Synthesis, photophysical properties and nonlinear response of a bisquinoline A-D-A with aggregation-induced emission for potential application in optoelectronic devices

The present work reports the synthesis and characterization of a bisquinoline (BQT) with very attractive aggregation-induced emission (AIE) and optical nonlinear response. BQT was characterized by FTIR spectroscopy and mass spectrometry to confirm the product obtained. Linear optical characterization was performed using UV-Vis and fluorescence spectrophotometry. Maximum absorption and emission wavelengths of 408 nm and 539 nm, respectively, were determined in solution; the optical band gap on the film is 1.95 eV. BQT exhibits aggregation-induced emission (AIE), a property exhibited by some fluorescent molecules that broaden the range of applications in which they can be used. BQT exhibits two-photon absorption with a negative nonlinear refractive index. This response is associated with the charge transfer processes that favour the A-D-A architecture of the molecule. Their HOMO and LUMO energy levels (-5.39 eV and -3.67 eV, respectively) and electrochemical band gap (-1.72 eV) were determined by cyclic voltammetry; these values indicate that BQT is an attractive organic semiconductor which energy levels could match those required for photovoltaic applications. The results suggest that BQT is an attractive material for its application in optoelectronic devices such as OLEDs and nonlinear optical applications.