Supramolecular assembly of a 4-(1-naphthylvinyl)pyridine-appended Zn(ii) coordination compound for the turn-on fluorescence sensing of trivalent metal ions (Fe3+, Al3+, and Cr3+) and cell imaging application

Abstract

Supramolecular systems are formed by the assembly of two or more molecules to achieve different or better functions with respect to those of the individual molecules. Secondary interactions contribute to the geometry and crystal structure of molecules, and it has been found that in supramolecular systems, the H⋯S interaction plays a pivotal role in molecular organization and properties. Moreover, depending on their arrangement, supramolecular assemblies help to recognize selected tri-positive metal ions. Herein, a 4-(1-naphthylvinyl)pyridine (4-nvp)-appended coordination compound, [Zn(4-nvp)₂(SCN)₂] (1), was synthesized and characterized by X-ray crystal structure determination. The solid-state structure of compound 1 reveals the formation of a 2D supramolecular architecture via C–S⋯H and C–H⋯π interactions. The compound is weakly emissive in CH₃CN/H₂O (1 : 1, v/v) and shows selective turn-on fluorescence enhancement in response to trivalent metal ions M³⁺ (M = Fe, Al, and Cr) over mono- and di-valent metal ions. Very low cytotoxicity and large improvement in the fluorescence intensity of the compound 1 upon the accumulation of tri-positive metal ions make the proposed probe suitable for the bio-imaging of M³⁺ (M = Al, Fe, and Cr) ions in living cells.