Novel π-extended polycyclic chromenopyridines: Synthesis, DFT, electrochemical, and thermogravimetric evaluation

Abstract

Polycyclic aromatic hydrocarbons (PAHs) doped with heteroatoms such as thiophene, carbazole, and boron-dipyrromethene (BODIPY) have attracted increased attention because of their excellent optoelectronic properties in addition to the robust skeletons required for the construction of efficient organic electronics. Herein, novel π-extended polycyclic chromenopyridines 3a-d, 5, and 7 were synthesized via base-catalyzed cascade reaction of 3-cyano-7,8-benzochromone 1 with acetonitrile derivatives 2a-d, ethyl chloroacetate 4, and phenylpyrazolone 6 in very good to excellent yields. Density functional theory (DFT) calculation and electrochemical evaluation of compounds 3a-d, 5, and 7 revealed a decreased energy gap (Eg) compared to the precursor 3-cyanochromone 1 indicating their superior semiconducting and light-harvesting abilities. In addition, the observed thermal stability of chromenopyridines 3a-d, 5, and 7 with maximum weight loss at temperatures between 301.72 and 557.28 °C qualified them for wide organic electronic applications.