LAUSR

Thioxylated peptide bond in simple dipeptides and tripeptides is found to amend the structural, optical and redox properties of the same relying on the position of substitution (N- and C-terminals). The electronic structural investigations show that the geometrical parameters are found to be highly influenced by the thioxo substitution at N-terminus. However, the absorbance properties are influenced by thioxo substitution at C-terminal, where blue shifts in π–π* transitions are observed compared to unsubstituted one. Similarly, the cationization reveals that the substitution at C-terminal promotes the conformational shift. Further, the computational studies clearly indicate that the N-terminal substitution effects the ground state geometry, while substitution at other position influences the excited and redox properties. The observed conformation switches in C-terminal conformers have been proposed as a candidate for redox switch, where the states (neutral and cation) were probed using computed vibrational data and chemical shift values.