Nematic and smectic bithiophenes for UV sensing mechanism: Comparative calculations on different homologues

Abstract

Four liquid crystalline molecules in the homologus series of 5,5′-Bis-(alkylpyridinyl)-2,2′-bithiophenes (nPBTP with n = 7, 8, 10, 12) have been investigated for UV sensing mechanism. Optimization of these compounds has been carried out through hybrid functional B3LYP along with 6-31 + G (d) basis set based on the crystallographic parameters as input. The UV absorption spectra of the molecules have been calculated and the configuration interaction singles (CIS) approach has been employed to study the electronic transitions features along with excited states calculation with the help of semiempirical Hamiltonian ZINDO. The INDO/S + CI method has been implemented for the same for comparison of the results. Various spectral parameters associated have been reported. The HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies estimations, and the transition energies, the electron excitation nature concerning on the structural variations in the molecules are clarified. The results obtained suggest model UV sensing mechanism for full colour display applications. A comparison has been made between nematic and smectic systems.