Dimeric cyanopyridine with methylenebis(oxy)-based linker: A tactic to luminescent molecules exhibiting room temperature liquid crystalline property

Abstract

The first example of luminescent, room temperature liquid crystalline molecules with methylenebis(oxy)-based linker, namely, 2,2'-(methylenebis(oxy))bis(4,6-bis(4-(alkyloxy)phenyl)nicotinonitrile) has been reported in the present work. The designed molecules have been synthesized using dichloromethane (DCM) as the reagent to obtain the methylenebis(oxy)-based linkers. The structural characterizations of the synthesized molecules were carried out by using ATR-IR, 1H NMR, 13C NMR, MALDI-TOF, and elemental analysis. Photophysical property examination of the molecules in the solution state indicated the deep blue emissive nature of the molecules with a relative quantum yield of about 27–32%. Further, electrochemical studies were performed on the molecules by using cyclic voltammetry and determined their underlying HOMO and LUMO energy levels as well as the associated band gaps. In contrast, DFT analysis was performed on the representative compound bearing methoxy groups in place of flexible alkoxy chains to obtain optimized geometry and further studied the distribution of electron density in its HOMO and LUMO energy levels. Furthermore, the liquid crystalline property examination revealed that all the molecules exhibited a smectic C phase upon cooling from isotropic temperature. Finally, the present study paves the way for the synthesis of dendrimer-type liquid crystals with methylenebis(oxy)-based linkers.