NITRATION OF ISOPROPYLPYRENES - STRAINED MODELS FOR PROTONATION AND TRANSFER NITRATION IN THE CONDENSED PHASE

2011-02-13T13:40:57Z

Protic mono- and dinitration of 1,3,5,7,9-pentaisopropylpyrene (1) occurred at the available alpha positions to give 2 and 3. Despite steric crowding, 2 and 3 did not exhibit a torsional barrier to i-Pr rotation at ambient temperatures; however, buttressing of the peri i-Pr groups was evident (H-1 NMR, UV, and force field energy minimizations). Persistent (dihydroxyiminium)pyrenium dications 2a+2...

KK LAALI, TM LIANG, PE HANSEN (1992) JOURNAL OF ORGANIC CHEMISTRY 57: 9 2658-2667

HYDROGEN-BONDING MONITORED BY DEUTERIUM-ISOTOPE EFFECTS ON CARBONYL C-13 CHEMICAL-SHIFT IN BPTI - INTRA-RESIDUE HYDROGEN-BONDS IN ANTIPARALLEL BETA-SHEET

2011-02-13T13:41:42Z

Deuterium isotope effects on carbonyl C-13 magnetic shielding were measured for the backbone carbonyl groups in BPTI (basic pancreatic trypsin inhibitor), and interpreted as a measure of hydrogen bond energies. The effects originate from peptide amide proton deuterium substitution and were observed on carbonyl carbons separated by two or three covalent bonds from the amide H/D. Two-bond isotope ...

E TUCHSEN, PE HANSEN (1991) INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES 13: 1 2-8

AGGREGATION OF AMPHIPHILIC MOLECULES IN WATER .1. ALPHA-PHENYLETHYLAMINE - H-1 AND C-13 NMR-STUDY

2011-02-13T13:41:19Z

The concentration dependence of the H-1 and C-13 NMR chemical shifts in D2O and in CDCl3 solutions were determined for (+/-)-alpha-phenylethylamine (I). Aqueous solutions of (-)-I and (+)-I, 50% enantiomerically enriched in (-)-and (+/-)-2,2,2,-trifluoro-1-phenylethanol and the (+)-and (-)-N-formyl derivatives of I, were also studied. H-1 nuclear Overhauser enhancements were used to check the co...

L KOZERSKI, PE HANSEN (1991) JOURNAL OF PHYSICAL ORGANIC CHEMISTRY 4: 1 58-66

AGGREGATION OF AMPHIPHILIC MOLECULES IN WATER .1. ALPHA-PHENYLETHYLAMINE - H-1 AND C-13 NMR-STUDY

2011-02-13T13:41:42Z

LONG-RANGE DEUTERIUM-ISOTOPE EFFECTS IN TAUTOMERIC BETA-THIOXOKETONES - A H-1 AND C-13 NMR-STUDY

2011-02-13T13:40:57Z

Equilibrium displacements within the enol-enthiolic tautomeric systems of beta-thioxoketones caused by long-range isotope effects were monitored by H-1 and C-13 NMR spectroscopy. Thioacetylacetone and 1,3-diphenyl-3-thioxopropanone deuteriated at various positions were investigated. Both compounds are in fast (Z)-enol-(Z)-enethiol equilibrium on the NMR time scale. The investigations showed tha...

PE HANSEN, U SKIBSTED, F DUUS (1991) JOURNAL OF PHYSICAL ORGANIC CHEMISTRY 4: 4 225-232

N-Extension of BPTI. A Model for Folding and Long-range Interac¬tions.

