Synthesis and Photophysical Properties of α-Pyrone-fused-pyrido[3, 2,1-jk]carbazolone Derivatives : DFT/TD-DFT Insights

Abstract

The present paper discloses an interesting microwave-assisted solvent-free protocol for the synthesis of thermally stable, highly fluorescent pyrano[2′, 3′:4,5]pyrido[3, 2,1-jk]carbazole-5,8-diones in good to high yields with good quantum yields (Ø ≥ 0.70) through a [3+3] annulation reaction of aryl-substituted Morita-Baylis-Hillman acetates with a 4-hydroxy-6H-pyrido[3, 2,1-jk]carbazol-6-one in the presence of Hünig's base. The solvatochromic properties of synthesized compounds have been determined which showed blue shifts in absorption and emission spectra with increasing the polarity of solvents. Similarly, the higher quantum yields were also observed in case of non-polar solvents as compared to polar ones. Interestingly, the experimental results of photophysical properties were in good agreement with theoretical data obtained using B3LYP/6-311G++(d,p) level of theory. Furthermore, the synthesized chromophoric scaffolds exhibited good thermal stability (342-387 °C) and average fluorescence lifetime in the range of 2.011-2.139 ns for 408 nm, 2.268-2.277 ns for 428 nm. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim