Abstract
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 Delta 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 lambda(em) in the 416-670 nm range and was more dependent on the solvent polarity than the absorption lambda(max), despite both exhibiting a red shift of 24 and 254 nm, respectively. To discover the Stokes shift ( increment nu over bar )$$ \Delta \overline{\nu}\Big) $$ 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 (alpha) and acceptor (beta), along with the solvent's polarizability (pi*). Moreover, DFT calculations showed that TzHTCF has a planar configuration and its simulated absorption and emission spectra in dimethyl sulphoxide revealed that lambda(max) primarily originated from the HOMO -> LUMO and HOMO-1 -> LUMO transitions, respectively.