Experimental and theoretical approaches of molecular geometry and mesophase behaviour relationship of laterally substituted azopyridines

Abstract

ABSTRACTNew 10 laterally chloro azopyridine-based derivatives, with terminal alkoxy chain length varies between 6 and 16 carbons, were prepared. The mesophase behaviour was investigated for prepared homologues by differential scanning calorimetry and polarised light microscopy. Each homologous series differ from each other by the lateral attached Cl group in the ortho- or meta-position with respect to the ester carbonyl core in the central benzene ring. Elemental analyses, FT-IR, 1H NMR and C13 NMR spectroscopy were used for molecular structure confirmation of the prepared compounds. All prepared homologues were found to be nematogenic. Density functional theory theoretical calculations used to confirm the experimental data and the results are consistent with the experimental investigations. It was found that the nematic range and stability is influenced by the length of the alkoxy chain and the orientation of the lateral chloro group. Moreover, an experimental and theoretical comparative study between the Cl-lateral isomers with respect to the previously reported methyl lateral derivatives as well as the laterally neat one in determination of the type, the stability of the mesophase and the molecular geometry.