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Hydrogen Bonds and Ionic Forms versus Polymerization of Imidazole at High Pressures
journal contribution
posted on 2015-01-08, 00:00 authored by Bharat
Bhooshan Sharma, Ashok
K. Verma, Susy Thomas, Chitra Murli, Surinder M. SharmaImidazole (C3H4N2) is an important
biomaterial for material research and applications. Our high-pressure
Raman spectroscopic investigations combined with ab initio calculations on crystalline imidazole suggest that C–H---X
(X = N, π) and N–H---N intermolecular hydrogen bonding
interactions largely influence the nature of its structural and polymeric
transformations under pressure. At pressures around ∼10 GPa,
the reduction in the N---N distances close to the symmetrization limit
and the emergence of the spectral features of the cationic form indicate
the onset of proton disorder. The pressure-induced strengthening of
the “blue-shifting hydrogen bonds” C–H---X (X
= N, π) in this compound is revealed by the Raman spectra and
the ab initio calculations. No polymer phase was
retrieved on release from the highest pressure of 20 GPa in this study.