'Long-distance' H/D isotopic self-organization phenomena in scope of the infrared spectra of hydrogen-bonded terephthalic and phthalic acid crystals
| Autor: | Barbara Hachuła, Faisal Abdulaziz Al-Agel, Najeh Rekik, Henryk T. Flakus, Jakub T. Hołaj-Krzak |
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| Rok vydání: | 2017 |
| Předmět: |
Terephthalic acid
Hydrogen Hydrogen bond Stereochemistry chemistry.chemical_element Infrared spectroscopy Aromaticity 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Atomic and Molecular Physics and Optics 0104 chemical sciences Analytical Chemistry Isotopomers chemistry.chemical_compound Crystallography Phthalic acid chemistry Molecule 0210 nano-technology Instrumentation Spectroscopy |
| Zdroj: | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 173:65-74 |
| ISSN: | 1386-1425 |
| DOI: | 10.1016/j.saa.2016.08.051 |
| Popis: | 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 h 6 -TAC isotopomer. In the case of the d 4 -TAC derivative the isotopic exchange process occurred noticeably more effectively. In contrast, both isotopomers of PAC, h 6 and d 4 , 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) 2 cycles. This leads to an additional stabilization of h 6 –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 C H 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. |
| Databáze: | OpenAIRE |
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