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DFT conformational studies of the HI‐6 molecule
Author(s) -
Silva Gustavo R.,
Borges Itamar,
FigueroaVillar Jose D.
Publication year - 2005
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.20700
Subject(s) - chemistry , oxime , protonation , pyridinium , computational chemistry , molecule , side chain , density functional theory , stereochemistry , medicinal chemistry , organic chemistry , ion , polymer
A systematic study of the oxime HI‐6 [1‐(2‐hydroxyiminomethyl‐1‐pyridinium)‐1‐(4‐carboxy‐aminopyridinium)dimethyl ether] hydrochloride, which is one of the most promising antidotes against soman intoxication, was carried out using density functional theory with the B3LYP (Becke, Lee, Yang, and Parr) method and the 6‐31+G*, 6‐31+G*, and 6‐31+G** basis sets. Rotational barriers, equilibrium geometries, and charge distributions were calculated in order to investigate the role of the side chain for the larger oximes used as antidotes in the treatment of neurotoxic organophosphate poisoning. Also reported is the comparison between HI‐6 and pralidoxime (2‐PAM), a smaller oxime previously studied in our research group. It is shown that conformation minima for the protonated E isomer do not depend on the size of the side chain; on the other hand, this effect has a pronounced influence on the protonated Z isomer. For the unprotonated isomers, other effects, such as electrostatic interactions and resonance, should be taken into account in their conformational analysis. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005