Syntheses, Structures, and Characterization of a Series of Novel Zinc(II) and Cadmium(II) Compounds Based on 2,6-Di-(1,2,4-triazole-4-yl)pyridine

Using a pyridine-based bi-triazole ligand 2,6-di-(1,2,4-triazole-4-yl)pyridine (L), we have synthesized four novel
Zn(II)/Cd(II) coordination polymers, namely, {[Zn3L4(NCS)6]·2CH3OH·H2O}n (1), [CdL2(NCS)2]n (2), [CdL2(NO3)2]n (3), and
{[CdL(μ-ox)(H2O)]·2H2O}n (4) (ox = oxalate anion). 1 is the first triazole−zinc(II) compound simultaneously comprising four-
and six-coordinate zinc(II) centers. Weak C−H···N and C−H···S interactions assembled 1D chains of 1 into a 3D supramolecular
network, in which 1D hydrophilic channels encapsulating guest water and methanol molecules can be found. 2 contains a 1D double-stranded chain using CdL2(NCS)2 as repeating unit. 3 is a 2D polymer with chiral group P212121, indicating achiral ligand L and
metal centers can be used as building blocks to construct chiral crystals. For 4, Cd(II) centers are linked via a bis(bidentate) oxalate
anion to form 1D zigzag chains; furthermore, lattice water molecules act as hydrogen-bonding nodes to extend 4 into a 2D layer
structure through strong O···O hydrogen synthons. Intensive solid-state fluorescence spectra of 1−4 have been determined.