Naphthoquinone based chemosensor 2-(2′-aminomethylpyridine)-3-chloro-1,4-naphthoquinone for metal ions: Single crystal X-ray structure, experimental and TD-DFT study

• Chemosensor 2-(2′-aminomethylpyridine)-3-chloro-1,4-naphthoquinone is presented.
• C⋯N, C⋯C and C–H⋯π interactions are observed.
• Deprotonated chemosensor can be used for several metal ions.
• Redox nature was evaluated by cyclic voltammetry study.
• Transition energies of neutral and anionic form of ligand was determined by TD-DFT.

Naphthoquinone based redox active chemosensor 1; 2-(2′-aminomethylpyridine)-3-chloro-1,4-naphthoquinone ligand has been synthesized and characterized. Chemosensor 1 crystallizes in monoclinic space group P21/n. Molecules showed intramolecular N–H⋯O and N–H⋯N, intermolecular N–H⋯O, C–H⋯O and slipped π–π stacking interactions. Chemosensor 1 showed orange colored solution in methanol and specifically detects Cu2+ ions by deprotonation of N–H. The deprotonation of amino N–H can also be achieved by mild base viz. triethylamine and chemosensor 1 can be used to detect several metal ions for example Ni2+, Mn2+ etc. that could observed by naked eye. Color changes observed were monitored by UV–visible and fluorescence spectra. Chemosensor 1 could provide either bidentate or tridentate coordination sites to metal ions. Redox nature of chemosensor 1 was evaluated by cyclic voltammetry studies. Electronic transition wavelengths of chemosensor 1 ligand have been evaluated in methanol, water and triethylamine by TD-DFT studies and comparative studies were performed with experimental results.

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