2011-02-13T14:13:58Z

C. Lauritzen, O. Skovgaard, E. Tüchsen and P. E. Hansen, (1991) J. Cellul. Biochem., S156: 65

ASSIGNMENT OF THE NATURAL ABUNDANCE C-13 SPECTRUM OF PROTEINS USING C-13 H-1-DETECTED HETERONUCLEAR MULTIPLE-BOND CORRELATION NMR-SPECTROSCOPY - STRUCTURAL INFORMATION AND STEREOSPECIFIC ASSIGNMENTS FROM 2-BOND AND 3-BOND CARBON HYDROGEN COUPLING-CONSTANTS

2011-02-13T13:40:57Z

Proton-detected heteronuclear multiple-bond H-1-C-13 correlations (HMBC) previously have been used for assignment purposes in a variety of isotopically enriched proteins. In the present study it is demonstrated that the technique yields an almost complete assignment of the natural abundance C-13 Spectrum of the protein basic pancreatic trypsin inhibitor (BPTI). In addition, the technique permits a...

PE HANSEN (1991) BIOCHEMISTRY 30: 43 10457-10466

HYDROGEN-BONDING MONITORED BY DEUTERIUM-ISOTOPE EFFECTS ON CARBONYL C-13 CHEMICAL-SHIFT IN BPTI - INTRA-RESIDUE HYDROGEN-BONDS IN ANTIPARALLEL BETA-SHEET

2011-02-13T13:41:19Z

PROTONATION AND SULFINYLATION OF ISOMERIC ISOPROPYLPYRENES, 2,7-DI-TERT-BUTYLPYRENE, AND TETRACYCLOHEXYLPYRENES AND TETRACYCLOPENTYLPYRENES - REMARKABLY STABLE, STERICALLY CROWDED PYRENIUM CATIONS

2011-02-13T13:40:57Z

1-Isopropyl- (1), 2-isopropyl- (2), 4-isopropyl- (3), 1,3,6,8-tetraisopropyl- (4), and 1,3,5,7,9-pentaisopropylpyrene (5), 2,7-di-tert-butylpyrene (6), and 1,3,5,8-tetracyclohexyl- (7) and 2,4,7,9-tetracyclopentylpyrene (8) in FSO3H or CF3SO3H (TfOH) in SO2 or SO2ClF solvent gave stable monopyrenium ions. In agreement with theory, exclusive alpha protonation occurred at low temperature (-75 --> -...

KK LAALI, PE HANSEN (1991) JOURNAL OF ORGANIC CHEMISTRY 56: 24 6795-6803

DEUTERIUM-ISOTOPE EFFECTS ON C-13 AND N-15 NUCLEAR SHIELDING IN INTRAMOLECULARLY HYDROGEN-BONDED COMPOUNDS - INVESTIGATION OF ENAMINE DERIVATIVES

2011-02-13T13:41:19Z

PE HANSEN, R KAWECKI, A KROWCZYNSKI, L KOZERSKI (1990) ACTA CHEMICA SCANDINAVICA 44: 8 826-832

DEUTERIUM-ISOTOPE EFFECTS ON C-13 AND N-15 NUCLEAR SHIELDING IN INTRAMOLECULARLY HYDROGEN-BONDED COMPOUNDS - INVESTIGATION OF ENAMINE DERIVATIVES

2011-02-13T13:41:42Z

PE HANSEN, R KAWECKI, A KROWCZYNSKI, L KOZERSKI (1990) ACTA CHEMICA SCANDINAVICA 44: 8 826-832

13C Chemical Shi¬fts and Deute¬rium Isotope Effects for Structure Determina¬tion of Prot¬eins.

