Syntheses, structures and properties of 5-azotetrazolyl salicylic acid and its dilanthanide complexes

Abstract

Two hydrated 5-azotetrazolyl salicylic acid (H₃ASA) of [(H₃ASA)·H₂O] (1) and [(H₃ASA)·4H₂O] (2) and five H₃ASA based dinuclear Ln³⁺ complexes of {[Ln₂(H_1.5ASA)₄(H₂O)₈]·6H₂O} [Ln = Dy (3), Tb(4)], {[Gd₂(H_1.5ASA)₄ (H₂O)₈]·5H₂O} (5), {[Sm₂(H_1.5ASA)₄(H₂O)₈]·6H₂O} (6) and {[Eu₄(H_1.5ASA)₈(H₂O)₁₈]·10H₂O} (7) have been synthesized and characterized by single crystal X-ray diffraction analysis. In 1 and 2, the neutral H₃ASA molecules show a trans-enol-E isomer but display two different dihedral angles. Complexes 3–7 exhibit three types of dinuclear structures in which the anionic ligands show two trans-enol-E/Z isomers. The photochromic and photoluminescent properties of 1, 3–7 and the magnetic properties for 3–7 were investigated.