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

The chromophore 2-2-(3-cyano-5,5-dimethyl-4-((2-[thiazol-2-yl]hydrazono)methyl)-furan-2(5H)-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 ΔE  = +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 in the 416-670 nm range and was more dependent on the solvent polarity than the absorption λ , 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  = 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 primarily originated from the HOMO→LUMO and HOMO-1→LUMO transitions, respectively.