2011-02-13T14:12:23Z

P. E. Hansen and E. Tüchsen, (1989) J. Cellul. Biochem. 13A: 31

TWO-DIMENSIONAL H-1-NMR AND C-13-NMR SPECTRA OF SOME AZO DYES CONTAINING AMINO OR ACETAMIDO GROUPS

2011-02-13T13:41:42Z

A LYCKA, J JIRMAN, PE HANSEN (1989) DYES AND PIGMENTS 10: 4 259-268

DEUTERIUM-ISOTOPE EFFECTS ON CARBONYL CARBON CHEMICAL-SHIFTS OF BPTI - HYDROGEN-BONDING AND STRUCTURE DETERMINATION IN PROTEINS

2011-02-13T13:41:19Z

PE HANSEN, E TUCHSEN (1989) ACTA CHEMICA SCANDINAVICA 43: 7 710-712

DEUTERIUM-ISOTOPE EFFECTS ON CARBONYL CARBON CHEMICAL-SHIFTS OF BPTI - HYDROGEN-BONDING AND STRUCTURE DETERMINATION IN PROTEINS

2011-02-13T13:41:42Z

PE HANSEN, E TUCHSEN (1989) ACTA CHEMICA SCANDINAVICA 43: 7 710-712

NMR of C=C, C=O, C=N and N=N Double bonds

2011-02-14T10:21:18Z

P. E. Hansen, (1989) The Chemistry of Double bonded Functional Groups 81-162

TWO-DIMENSIONAL H-1-NMR AND C-13-NMR SPECTRA OF SOME AZO DYES CONTAINING AMINO OR ACETAMIDO GROUPS

2011-02-13T13:41:19Z

A LYCKA, J JIRMAN, PE HANSEN (1989) DYES AND PIGMENTS 10: 4 259-268

A REINVESTIGATION OF ONE-BOND DEUTERIUM-ISOTOPE EFFECTS ON NITROGEN AND ON PROTON NUCLEAR SHIELDING FOR THE AMMONIUM ION

2011-02-13T13:41:19Z

PE HANSEN, A LYCKA (1989) ACTA CHEMICA SCANDINAVICA 43: 3 222-232

A REINVESTIGATION OF ONE-BOND DEUTERIUM-ISOTOPE EFFECTS ON NITROGEN AND ON PROTON NUCLEAR SHIELDING FOR THE AMMONIUM ION

2011-02-13T13:41:42Z

PE HANSEN, A LYCKA (1989) ACTA CHEMICA SCANDINAVICA 43: 3 222-232

ISOTOPIC PERTURBATION OF EQUILIBRIUM IN 2,6-DIHYDROXYBENZOYL COMPOUNDS - A C-13 AND H-1-NMR INVESTIGATION

2011-02-13T13:41:42Z

PE HANSEN (1988) ACTA CHEMICA SCANDINAVICA SERIES B-ORGANIC CHEMISTRY AND BIOCHEMISTRY 42: 7 423-432

CARBONYL C-13 NMR-SPECTRUM OF BASIC PANCREATIC TRYPSIN-INHIBITOR - RESONANCE ASSIGNMENTS BY SELECTIVE AMIDE HYDROGEN ISOTOPE LABELING AND DETECTION OF ISOTOPE EFFECTS ON C-13 NUCLEAR SHIELDING

2011-02-13T13:41:19Z

E TUCHSEN, PE HANSEN (1988) BIOCHEMISTRY 27: 23 8568-8576

ISOTOPE EFFECTS IN NUCLEAR SHIELDING

2011-02-13T13:41:19Z

PE HANSEN (1988) PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 20: 207-255

ISOTOPIC PERTURBATION OF EQUILIBRIUM IN 2,6-DIHYDROXYBENZOYL COMPOUNDS - A C-13 AND H-1-NMR INVESTIGATION

2011-02-13T13:41:19Z

PE HANSEN (1988) ACTA CHEMICA SCANDINAVICA SERIES B-ORGANIC CHEMISTRY AND BIOCHEMISTRY 42: 7 423-432

CARBONYL C-13 NMR-SPECTRUM OF BASIC PANCREATIC TRYPSIN-INHIBITOR - RESONANCE ASSIGNMENTS BY SELECTIVE AMIDE HYDROGEN ISOTOPE LABELING AND DETECTION OF ISOTOPE EFFECTS ON C-13 NUCLEAR SHIELDING

