A novel chiral Cd(II) coordination polymer based on achiral unsymmetrical 3-amino-1,2,4-triazole with an unprecedented μ₄-bridging mode

A novel chiral cadmium coordination polymer, Cd(AmTAZ)Cl (AmTAZH = 3-amino-1,2,4-triazole), has been solvothermally synthesized and structurally characterized by IR, elemental analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. This compound crystallizes in the chiral space group P2₁2₁2₁ with a = 6.4126(5), b = 7.8307(9), c = 10.4658(10) Å, V = 525.54(9) ų, and Z = 4. Interestingly, the amino group of the AmTAZ ligand is also coordinated to a cadmium ion besides three other N atoms of the triazolate ring, which "locks" the asymmetry of the AmTAZ and may transfer this asymmetry throughout the crystal structure to "direct" the formation of a chiral network. The structure possesses a unique three-dimensional open-framework and contains two different types of helical channels with left- and right-handed character presented alternately along the c-axis. The compound exhibits second-order nonlinear optical (NLO) activity, intense blue fluorescent emission, and high thermal stability.