Multi-functional colorimetric chemosensor for naked eye recognition of Cu2+, Zn2+ and Co2+ using new hybrid azo-pyrazole/pyrrolinone ester hydrazone dye

New colorimetric chemosensor(Ethyl(E)-4-(2-(3-methyl-4-((E)-phenyldiazenyl)-1H-pyrazol-5-yl)hydrazono)-5oxo-2-phenyl-4.5-dihydro-1H-pyrrole-3-carboxylate) (APHPES) was synthesized. This compound mainly based on a hybrid hydrazo/azo dye chromophoric system of pyrrolinone ester and azo-pyrazole moieties. The selectivity was investigated at two different pH 5 and 7. The solution of the prepared dye in ethanol changed from red to violet, olive and green with Co2+, Zn2+ and Cu2+ respectively at pH 7 while the APHPES works as a mono selective for copper cation at pH 5 and the color change to green. The structure of synthesized sensor APHPESwas confirmed using NMR, Mass spectra, IR spectra and elemental analysis. The detection limit for recognition of Co2+, Zn2+ and Cu2+ was investigated, showing high sensitivity towards the mentioned metal cations, which falls in the range of 0.59-0.98 mu M. The sensor also showing a significant color change from red to violet color in alkaline pH with two pKa values were recorded at 7.64 and 9.09. The reversibility and cycling index with EDTA as well as acid-base were studied. The binding ratio was studied by job's plot method. The binding mechanism was studied using HNMR, MS and IR spectra.