2011-02-13T13:41:42Z

E TUCHSEN, PE HANSEN (1988) BIOCHEMISTRY 27: 23 8568-8576

ISOTOPE EFFECTS IN NUCLEAR SHIELDING

2011-02-13T13:41:42Z

PE HANSEN (1988) PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 20: 207-255

CARBON-CARBON [J-N(C=O, C)] AND CARBON-FLUORINE COUPLING-CONSTANTS [J-N(CF)] OF ORTHO-SUBSTITUTED BENZOIC-ACIDS AND ACID FLUORIDES - INDO-SOS CALCULATIONS AND EVALUATION OF ROTATIONAL EFFECTS

2011-02-13T13:41:42Z

PE HANSEN, A BERG, K SCHAUMBURG (1987) MAGNETIC RESONANCE IN CHEMISTRY 25: 6 508-513

CARBON-CARBON [J-N(C=O, C)] AND CARBON-FLUORINE COUPLING-CONSTANTS [J-N(CF)] OF ORTHO-SUBSTITUTED BENZOIC-ACIDS AND ACID FLUORIDES - INDO-SOS CALCULATIONS AND EVALUATION OF ROTATIONAL EFFECTS

2011-02-13T13:41:19Z

PE HANSEN, A BERG, K SCHAUMBURG (1987) MAGNETIC RESONANCE IN CHEMISTRY 25: 6 508-513

FORMATION OF SEC-ALKYLPYRENES BY FRIEDEL-CRAFTS AND CATHODIC ALKYLATION METHODS - STRUCTURE AND SPECTROSCOPIC PROPERTIES OF PRODUCTS - CATALYTIC-HYDROGENATION OF PYRENE AND SOME ALKYLPYRENES

2011-02-13T13:42:02Z

A BERG, J LAM, PE HANSEN (1986) ACTA CHEMICA SCANDINAVICA SERIES B-ORGANIC CHEMISTRY AND BIOCHEMISTRY 40: 8 665-677

DEUTERIUM-ISOTOPE EFFECTS ON THE C-13 NUCLEAR SHIELDING OF INTRAMOLECULARLY HYDROGEN-BONDED SYSTEMS

2011-02-13T13:42:02Z

PE HANSEN (1986) MAGNETIC RESONANCE IN CHEMISTRY 24: 10 903-910

CARBON CARBON COUPLING-CONSTANTS OF 1-PHENYLAZO-2-NAPHTHOL AND 2-PHENYLAZO-1-NAPHTHOL OBTAINED BY THE SEMINA-1 TECHNIQUE

2011-02-13T13:42:02Z

PE HANSEN, A LYCKA (1986) MAGNETIC RESONANCE IN CHEMISTRY 24: 9 772-776

DEUTERIUM-ISOTOPE EFFECTS ON NUCLEAR SHIELDING - DIRECTIONAL EFFECTS AND NONADDITIVITY IN ACYL DERIVATIVES

2011-02-13T13:42:02Z

PE HANSEN, FM NICOLAISEN, K SCHAUMBURG (1986) JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 108: 4 625-629

DEUTERIUM-ISOTOPE EFFECTS ON N-14 AND N-15 NUCLEAR SHIELDING IN SIMPLE NITROGEN-CONTAINING COMPOUNDS

2011-02-13T13:42:02Z

A LYCKA, PE HANSEN (1985) MAGNETIC RESONANCE IN CHEMISTRY 23: 11 973-976

SOLVENT-INDUCED DEUTERIUM-ISOTOPE EFFECTS ON F-19 CHEMICAL-SHIFTS OF SOME SUBSTITUTED FLUOROBENZENES - FORMATION OF INCLUSION COMPLEXES

