Electron-Withdrawing Substituted Quinazoline Push-Pull Chromophores: Synthesis, Electrochemical, Photophysical and Second-Order Nonlinear Optical Properties

Abstract

A series of chromophores bearing 4-cyanoquinazoline, 2-(4-cyanophenyl)quinazoline or 2-(4-trifluorophenyl)quinazoline electron-acceptor (A) and 5-(4-aminophenyl)thiophen-2-yl or 4-aminophenyl electron-donor (D) units has been designed. The influence of the electron-withdrawing substituent on the pyrimidine core as well as the nature of the amino electron donating group has been studied by cyclic voltammetry, UV/Vis and emission spectroscopy. Whereas 2-(4-cyanophenyl)quinazoline and 2-(4-trifluorophenyl)quinazoline derivatives are highly luminescent in chloroform solution, 4-cyanoquinazolines are poorly emissive. Interestingly all compounds are luminescent in the solid state with the emission ranging from blue to red. The second order nonlinear optical properties were studied using electric field induced second harmonic generation (EFISH) method. Quantum-chemical calculations corroborate the aforementioned experimental results.