Synthesis of (tricyanofuran‐3‐ylmethylene)hydrazinyl thiazole‐containing chromophore: A study of its photophysical properties, solvatochromism, and TD‐DFT computations

Abstract The chromophore 2–2‐(3‐cyano‐5,5‐dimethyl‐4‐((2‐[thiazol‐2‐yl]hydrazono)methyl)‐furan‐2(5 H )‐ylidene)malononitrile ( TzHTCF ) was prepared by diazo‐coupling of diazotized 2‐aminothiazole with 3‐cyano‐2‐(dicyanomethylene)‐4,5,5‐trimethylfuran ( TCF ). The TzHTCF absorption solvatochromism, in different polarity solvents, demonstrated a Δ E max = +4.74 in which the positive sign implied the occurrence of a red shift and the TzHTCF lowest excited state was more polar than its ground state. In addition, the TzHTCF fluorescence spectrum produced a λ em in the 416–670 nm range and was more dependent on the solvent polarity than the absorption λ max , despite both exhibiting a red shift of 24 and 254 nm, respectively. To discover the Stokes shift ( behaviour of the TzHTCF derivative, Lippert–Mataga and linear solvation–energy relationship (LSER) formulations were utilized in which the LSER approach displayed better results than the Lippert–Mataga method ( R 2 = 0.9931). Furthermore, the LSER showed that the absorption and fluorescence solvatochromic behaviours were dependent on the solvent's hydrogen‐bond donor ( α ) and acceptor ( β ), along with the solvent's polarizability ( π *). Moreover, DFT calculations showed that TzHTCF has a planar configuration and its simulated absorption and emission spectra in dimethyl sulphoxide revealed that λ max primarily originated from the HOMO→LUMO and HOMO‐1→LUMO transitions, respectively.