2011-02-13T13:42:02Z

PE HANSEN, HD DETTMAN, BD SYKES (1985) JOURNAL OF MAGNETIC RESONANCE 62: 3 487-496

BETA-THIOXO ESTERS .5. DETERMINATION OF TAUTOMERIC PHENOTYPES OF BETA-THIOXO ESTERS AND CHARACTERIZATION OF THE TAUTOMERIC ENETHIOLIC CONSTITUENTS BY MEANS OF C-13 NMR-SPECTROSCOPY

2011-02-13T13:42:27Z

F DUUS, PE HANSEN (1984) ORGANIC MAGNETIC RESONANCE 22: 1 16-23

DEUTERIUM-ISOTOPE EFFECTS ON C-13 AND N-15 NUCLEAR SHIELDING IN ORTHO-HYDROXYAZO DYES

2011-02-13T13:42:02Z

A LYCKA, PE HANSEN (1984) ORGANIC MAGNETIC RESONANCE 22: 9 569-572

A NATURAL ABUNDANCE N-15 NMR INVESTIGATION OF BILIRUBIN-IX-ALPHA

2011-02-13T13:42:02Z

PE HANSEN, HJ JAKOBSEN (1984) ORGANIC MAGNETIC RESONANCE 22: 10 668-670

CARBON-PROTON COUPLING-CONSTANTS IN ALLENES, ETHENES AND BUTATRIENES - APPLICATION TO CONFORMATIONAL-ANALYSIS OF ALLENYL AND VINYL ALKYL ETHERS AND THIOETHERS

2011-02-13T13:42:02Z

NJ KOOLE, MJA DEBIE, PE HANSEN (1984) ORGANIC MAGNETIC RESONANCE 22: 3 146-163

2-FLUORO-ATP, A FLUORINATED ATP ANALOG - F-19 NUCLEAR MAGNETIC-RESONANCE STUDIES OF THE 2-FLUORO-ADP.MYOSIN SUBFRAGMENT-1 COMPLEX

2011-02-13T13:42:27Z

JH BALDO, PE HANSEN, JW SHRIVER, BD SYKES (1983) CANADIAN JOURNAL OF BIOCHEMISTRY AND CELL BIOLOGY 61: 2-3 115-119

THERMAL REARRANGEMENTS OF AROMATIC-COMPOUNDS .6. AUTOMERIZATION OF PYRENE A TEST FOR THE MECHANISM OF NAPHTHALENE AUTOMERIZATION

2011-02-13T13:42:27Z

LT SCOTT, MA KIRMS, A BERG, PE HANSEN (1982) TETRAHEDRON LETTERS 23: 18 1859-1862

DEUTERIUM-ISOTOPE EFFECTS ON C-13 NUCLEAR SHIELDING AS A MEASURE OF TAUTOMERIC EQUILIBRIA

2011-02-13T13:42:27Z

PE HANSEN, F DUUS, P SCHMITT (1982) ORGANIC MAGNETIC RESONANCE 18: 1 58-61

C-13,C-13 COUPLING-CONSTANTS FROM A MIXTURE OF ISOTOPOMERS (C-13) OF SUBSTITUTED AROMATIC-COMPOUNDS - 1-NITRONAPHTHALENES

2011-02-13T13:42:27Z

PE HANSEN, JP ALBRAND (1981) ORGANIC MAGNETIC RESONANCE 17: 1 66-67

ONE-BOND CARBON-CARBON SPIN-SPIN COUPLING-CONSTANTS - A DATA SUMMARY

2011-02-13T13:42:47Z

PE HANSEN, V WRAY (1981) ORGANIC MAGNETIC RESONANCE 15: 1 102-103

Spin-spin Carbon-carbon Coupling Constants.

