Novel functional [4]helicenes through a photooxidation pathway. Investigation of the absorption and fluorescence in solution

Abstract

Novel functional [4]helicenes have been designed and synthesized, in 54%–72% overall yields, through an operational and simple two-step photochemical approach starting from various p-substituted phenylacetonitriles, and were characterized by NMR ($^{1}$H, $^{13}$C, and COSY) and FT-IR spectroscopies. UV–Vis absorption properties of these tetracyclic ${\pi }$-conjugated systems have been experimentally investigated in various solvents and their optical gap energy was estimated to be less than 3.28 eV. The photoluminescence properties of these molecules have been evaluated in solutions and an emission in the blue region of the visible spectrum was noted. The obtained results seem encouraging for the examination of such compounds as promising materials for optoelectronic applications.

Keywords

• [4]helicenes
• Photooxidation
• Photochemistry
• Absorption
• Photoluminescence