Hydrogen Bonds between Sexual Hormones and Nucleobases: NMR Investigations *§

1973 ◽  
Vol 28 (9-10) ◽  
pp. 494-498 ◽  
Author(s):  
Wolfgang Schimmack ◽  
Wolfgang Lohmann
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Hydrogen Bonds ◽  
Ethinyl Estradiol ◽  
Hydroxyl Group ◽  
Kcal Mole ◽  
Sexual Hormones ◽  
Nmr Parameters

Abstract The hydrogen-bonded complexes of 17 α-ethinyl-estradiol, progesterone, and testosterone with adenine- and uracil-derivatives have been investigated by means of nuclear magnetic resonance (NMR) spectroscopy using deutero-chloroform as a solvent. The thermodynamic and NMR-parameters (equilibrium constant K, enthalpy ΔH, entropy ΔS, and relative chemical shift of the complexes ΔδC) for selfassociation and mixed association have been determined. The strongest complex was formed by the phenolic hydroxyl group of estradiol with dimethyl-adenine (K = 14 mole- 1 , - ΔH = i kcal/mole, - ΔS = 8 cal/m ole-grad). The values were considerably less for the OH-17 group of estradiol and testosterone. The interaction of the keto groups of progesterone and testo sterone with nucleobases was very weak: K < 1 .0 mole- 1 . The biological importance of these results is discussed.

Nuclear magnetic resonance studies of microemulsions and related systems: 2-butoxyethanol in water

1984 ◽  
Vol 62 (1) ◽  
pp. 56-63 ◽  
Author(s):  
O. Desrosiers ◽  
T. Van Dinter ◽  
J. K. Saunders
Keyword(s):  
Phase Transition ◽  
Aqueous Solution ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Pure Liquid ◽  
Population Changes ◽  
Magnetic Resonance Studies ◽  
Nmr Parameters ◽  
Dilute Aqueous Solution

The 13C chemical shift, T1 and 2H T1 data for 2-butoxyethanol (BE) in D2O as a function of concentration are presented. The nmr parameters are consistent with thermodynamic data for the same system in that it appears that 2-butoxyethanol in water undergoes a pseudo phase transition at about 1.2 M. The chemical shift for each carbon is different in the microphase relative to either aqueous solution or pure BE. The shift differences are due to a combination of factors, conformer population changes, changes in the polarity of the oxygen, and a solvent effect on chemical shift. The more organic the medium, the higher the population of trans relative to gauche conformers. The motion of BE is more restricted in the microphase than in either dilute aqueous solution or in the pure liquid. The number of adsorbed D2O molecules per molecule of BE is less in the microphase than in aqueous solution.

The characterization of primary, secondary, and tertiary vanadate alkyl esters by 51V nuclear magnetic resonance spectroscopy

1988 ◽  
Vol 66 (10) ◽  
pp. 2570-2574 ◽  
Author(s):  
Alan S. Tracey ◽  
Michael J. Gresser
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Chemical Shifts ◽  
Hydroxyl Group ◽  
Resonance Spectroscopy ◽  
Low Field ◽  
Nuclear Magnetic

A variety of alkyl vanadates has been studied by 51V nuclear magnetic resonance spectroscopy. It was found that the equilibrium constant for condensation of vanadate with alcohols is insensitive to whether the hydroxyl group is primary, secondary, or tertiary. These products, however, have characteristic vanadium chemical shifts that allow assignment of nmr signals to the appropriate ester. It was also found that chemical shifts are additive in the sense that the chemical shifts of the esters ROVO3H− are one half the chemical shift of the diesters (RO)2VO2− when those shifts are given relative to −559 ppm. This effect is independent of whether the signals are to high or low field of −559 ppm and the additivity extends to mixed ligand systems. This value of −559 ppm is close but not equal to the chemical shift of the vanadate monoanion, H2VO41−, which is at −561 ppm. These results are at variance with arguments concerning the effects of ligand bulkiness on chemical shifts of vanadium(V) complexes.

