Synthesis and Photophysical Studies of Arenes Appended with Electron Donor Acceptor Functionalities

Abstract

Donor-acceptor substituted aromatic systems are significant push-pull systems due to their readily modifiable structure together with outstanding and unique photophysical and electrochemical capabilities. There are several applications for these compounds, including biological imaging, chemosensors, organic electronics such as dye sensitized solar cells, organic photovoltaics, and organic light emitting diodes, among others. In our current research work, we have utilized the ring transformation methodology of 2H-pyran-2-ones to design and develop simple and economical syntheses of fluorescent D-and#960;-A aromatic systems showing remarkable photophysical properties. In the present study, an efficient, base mediated ultrasound assisted transition metal free synthesis of a new series of linear prenylarenes exhibiting blue fluorescence, which can be endorsed as important synthetic intermediates in organic and medicinal chemistry, was developed. In the ring transformation process of 2H-pyran-2-ones, the role of styryl acetate as the carbanion source for the generation of functionalized 1,2-terphenyls was also explored. Further, the synthesis of highly crowded naphthyl based teraryls and quateraryls incorporated with donor and acceptor groups were established. Moreover, the ring transformation strategy was seamlessly used for the synthesis of D-A-D systems constructed by connecting cyano, the acceptor group, via an aryl linker with two cyclic amino groups, one of which was an N-phenylpiperazine moiety, a critical structural unit in a number of pharmacologically active compounds. In addition to being economical and requiring no metal reagents, the aforementioned synthetic transformation processes are extremely simple to operate. Further, the photophysical properties of all the synthesised compounds such as absorption and emission, with a focus on the ICT-based solvatochromic fluorescence emission were studied. Quantum yield, optical band gap and Stokes shift were also determined.