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Does Urea Alter the Collective Hydrogen‐Bond Dynamics in Water? A Dielectric Relaxation Study in the Terahertz‐Frequency Region
Author(s) -
Samanta Nirnay,
Das Mahanta Debasish,
Kumar Mitra Rajib
Publication year - 2014
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201402696
Subject(s) - hydrogen bond , urea , terahertz radiation , relaxation (psychology) , debye , dielectric , chemistry , trimethylamine n oxide , chemical physics , hydrogen , materials science , molecule , trimethylamine , optoelectronics , organic chemistry , psychology , social psychology
Abstract We report the ultrafast collective hydrogen‐bond dynamics of water in the extended hydration layer of urea by using terahertz time‐domain spectroscopy in the frequency region of 0.3–2.0 THz. The complex dielectric function has been fitted using a Debye relaxation model, and the timescales obtained are in the order of approximately 9 ps and 200 fs for bulk water; this exhibits a considerable acceleration beyond the 4 M urea concentration and indicates a possible disruption in the collective hydrogen‐bonded water‐network structure, which, in turn, provides an indirect support for the water “structure‐breaking” ability of urea. With 5 M urea in the presence of different concentrations of trimethylamine‐ N ‐oxide (TMAO), it was found that these parameters essentially follow the trend observed for TMAO itself, which signifies that any possible disruption of the water structure by urea is outdone by the strong hydrogen‐bonding ability of TMAO, which explains its ability to revive urea‐denatured proteins to their respective native states.