Facile access to furo[2′,3′:4,5]pyrido[3,2,1-jk]carbazol-5-ones as blue emitters: photophysical, electrochemical, thermal and DFT studies

Abstract

A series of thermally stable (up to ≤339°C) and blue fluorescent furo[2′,3′:4,5]pyrido[3,2,1-jk]carbazol-5-ones (FPCOs) with high quantum yields (Ø ≥ 0.75) are reported. These hybrid scaffolds have been synthesized from a bunch of Morita‐Baylis‐Hillman acetate of nitroalkenes and 4-hydroxy-6H-pyrido[3,2,1-jk]carbazol-6-one (HPCO) promoted by DABCO as an organobase at room temperature. All the new chemical structures were assigned by their spectroscopic techniques such as FT-IR, 1H NMR and 13C NMR, HRMS. The solvatochromic studies of targeted scaffolds exhibited blue shifts in absorption and emission spectra with increasing the polarity of solvents. Interestingly, higher quantum yields were also obtained in case of low polar solvents as well as products containing electron-donating groups. The density functional theory calculations indicated that electron-donating substituents led to the lower HOMO-LUMO gap, resulting in bathochromic shifts in absorption spectra. Moreover, chemical hardness, global softness and chemical potential descriptors of compounds are well-estimated. The nature of electronic transition of synthesized scaffolds was well addressed by TD-DFT calculations. In addition, by using NBO and surface analysis calculations, the most nucleophilic and electrophilic sites of title scaffolds were assigned. Interestingly, the cyclic voltammograms of all the FCPOs were shown only one irreversible reduction peak values (-0.62 V to -0.73 V). Therefore, promising charge carrier properties, good thermal robustness and electrochemical stability would make them potential candidates for electronic devices.