However, in the presence GSH, a new absorption peak emerged at λex = 525 nm (Figure (e)) with the emission at 545 nm (Figure (f)). The Michael type addition between the vinyl group and GSH in Bdpy2 (Figure ) disrupts the conjugated system extension, leading to an approximate blue shift in both the absorption and fluorescence bands. The reverse process for Bdpy2 was tracked by observing the subsequent reduction in the λex = 525 nm absorption upon addition of 0.5 mM and 1 mM of N-ethylmaleimide (NEM), which reacts with GSH irreversibly, to deplete GSH and then GSH levels were restored by adding more GSH (Figure (g)). Throughout the consumption of GSH and its subsequent restoration, the fluctuations in the absorbance closely mirrored the changes in GSH concentrations. This alignment underscores the remarkably reversible character of the interaction between compound Bdpy2 and GSH.