Spectroelectrochemical Investigation of 4-Dicyanomethylene 2,6-Dimethyl-4H-Pyran (DDP) Dye with Guanidine Hydrochloride (GuHCl) in Water

Interaction of guanidine hydrochloride (GuHCl) with 4-dicyanomethylene-2,6-dimethyl-4H-pyran (DDP) dye were investigated by photophysical and electrochemical techniques. An enhancement in the fluorescence intensity and formation of an isosbestic point revels that the ground state and excited state properties of DDP dye. The nature of interaction between DDP dye and GuHCl is predominantly through hydrogen-bonding even thoughelectrostatic interaction in aqueous phase operate. The existence of electrostatic interaction by current response function describes that the shift in anodic peak potential towards less positive value indicate electrostatic binding. The existence of more than one microenvironment of DDP dye in aqueous phase is elucidated by Electrochemical Impedence Spectroscopy (EIS) studies through Nyquist plots. These plots signify that there exist at least three different micro environments or dye existing in different fluorescence lifetimes with varying of amplitude. Fluorescence spectral techniques along with electrochemical studies are used as efficient tools to elucidate the nature of interaction of a water soluble probe with hydrogen-bonding solutes is elucidated in our study.