2011-02-13T14:09:17Z

P. E. Hansen, (1981) Ann. Reports on NMR Spectroscopy 11A: 65-98

CARBON-HYDROGEN SPIN-SPIN COUPLING-CONSTANTS

2011-02-13T13:42:27Z

PE HANSEN (1981) PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 14: 175-296

CH, CD, CC AND HH COUPLING-CONSTANTS IN ISOTOPICALLY ENRICHED CYCLOBUTENE

2011-02-13T13:42:47Z

PE HANSEN, JJ LED (1981) ORGANIC MAGNETIC RESONANCE 15: 3 288-293

BILIRUBIN ACIDITY - TITRIMETRIC AND C-13 NMR-STUDIES

2011-02-13T13:42:47Z

PE HANSEN, H THIESSEN, R BRODERSEN (1979) ACTA CHEMICA SCANDINAVICA SERIES B-ORGANIC CHEMISTRY AND BIOCHEMISTRY 33: 4 281-293

C-13, C-13 COUPLING-CONSTANTS IN PHENYL SUBSTITUTED ETHYLENE, NAPHTHALENE, PHENANTHRENE AND CYCLOPENTADIENONE - DEPENDENCE ON DIHEDRAL ANGLES - DETERMINATION OF SIGNS BY THE SYMMETRICAL DOUBLE LABELING (SDL) METHOD .4.

2011-02-13T13:42:47Z

PE HANSEN, OK POULSEN, A BERG (1979) ORGANIC MAGNETIC RESONANCE 12: 1 43-49

SUBSTITUENT CONFORMATIONAL EFFECTS IN VICINAL C-13-C-13 SPIN-SPIN COUPLING-CONSTANTS

2011-02-13T13:42:47Z

JL MARSHALL, LG FAEHL, R KATTNER, PE HANSEN (1979) ORGANIC MAGNETIC RESONANCE 12: 3 169-173

C-13 NMR OF POLYCYCLIC AROMATIC-COMPOUNDS

2011-02-13T13:42:47Z

PE HANSEN (1979) ORGANIC MAGNETIC RESONANCE 12: 3 109-142

C-13, C-13 COUPLING-CONSTANTS IN ANTHRACENE, 9,10-DIHYDROANTHRACENE AND PHTHALIC-ACID DERIVATIVES - DETERMINATION OF SIGNS BY THE SYMMETRICAL DOUBLE LABELING (SDL) METHOD .5.

2011-02-13T13:43:12Z

PE HANSEN, A BERG (1979) ORGANIC MAGNETIC RESONANCE 12: 1 50-54

LONG-RANGE C-13-C-13 COUPLING-CONSTANTS - REVIEW

2011-02-13T13:43:12Z

PE HANSEN (1978) ORGANIC MAGNETIC RESONANCE 11: 5 215-232

DISSOLVING METAL AND ELECTROCHEMICAL REDUCTION OF POLYCYCLIC AROMATIC-HYDROCARBONS

2011-02-13T13:43:12Z

PE HANSEN, O BLAABJERG, A BERG (1978) ACTA CHEMICA SCANDINAVICA SERIES B-ORGANIC CHEMISTRY AND BIOCHEMISTRY 32: 10 720-726

NMR-STUDIES OF MYOSIN S-1 ATPASE

2011-02-13T13:43:12Z

JH BALDO, JW SHRIVER, PE HANSEN, BD SYKES (1978) BIOPHYSICAL JOURNAL 21: 3 A141-A141

C-13,C-13 COUPLING-CONSTANTS AND C-13 CHEMICAL-SHIFTS OF AROMATIC CARBONYL-COMPOUNDS - EFFECTS OF ORTHO-INTERACTIONS AND PERI-INTERACTIONS INVOLVING CARBONYL SUBSTITUENT

2011-02-13T13:43:12Z

PE HANSEN, OK POULSEN, A BERG (1977) ORGANIC MAGNETIC RESONANCE 9: 11 649-658

C-14 SHIELDING EFFECTS AT GAMMA-CARBON ATOMS IN SIDE-CHAINS OF ALPHA-AMINO-ACIDS

2011-02-13T13:43:12Z

PE HANSEN, JG BATCHELOR, J FEENEY (1977) JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 : 1 50-54

