An easily accessible internal charge transfer chemosensor exhibiting dual colorimetric and luminescence switch on responses for targeting Cu2+

A new internal charge transfer probe, MIZON was synthesized by condensing Michler's ketone with 4-(N,N′-dimethylamino)benzhydrazide. The spectrophotometric and fluorimetric titrations with metal ions of biological and environmental importance were performed in H2O–CH3CN (1:1 v/v) system buffered by Tris–HCl, pH = 7.4 ± 0.1. The probe, MIZON was found to interact selectively with Cu2+, inducing remarkably high absorbance red shift by 240 nm and 11-fold enhancement in the emission intensity. In contrast, several other metal ions, viz. Li+, Na+, K+, Ca2+, Mg2+, Ba2+, Pb2+, Co2+, Cd2+, Zn2+, Ni2+ and Hg2+, even at substantially higher concentration than Cu2+, did not exert significant perturbation in the photophysical profile of the probe. The detection limit of Cu2+, calculated from the more sensitive fluorescence data was found to be 5.5 × 10−7 M. Potential, therefore is clearly available in MIZON to detect Cu2+ in micromolar range via dual visible color change from yellow to green and fluorescence switch-on response.