An evaluation of the chalcogen atom effect on the mesomorphic and electronic properties in a new homologous series of chalcogeno esters

A series of chalcogeno esters 1a, 6a and 6b have been synthesized in a straightforward manner. Polarized-light optical microscopy (POM) and differential scanning calorimetry (DSC) showed that these chalcogeno esters displayed a wide nematic range of mesophase. In addition, UV-Vis in solution (ca.10-5 mol L-1) was applied in order to obtain the HOMO-LUMO gap for further comparison with the theoretical results. The calculated values to the HOMO-LUMO gap are in excellent agreement with the experimental results, where the electronegativity of the heteroatom (O, S and Se) seems to play a fundamental role in the absorption maxima location. A theoretical study was performed using a DFT/B3LYP calculations with Becke's three-parameter hybrid method applying the Lee-Yang-Parr functional correlation (B3LYP) with DGDZVP basis set in order to evaluate some physical chemistry data related with mesomorphic and spectral eletronic properties. By synthesizing these compounds we were able to get a more precise description about the influence of the chalcogen atom on the mesomorphic and photophysical properties.