Synthesis, DFT, and photophysical studies of substituted pyridine carbonitrile derivatives

Abstract

The synthesis and photophysical study of cyanopyridine derivatives of chalcones are very fascinating because of their excellent fluorescent nature in solid and solution states. Their emission properties accomplish the need for fluorescent probes for optoelectronic applications. Herein we synthesized the cyanopyridine derivative PC (1-3) by hetero cyclization of chalcone using malononitrile. The structure was confirmed by spectroscopic (NMR, FTIR, and, Mass) and DFT data. The solid-state emission showed the emission in the UV region (250-400 nm) for PC1 and PC2. The PC3 showed feeble emission both in solid and solution states. The corresponding chloro and thiophene derivatives showed good emission intensity because of Intramolecular Charge Transfer (ICT) enhancement. The Commission Internationale de l'Elcairage (CIE) color coordinates showed blue emission in the solution state. The emission maxima were centered at 391, 385, and 487 nm for PC1, PC2, and PC3 respectively. There are two absorption bands in the range of 265-309 nm and 323-379 nm due to π-π* and n-π* transitions. The synthesized molecules have shown broad and high solid-state emission with good fluorescence quantum efficiency and these attributes have been extensively leveraged in the fabrication of optical sensors, imaging substances, and organic light-emitting diodes.