Manifestation of the Even-Odd Effect in the Molecular Parameters of p-n-Alkyloxybenzoic Acids and their Pyridine Esters

Abstract
The manifestation of alternation in changing of molecular parameters values of p-n-alkyloxybenzoic acids and their pyridine esters versus the number of carbon atoms in radicals was studied by DFT/B3LYP/cc-pVTZ method. It was found that molecular characteristics, such as geometric parameters (length , width, volume, rotational constant), as well as the components of the dipole moment exhibit even-odd effect comparable to that observed for the N &arrow; I phase transition temperature, while this effect was not observed in the values of total electron energy E and the thermodynamic functions G and H. As an example of homologous series of the p-n-alkyloxybenzoic acids and the pyridine esters of p-n-alkyloxybenzoic acids it was shown that the geometric structure of the individual compounds is one of the main reasons of even-odd effect manifestation in experimental macrocharacteristics of the processes, occurring in liquid crystal systems.

Keywords: even-odd effect, liquid crystals, p-n-alkyloxybenzoic acids, pyridine esters of p-n-alkyloxybenzoic acids, molecular characteristics, quantum chemical calculations