Synthesis, characterization and DFT studies of 6-bis(2-(thiazol-4-yl)-benzimidazol-1-yl)hexane hemihydrate crystal: Experimental and theoretical investigation

Abstract

Abstract 6-bis(2-(thiazol-4-yl)-benzimidazol-1-yl)hexane has been efficiently synthesized by direct alkylation of 2-(4-thiazolyl)benzimidazole with 1,6-dibromohexane via phase-transfer catalysis. The desired compound was obtained in high yield and its structural characterization was performed by FTIR and NMR spectroscopies. A suitable single crystal of the compound for X-ray structure analysis was obtained and analyzed. The organic salt 1,6-bis(2-(thiazol-4-yl)-benzimidazol-1-yl) hexane (Bis-TBZ 0.5H2O) crystallizes in the monoclinic space group I2/a (#15). The optimized geometries, IR frequencies, 1H and 13C NMR chemical shifts and frontier molecular orbital energies (HOMO, LUMO) of the compound have been calculated by Density Functional Theory at the B3LYP/6-311G++(d,p) level of theory. All the available theoretical results were compared with the experimental data. The X-ray parameters of the title compound agree with the theoretically obtained values. The computed vibrational wavenumbers, 1H and 13C NMR chemical shifts of the compound show good correlation with the corresponding experimental ones. Finally, the calculated HOMO and LUMO energies revealed that charge transfer occurs in the molecule.