Further, the inhibition of a-PET process due the formation of PTE-EAꓵCu 2+ complex presented remarkable enhancement in the fluorescence intensity by keeping unchanged the emission maxima at 520 nm and weakly fluorescent solution become highly bright-green fluorescent. Thus PTE-EA efficiently performed as both colorimetric and fluorescent "light-up" probe by vanquishing two conventional photophysical phenomena including ICT and a-PET for the detection of Cu 2+ in mixed aqueous-organic solutions with nano-molar detection limits. The response of both mechanisms for the detection behavior of PTE-EA towards Cu 2+ is also well explained diagrammatically (Figure ).