Theoretical study on ultraviolet profile and chemical reactivity descriptors of fluorinated liquid crystals: Effect of end chain length and substituent

The electronic transitions in the ultraviolet (UV) region of nematic 4-(3,4,5-trifluorophenyl)-4-alkylbicyclohexyl (3FPnBCH) molecules with propyl (3FP3BCH), and pentyl (3FP5BCH) have been studied. The UV spectra of these molecules have been simulated using the TDDFT/B3LYP/6-31+G (d) method. Molecular charge distribution has analyzed based on Mulliken and Loewdin atomic charges for each molecule. The absorption spectra, HOMO and LUMO energies corresponding to the electronic transitions in the UV region have been reported. Excited states have been calculated via CI-singles (CIS) with semiempirical Hamiltonian ZINDO. Further, intensity profile analysis has been carried out to detect the highest possible absorption wavelength. Global chemical reactivity descriptors and effect of end chain length on all these parameters has been studied. Similar studies have been carried out for these molecules with respect to boron substitution (3BPnBCH; n=3, 5). These computations offer deeper understanding in UV stability, reactivity, and kinetic stability of these molecules.