Diaminomaleonitrile Schiff base with phenothiazine aldehyde as multimode chemosensor for copper ions and its application

Abstract

A diaminomaleonitrile and phenothiazine coupled probe P was synthesized and structurally characterized by FTIR, NMR, mass, and single-crystal X-ray diffraction analysis. The probe P crystallizes in a monoclinic P21/c space group and is very selective to Cu2+ ions in ACN: H2O (8:2, v/v). Probe P exhibits a visible color change from yellow-orange to colorless and turn-on blue fluorescence with Cu2+ ions. The probe P could form a 1:1 stoichiometry complex with Cu2+ ions with an estimated binding constant of 3.24 × 104 M−1. The binding mechanism was studied using the EPR, FTIR, ESI-mass, and DFT/TD-DFT calculations. The multimode probe P could detect Cu2+ ions down to 0.86 µM, 1.45 µM, and 5.68 nM by spectrophotometry, smartphone-integrated RGB, and spectrofluorometry methods, respectively. The probe P-loaded silica test strips were used qualitatively to recognize Cu2+ ions in a water medium. The dynamic response of probe P with Cu2+ and Na2EDTA was used to construct the molecular logic circuit. Also, probe P was used to detect Cu2+ ions in the DrG cell line and zebrafish larvae.