C-13-F-19 SPIN-SPIN COUPLING IN SOME MONOFLUORO-SUBSTITUTED POLYCYCLIC AROMATIC-HYDROCARBONS

2011-02-13T13:43:12Z

PE HANSEN, A BERG, HJ JAKOBSEN, AP MANZARA, J MICHL (1977) ORGANIC MAGNETIC RESONANCE 10: 179-187

C-13-C-13 COUPLING-CONSTANTS IN DERIVATIVES OF TRANS-STILBENE AND TETRAPHENYLETHYLENE - DETERMINATION OF RELATIVE SIGNS II

2011-02-13T13:43:12Z

PE HANSEN, OK POULSEN, A BERG (1976) ORGANIC MAGNETIC RESONANCE 8: 12 632-637

(C-C13)C-13 COUPLING-CONSTANTS IN DIMETHYL PHTHALATE AND PHTHALIC ANHYDRIDE - DETERMINATION OF SIGNS .3.

2011-02-13T13:43:40Z

PE HANSEN, A BERG (1976) ORGANIC MAGNETIC RESONANCE 8: 11 591-592

CATHODIC TERT-BUTYLATION OF PYRENE

2011-02-13T13:43:40Z

PE HANSEN, A BERG, H LUND (1976) ACTA CHEMICA SCANDINAVICA SERIES B-ORGANIC CHEMISTRY AND BIOCHEMISTRY 30: 3 267-270

DETERMINATION OF RELATIVE SIGNS OF C-13-C-13 COUPLING-CONSTANTS IN DOUBLY LABELED COMPOUNDS

2011-02-13T13:43:40Z

PE HANSEN, OK POULSEN, A BERG (1975) ORGANIC MAGNETIC RESONANCE 7: 8 405-406

C-13-C-13 COUPLING-CONSTANTS AND SUBSTITUENT EFFECTS ON C-13 CHEMICAL-SHIFTS IN C-13 LABELED PYRENE AND PYRENE DERIVATIVES

2011-02-13T13:43:40Z

PE HANSEN, OK POULSEN, A BERG (1975) ORGANIC MAGNETIC RESONANCE 7: 1 23-25

LONG-RANGE C-13-H-1 SPIN-SPIN COUPLING-CONSTANTS IN AMINO-ACIDS, CONFORMATIONAL APPLICATIONS

2011-02-13T13:43:40Z

PE HANSEN, J FEENEY, GCK ROBERTS (1975) JOURNAL OF MAGNETIC RESONANCE 17: 2 249-261

SUBSTITUENT EFFECTS ON C-13-C-13 COUPLING-CONSTANTS AND CHEMICAL-SHIFTS IN C-13 LABELED POLYCYCLIC AROMATIC HYDROXY COMPOUNDS

2011-02-13T13:43:40Z

PE HANSEN, OK POULSEN, A BERG (1975) ORGANIC MAGNETIC RESONANCE 7: 10 475-477

Use of C-13-H-1 Spin-coupling Constants in the Determination of Side-chain Conformations of Amino-acids

2011-02-13T13:43:40Z

It is shown that by considering the C-13-C-C-H coupling constant between the alpha-CO2- and the beta-protons in amino-acids it is possible to obtain side-chain conformational information concerning the rotamer populations which is not available from studies of H-H coupling constants alone.

J Feeney, P E Hansen, G C K Roberts (1974) JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS : 12 465-466

Sixteen 13C - 19F Spin-spin Coupling Constants in the 13C NMR Spectrum of 1-Flouropyrene.

2011-02-13T14:01:56Z

A. Berg, P. E. Hansen and H. J. Jakobsen, (1972) Acta Chem. Scand 26: 2159-2161

NMR Investigations on Pyrene.

2011-02-13T14:03:05Z

Poul Erik Hansen and Arne Berg, (1971) Acta Chem. Scand. 25: 3377-3387

2011-02-13T13:45:56Z

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