Experimental and theoretical studies on a salamo-derived biscompartmental ligand and its rare tetranuclear Zn(II) complexes containing solvent effect

Abstract

Two rare multinuclear zinc(II) complexes: [Zn4(L)2(H2O)2]·4EtOH (1) and [Zn4(L)2(MeOH)2] (2) were self-assembled by the salamo-derived biscompartmental ligand H4L and Zn(NO3)2·6H2O in different mixed solvents. Complex 1 contains two fully deprotonated (L)4− parts, four zinc(II) atoms, and two coordinating water molecules. The Zn1 center is located in a slightly distorted triangular bipyramidal N2O3 coordination environment, and Zn2 is in a twisted tetragonal cone geometrical configuration. Complex 2 is composed of two fully deprotonated (L)4− parts, four zinc(II) ions, and two coordinating methanol solvent molecules. The different structures of the obtained complexes may be attributed to the different solvent effects used during the synthesis. Finally, the properties of the ligand H4L and its Zn(II) complexes were investigated, including molecular electrostatic potential surfaces (MEPs), Hirshfeld surfaces and interaction region indicator (IRI) analyses. Through these studies, the reactive active sites were visualised, the intermolecular interactions of the Zn(II) complexes were elucidated, which is consistent with the crystal structures of the Zn(II) complexes obtained . Their fluorescence properties were also explored.