Vacancies in the molecular crystal of 2-(2'-hydroxyphenyl)benzothiazole

Abstract

Structure of molecular units is calculated for the periodic model corresponding to the crystal lattice of 2-(2'-hydroxyphenyl)benzothiazole with vacancies. 2-(2' -hydroxyphenyl)benzothiazole is a luminescent organic substance undergoing excited state intramolecular proton transfer. The calculations are performed with density-functional based tight-binding methods usding Van der Waals interaction empirical correction. It is found that the dihedral angles formed by benzothiazole and phenol parts of the molecules deviate in the vicinity of the vacancy. The vacancy provides enough space for non-planar conformation of the molecules in the ground state. At the same time the increase in energy of the periodic structure with the vacancies caused by appearance of the non-planar conformation is larger than the corresponding increase in the isolated molecule.