Structural diversity of terpyridine-based metal complexes with varied dicarboxylate auxiliary ligands

Abstract

Six new metal complexes, [Zn2L2(1,2-bdc)2] (1), [CuZnL2(1,2-bdc)2] (2), {[Cu2L(1,3-bdc)2]·2H2O}n (3), {[Cu2L2(1,4-bdc)](NO3)2·2H2O}n (4), [Cu2L2(1,4-bdc)(SCN)2]·2H2O (5) and {[ZnL(dc)]·H2O}n (6), have been synthesized by the reactions of 4′-4-(1,2,4-triazol-1-yl)-phenyl-2,2′:6′,2″-terpyridine (L) and different dicarboxylate auxiliary ligands with the corresponding metal salt. Complexes 1 and 2, with 1,2-benzenedicarboxylate (1,2-bdc2−), have dinuclear molecular structures. Complex 3, with 1,3-benzenedicarboxylate (1,3-bdc2−), is a (3,3,4)-connected three-dimensional (3D) framework with a Point (Schläfli) symbol of (4.6.8)(4.6.8)(6.84.10), while 4, with 1,4-benzenedicarboxylate (1,4-bdc2−), has an infinite chain structure, and further addition of SCN− anions to 4 results in the formation of the dinuclear complex 5. When 1,4-benzenediacrylic acid (H2dc) was employed as auxiliary ligand, complex 6 was obtained, having an infinite zigzag chain structure. All the complexes were characterized by elemental analyses, IR and X-ray crystallography. The results showed that the nature of the auxiliary ligand has a great impact on the structure of the complexes. Furthermore, the photoluminescence of the Zn(II) complexes and the reversible anion exchange property of 4 were investigated.