H/D isotopic recognition in hydrogen bonded systems: H/D isotopic self-organization effects in the IR spectra of the hydrogen bond in 2-methylimidazole crystals.
Polarized IR spectra of H12(3)45 2-methylimidazole and of its H1D2(3)45, D1H2(3)45 and D12(3)45 deuterium derivative crystals are reported and interpreted within the limits of the "strong-coupling" theory. The spectra interpretation facilitated the recognition of the H/D isotopic "self-organization" phenomenon, which depends on a non-random distribution of protons and deuterons in the lattices of isotopically diluted crystal samples. The H/D isotopic "self-organization" mechanism engaged all four hydrogen bonds from each unit cell. These effects basically resulted from the dynamical co-operative interactions involving adjacent hydrogen bonds in each hydrogen bond chain. A weaker exciton coupling involved the closely spaced hydrogen bonds; each belonging to a different chain of associated 2-methylimidazole molecules. The high intensity of the narrow band at ca. 1880cm(-1) was interpreted as the result of coupling between the γ(N-H⋯N) proton bending "out of plane" vibration overtone and the ν(N-H) proton stretching vibration.
Institute of Chemistry, University of Silesia, 9 Szkolna Street, Pl-40-006 Katowice, Poland. flakus@ich.us.edu.pl
Henryk T
HT
Flakus
Barbara
B
Hachuła
Agnieszka
A
Stolarczyk
D003460:Crystallization; D003903:Deuterium / Q000737:chemistry; D006860:Hydrogen Bonding; D007093:Imidazoles / Q000737:chemistry*; D013055:Spectrophotometry, Infrared / Q000379:methods
D007093:Imidazoles; D003903:Deuterium; C032655:2-methylimidazole