Luciferin is a chemical compound found in some living organisms. It is responsible for producing light. Due to the importance of luciferin in various applications, in this study, a series of new luciferin analogues are synthesised and characterized using different techniques, including: proton nuclear magnetic resonance (1H-NMR), carbon-13 nuclear magnetic resonance (13C-NMR), Correlation spectroscopy (COSY), Heteronuclear single quantum coherence (HSQC), Electron impact (EI) mass spectra, and Fourier transform infrared spectroscopy (FTIR). These compounds are synthesized by reacting cysteine monohydrate hydrochloride with aryl nitrile derivatives through the click reaction, using sodium bicarbonate and reflux for two days, with high yields and purity. The thiazole motif is also prepared by reacting the aldehyde with 2-aminothiophenol using urea nitrate as a catalyst with high yield, rapid, easy, quick isolation, and solvent-free. The Stokes shift for their analogues was studied and calculated. The Tauc formalism calculated the energy band gaps. The Stokes shift and the energy band gaps were almost the same value for the thiazoline motifs C3, C4, C5, and C6, which is attributed to the same chemical structures for them. Still, there is a difference for benzothiazole motifs T4, T6, as a consequence of different substitutions.
Wael Sadiq Hanoon, Raed Kadhim Zaidan, Basil Ali Abdullah and Widad S. Hanoosh