HYDROGEN BOND AND THE STRUCTURES OF 2-, 3- AND 4-BIPHENYLMETHANOLS
L. M. Babkov, N. A. Davydova, K. E. Uspenskii
Keywords: IR spectrum, structure, hydrogen bond, Н-complex, simulation, density functional theory, triclinic modification, monoclinic modification, glass phase, liquid
Pages: 419-426
Abstract
Density functional theory (B3LYP/6-31G*) is applied to calculate structures, energy, dipole moment, polarizability, frequencies of normal vibrations in the harmonic approximation and intensities in vibrational spectra of 2-, 3-, and 4-biphenylmethanol molecules and their H-complexes that can form in crystalline, amorphous, and liquid phases. Based on the analysis of simulation results, the effect of the position of a methanol group in the molecule on its vibrational spectrum is discussed. The structure forming role of a hydrogen bonds in biphenylmethanols and the possibility of realization of two polymorphic modifications in 2-biphenylmethanol are stated. These modifications are: metastable monoclinic, in which each of four molecules of the unit cell is a link of a chain Н-associate; and stable triclinic, in which four molecules of the unit cell organize an Н-complex in the form of a cyclic tetramer. It is found that crystalline samples of 3- and 4-biphenylmethanols consist of chain Н-associates. A glass-like sample of 2BPhM being a mixture of Н-complexes consisting of cyclic tetramers and chain associates contains crystalline nuclei of triclinic and monoclinic polymorphous modifications in the supercooled state. In a liquid sample of 2BPhm, chain Н-associates and free molecules are realized.
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