Synthesis, structures and properties of two-dimensional honeycomb and stepwise networks from self-assembly of tripodal ligand 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene with metal salts

Abstract

Three new coordination networks, [Zn(L)₂](ClO₄)₂ (1), [Mn(L)₂](SO₄)·16H₂O (2) and [Cd₃(L)₂(SO₄)₄(H₂O)₂(CH₃CH₂OH)₂][Cd(H₂O)₆]·2H₂O (3) were obtained by self-assembly of the corresponding metal salts with 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (L). Single crystal X-ray diffraction studies reveal that 1 and 2 have 2D honeycomb network structures in which each L ligand coordinates to three metal centers with the nitrogen atoms of imidazole group. When the ligand L reacts with CdSO₄·2.7H₂O, an interesting complex 3 with an unusual 2D stepwise structure involving the coordination of ethanol, water molecules, and sulfate anion, was obtained. Three distinct Cd centers reside in the complex 3. One of them binds to six water molecules to form a [Cd(H₂O)₆]²⁺ cation, and the other two are bridged by both L ligand and sulfate anion to give a 2D network. Furthermore, the complex 2 was found to have interesting properties of anion exchange and luminescence.