Syntheses,structures and photochromic properties of two tetrazolylazo-based K+ and Cd2+ complexes

A 5,5′-azotetrazole (H₂AT)-based K⁺ complex of [K₃(AT)_1.5(H₂O)₄] (1) and another 5-azotetrazolyl salicylic acid (H₃ASA)-based Cd²⁺ complex [Cd(H₂ASA)₂(H₂O)₂] (2) have been synthesized and characterized by single-crystal X-ray diffraction analysis. Complex 1 shows a 3-D structure formed by two μ_7- and μ_8-bridging trans-AT^2? ligands and μ_2-bridging waters linking three kinds of K⁺ ions. Complex 2 features a 1-D chain structure in which each trans-enol H₂ASA^? anion is a μ_2-bridging ligand with one N(tetrazole) atom and one O(carboxyl) coordinating to two different Cd²⁺ ions. The photochromic and photoluminescent properties for aqueous solutions of 1 and 2 were investigated.