"Long-distance" H/D isotopic self-organization phenomena in scope of the infrared spectra of hydrogen-bonded terephthalic and phthalic acid crystals.
This paper deals with the experimental and theoretical studies of abnormal properties of terephthalic acid (TAC) and phthalic acid (PAC) crystals manifested in the H/D isotopic exchange. The widely utilized deuteration routine appeared to be insufficiently effective in the case of the h6-TAC isotopomer. In the case of the d4-TAC derivative the isotopic exchange process occurred noticeably more effectively. In contrast, both isotopomers of PAC, h6and d4, appeared much more susceptible for deuteration. A theoretical model was elaborated describing "long-distance" dynamical co-operative interactions involving hydrogen bonds in TAC and PAC crystals. The model assumes extremely strong dynamical co-operative interactions of hydrogen bonds from the adjacent (COOH)2cycles. This leads to an additional stabilization of h6-TAC molecular chains. The interaction energies affect the chemical equilibrium of the H/D isotopic exchange. The model predicts a differentiated influence of the H and D atoms linked to the aromatic rings on to the process. In this approach the totally-symmetric CH bond stretching vibrations and the proton stretching totally symmetric vibrations couple with the π-electronic motions. It was also shown that identical hydrogen isotope atoms, H or D, in whole TAC molecules, noticeably enlarge the energy of the dynamical co-operative interactions in the crystals, in contrast to the case of different hydrogen isotopes present in the carboxyl groups and linked to the aromatic rings. The "long-distance" dynamical co-operative interactions in PAC crystals were found of a minor importance due to the electronic properties of PAC molecules.
Institute of Chemistry, University of Silesia, Katowice 40-006, Poland. Electronic address: flakus@ich.us.edu.pl.
Henryk T
HT
Flakus
Institute of Chemistry, University of Silesia, Katowice 40-006, Poland. Electronic address: barbara.hachula@us.edu.pl.
Barbara
B
Hachuła
Institute of Chemistry, University of Silesia, Katowice 40-006, Poland.
Jakub T
JT
Hołaj-Krzak
Physics Department, College of Science, Aljouf University, P. O. Box 2014, Sakaka, Saudi Arabia.
Faisal A
FA
Al-Agel
Physics Department, Faculty of Science, Ha'il University, P. O. Box 2440, 81451 Ha'il, Saudi Arabia; Laboratoire de Physique Quantique, Faculté des Sciences de Monastir, 5019 Monastir, Tunisia. Electronic address: rekik@ualberta.ca.
Najeh
N
Rekik
H/D isotopic self-organization phenomena; Hydrogen bond; Infrared spectra; Terephthalic and phthalic acid crystals