Syntheses and structures of three macrocyclic supramolecular complexes and one ZnII-containing coordination polymer generated from a semi-rigid multidentate N-containing ligand

Abstract

Semirigid organic ligands can adopt different conformations to construct coordination polymers with more diverse structures when compared to those constructed from rigid ligands. A new asymmetric semirigid organic ligand, 4-{2-[(pyridin-3-yl)methyl]-2H-tetrazol-5-yl}pyridine (L), has been prepared and used to synthesize three bimetallic macrocyclic complexes and one coordination polymer, namely, bis(μ-4-{2-[(pyridin-3-yl)methyl]-2H-tetrazol-5-yl}pyridine)bis[dichloridozinc(II)] dichloromethane disolvate, [Zn2Cl4(C12H10N6)2]·2CH2Cl2, (I), the analogous chloroform monosolvate, [Zn2Cl4(C12H10N6)2]·CHCl3, (II), bis(μ-4-{2-[(pyridin-3-yl)methyl]-2H-tetrazol-5-yl}pyridine)bis[diiodidozinc(II)] dichloromethane disolvate, [Zn2I4(C12H10N6)2]·2CH2Cl2, (III), and catena-poly[[[diiodidozinc(II)]-μ-4-{2-[(pyridin-3-yl)methyl]-2H-tetrazol-5-yl}pyridine] chloroform monosolvate], {[ZnI2(C12H10N6)]·CHCl3} n , (IV), by solution reaction with ZnX 2 (X = Cl and I) in a CH2Cl2/CH3OH or CHCl3/CH3OH mixed solvent system at room temperature. Complex (I) is isomorphic with complex (III) and has a bimetallic ring possessing similar coordination environments for both of the ZnII cations. Although complex (II) also contains a bimetallic ring, the two ZnII cations have different coordination environments. Under the influence of the I− anion and guest CHCl3 molecule, complex (IV) displays a significantly different structure with respect to complexes (I)–(III). C—H...Cl and C—H...N hydrogen bonds, and π–π stacking or C—Cl...π interactions exist in complexes (I)–(IV), and these weak interactions play an important role in the three-dimensional structures of (I)–(IV) in the solid state. In addition, the fluorescence properties of L and complexes (I)–(IV) were investigated.