Steroidal analogues of unnatural configuration. Part XI. Crystal and molecular structure of 3α,17α-dihydroxy-4,4,14α-trimethyl-19-nor-10α-pregn-5-ene-11,20-dione and a circular dichroism study of the conformation of the acetyl side-chain of the 17-hydroxy-isomers in solution

1977 ◽  
pp. 402-406 ◽  
Author(s):  
Pieter R. Enslin ◽  
Johan Coetzer ◽  
Gert J. Kruger
Keyword(s):  
Molecular Structure ◽  
Circular Dichroism ◽  
Crystal And Molecular Structure ◽  
Side Chain ◽  
Circular Dichroïsm

scholarly journals The Chiral 1:2 Adduct (S)S(S)C(−)589-Ethyl 2-Phenylbutyl Sulphide-Mercury (II) Chloride:(−)589[(S)S(S)C-Et(2-PhBu)S.(HgCl2)2]. Stereoselective Synthesis, Asymmetric Oxidation, Crystal and Molecular Structure and Circular Dichroism Spectra

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3398
Author(s):  
Paolo Biscarini ◽  
Ivano Bilotti ◽  
Francesco Ferranti ◽  
Alessia Bacchi ◽  
Giancarlo Pelizzi ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Circular Dichroism ◽  
Stereoselective Synthesis ◽  
Crystal And Molecular Structure ◽  
Cotton Effect ◽  
Coordination Polyhedra ◽  
Asymmetric Oxidation ◽  
Complex Ii ◽  
A Charge ◽  
Circular Dichroïsm

Optically active (−)589ethyl (S)-2-phenylbutyl thioether, (−)(S)C-Et(PhBu)S (I), and its new diastereoisomeric mercury (II) chloride adduct, 1:2, (−)[(S)S(S)C-Et(PhBu)S.(HgCl2)2]2, (II) were stereoselectively synthesized; the absorbance (UV) and circular dichroism (CD) spectra were measured and the crystal and molecular structure of complex (II) was determined by single-crystal X-ray diffraction. Two different Hg centres are present whose coordination environments are built by two short bonds to chloride ligands in one case, and to one chloride and one sulphur in the other one. These originate digonal units. Electroneutrality is achieved by a further chlorine, which can be considered prevalently ionic and bonded to the two Hg centres, forming square bridging systems nearly perpendicular to the digonal molecules. The coordination polyhedra can be interpreted as 2 + 4 tetragonally-compressed octahedra with the four longer contacts lying in the equatorial plane. IR spectroscopic data are consistent with the presence of one bent and one linear Cl–Hg–Cl moiety. The absolute configurations at both stereogenic centres of the formed diastereoisomeric complex (II) are (S). The (S)S absolute configuration at the stereogenic sulphur atom bonded to the mercury(II) atom in complex (II) has been related with the negative Cotton effect assigned in its circular dichroism (CD) spectrum to a charge-transfer transition at ca. 230 nm. The stereoselective oxidation of (I) and (II) with hydrogen peroxide, induced by the stereogenic carbon atom (S)C of the enantiopure sulphide, gave (−)598ethyl (S)C-2-phenylbutyl(S)S-sulphoxide, (−)598[(S)S(S)C-Et(PhBu)SO], (III), having 18.1% de. Oxidations carried out in the presence of a 200 molar excess of mercury(II) chloride gave (−)598ethyl (S)C-2-phenylbutyl(R)S-sulphoxide, (−) 598[(R)S(S)C-Et(PhBu)SO], (IV) with 31% de, showing the cooperative influence of mercury(II) chloride on the selectivity of the oxidation reaction.

scholarly journals A Raman, SERS and UV-circular dichroism spectroscopic study of N-acetyl-l-cysteine in aqueous solutions

2019 ◽  
Vol 43 (38) ◽  
pp. 15201-15212 ◽  
Author(s):  
R. A. Cobos Picot ◽  
M. Puiatti ◽  
A. Ben Altabef ◽  
R. J. G. Rubira ◽  
S. Sanchez-Cortes ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Circular Dichroism ◽  
Aqueous Solutions ◽  
Spectroscopic Study ◽  
Electronic Properties ◽  
Structural Properties ◽  
Amine Groups ◽  
Circular Dichroïsm

The aim of this work is to evaluate the vibrational and structural properties of N-acetyl-l-cysteine (NAC), and its molecular structure and electronic properties in relation to the action of thiol and amine groups at different pH.

Crystal and molecular structure of heptacain hydrochloride

1986 ◽  
Vol 51 (2) ◽  
pp. 264-270 ◽  
Author(s):  
František Pavelčík ◽  
Milan Remko ◽  
Jozef Čižmárik ◽  
Jaroslav Majer
Keyword(s):  
Molecular Structure ◽  
Least Squares Method ◽  
Crystal And Molecular Structure ◽  
Three Dimensional ◽  
Chair Conformation ◽  
Piperidine Ring ◽  
Side Chain ◽  
Ring Plane ◽  
Benzene Ring Plane ◽  
Carbamate Group

The crystal and molecular structure of heptacain hydrochloride was determined from three-dimensional diffractometric data. The carbamate group was found to be rotated out of the benzene ring plane by 15.5°, whilst the piperidine ring is in a more stable chair conformation. The heptyloxy side chain is in a stable all-trans conformation. The structure was refined by the full matrix least-squares method to a final R value 0.1127 for the observed reflections.

Molecular Structure of Guanine-Quartet Supramolecular Assemblies in a Gel-State Based on a DFT Calculation of Infrared and Vibrational Circular Dichroism Spectra

Langmuir ◽  
2008 ◽  
Vol 24 (14) ◽  
pp. 7520-7527 ◽  
Author(s):  
Vladimír Setnička ◽  
Jakub Nový ◽  
Stanislav Böhm ◽  
Nampally Sreenivasachary ◽  
Marie Urbanová ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Circular Dichroism ◽  
Dft Calculation ◽  
Supramolecular Assemblies ◽  
Vibrational Circular Dichroism ◽  
Circular Dichroism Spectra ◽  
Guanine Quartet ◽  
Circular Dichroïsm
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