9Be nuclear magnetic resonance spectroscopy trends in discrete complexes: an update

2020 ◽  
Vol 75 (5) ◽  
pp. 459-472 ◽  
Author(s):  
Jenna K. Buchanan ◽  
Paul G. Plieger
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Solution Nmr ◽  
Resonance Spectroscopy ◽  
Coordination Numbers ◽  
Solution Nmr Spectroscopy ◽  
Beryllium Complexes

Abstract9Be solution NMR spectroscopy is a useful tool for the characterisation of beryllium complexes. An updated comprehensive table of the 9Be NMR chemical shifts of beryllium complexes in solution is presented. The recent additions span a greater range of chemical shifts than those previously reported, and more overlap is observed between the chemical shift regions of four-coordinate complexes and those with lower coordination numbers. Four-coordinate beryllium species have smaller ω1/2 values than the two- and three-coordinate species due to their higher order symmetry. In contrast to previous studies, no clear relationship is observed between chemical shift and the size and number of chelate rings.

scholarly journals Trends in NMR Structural Elucidation Of Polycyclic Cages, Namely: Adamantane, Pentacycloundecane and Trishomocubane

2021 ◽  
Vol 75 ◽  
Author(s):  
Monsuru T. Kelani ◽  
Darcelle Dieudonné ◽  
Kornelia J. Skowron ◽  
Clayton Pedigo ◽  
Thavenden Govender ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Structure Elucidation ◽  
Structural Elucidation ◽  
Polycyclic Compounds ◽  
Nuclear Magnetic

ABSTRACT Advances in Nuclear Magnetic Resonance (NMR) spectroscopy is a cornerstone in structure elucidation of polycyclic 'cage' scaffolds. Due to the compactness of these compounds, much overlap, as well as unique through-space and bond NMR interactions are frequently observed. This review serves as a guide for the NMR elucidation of future derivatives by providing some of the typical and relevant aspects of the characteristic trends, substituent patterns and chemical shift behaviour for the identification of the polycyclic structures, namely adamantane, pentacycloundecane and trishomocubane derivatives. Keywords: adamantane, NMR elucidation, pentacycloundecane, polycyclic compounds, trishomocubane

scholarly journals About Nuclear Magnetic Resonance Spectroscopy

2019 ◽  
Vol 5 (5) ◽  
pp. 19-24
Author(s):  
V. Shvannikov
Keyword(s):  
Organic Chemistry ◽  
Nuclear Magnetic Resonance ◽  
Organic Matter ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Resonance Spectroscopy ◽  
General Terms ◽  
Synthetic Chemist ◽  
Main Components

The paper deals with the main components of NMR spectroscopy, namely: terminology (chemical shift, multiplicity, and so on) and some examples of software additions (COSY, HECTOR). The theme of this work is aimed at students in the profile of organic chemistry, it allows you to get acquainted with the phenomenon of NMR (in General terms) and decoding spectra without deepening into quantum chemistry and physics. This improves communication and minimizes misunderstandings between the synthetic chemist and the spectroscopic chemist, as this method is one of the most commonly used in determining the structure of organic matter (does not violate the integrity of the carbon skeleton and prevents fragmentation).

scholarly journals Diversely Responsive Turn-On Fluorescent Cyclodextrin Chemosensors: Guest Selectivities and Mechanism Insights

Chemosensors ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 48
Author(s):  
Hiroshi Ikeda
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Hydrogen Bonds ◽  
Fluorescence Intensity ◽  
Organic Molecules ◽  
Bulk Water ◽  
Fluorescent Chemosensors ◽  
Molecular Mechanics Calculations ◽  
Turn On

Chemosensors have attracted considerable attention among the numerous strategies for detecting organic molecules in water. A turn-off mechanism was previously employed for the construction of a cyclodextrin (CD) chemosensor. This mechanism is greatly effective but has several shortcomings. In order to overcome these shortcomings, new fluorescent chemosensors NC0αCD, NC0βCD, and NC0γCD, which were (7-nitrobenz-2-oxa-1,3-diazol-4-yl)amine-modified α-CD, β-CD, and γ-CD, respectively, were prepared. Their guest selectivities were different from those of previously reported CD chemosensors. Here, the mechanism of new CD chemosensors was investigated using nuclear magnetic resonance (NMR) spectroscopy and molecular mechanics calculations. The fluorescence intensity of NC0βCD and NC0γCD slightly decreased and largely increased, respectively, upon the addition of ursodeoxycholic acid as a guest. This is due to the fact that the fluorophore of NC0βCD moved away to the hydrophilic bulk water to form hydrogen bonds between the host and the guest, while the fluorophore of NC0γCD remained located at the primary hydroxy side of the γ-CD unit to form a stable inclusion complex with hydrogen bonds between the fluorophore and the guest. NC0αCD also acted as a turn-on chemosensor for small guests, which could not be detected by the previous CD chemosensors. The motion restriction of the fluorophore through the generation of inclusion complexes could also contribute to increase in fluorescence intensity.

The Lewis acid complexes of α,β-unsaturated carbonyl and nitrile compounds. A nuclear magnetic resonance study

1982 ◽  
Vol 60 (6) ◽  
pp. 801-808 ◽  
Author(s):  
Ronald F. Childs ◽  
D. Lindsay Mulholland ◽  
Alan Nixon
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Lewis Acid ◽  
Lewis Acids ◽  
Acid Group ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
C Nmr

1:1 Complexes of a range of Lewis acids with crotonaldehyde (1) have been systematically investigated by 1H and 13C nmr spectroscopy. Lewis acids employed were: BF3, BCl3, BBr3, SnCl4, TiCl4, SbCl5, AlCl3, EtAlCl2, Et2AlCl, Et3Al2Cl3, and Et3Al. Chemical shift changes in 1H nuclei remote from the Lewis acid group were found to be remarkably regular and consistent. The study has been extended to tiglaldehyde (2), pent-3-en-2-one (3), cyclohexenone (4), methyl crotonate (5), and crotonitrile (6) and the relationships between the chemical shift differences associated with complexation of these have been explored.

Conductivity Studies of Schiff Base Ligands Derived from O-Phenylenediamine and Their Co(II) and Zn(II) Complexes

2015 ◽  
Vol 12 (2) ◽  
pp. 13
Author(s):  
Muhamad Faridz Osman ◽  
Karimah Kassim
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Fourier Transform ◽  
Schiff Base ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Impedance Spectroscopy ◽  
Ftir Spectroscopy ◽  
Coordination Complexes ◽  
Frequency Range ◽  
Schiff Base Ligands

The coordination complexes of Co(II) and Zn(II) with Schiff bases derived from o-phenylenediamine and substituted 2-hydroxybenzaldehyde were prepared All compounds were characterized by Fourier transform infrared (FTIR) spectroscopy and Nuclear magnetic resonance (NMR) spectroscopy elemental analyzers. They were analyzed using impedance spectroscopy in the frequency range of 100Hz-1 MHz. LI and L2 showed higher conductivity compared to their metal complexes, which had values of 1.3 7 x 10-7 and 6.13 x 10-8 S/cm respectively. 

Biological NMR Spectroscopy

1997 ◽  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
State Of The Art ◽  
Critical Assessment ◽  
Resonance Spectroscopy ◽  
History Of ◽  
Structure Of Proteins

This book presents a critical assessment of progress on the use of nuclear magnetic resonance spectroscopy to determine the structure of proteins, including brief reviews of the history of the field along with coverage of current clinical and in vivo applications. The book, in honor of Oleg Jardetsky, one of the pioneers of the field, is edited by two of the most highly respected investigators using NMR, and features contributions by most of the leading workers in the field. It will be valued as a landmark publication that presents the state-of-the-art perspectives regarding one of today's most important technologies.

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