Three Cd(II) complexes based on pyridine containing mercapto-triazole and aromatic multi-carboxylates: Syntheses, structures and luminescent properties

Three new Cd(II) complexes, [Cd2(2-aptt)2(L1)(H2O)]n (1), {[Cd3(2-aptt)2(L2)2]·4H2O}n (2) and {[Cd3(2-aptt)2(L3)]·2H2O}n (3) [2-apttH = 4-amino-3-(2-pyridyl)-1H-1,2,4-triazoleq-5-thione, H2L1 = terephthalic acid, H2L2 = isophthalic acid, H4L3 = pyromellitic acid], have been synthesized under the same reaction condition but tuned by different aromatic multi-carboxylates. The X-ray single crystal diffraction analysis reveals that complexes 1–3 all display 2D architectures with different features depending on the spatial arrangements of coordinated ligands as well as their unlike coordination modes. The 2D architecture of 1 constructs from Cd(II)–aptt– layer structure and "wave-like" Cd(II)–L12– chains. Cd(II)–aptt– chains and Cd(II)–L22– chains connect each other to generate the 2D grid structure of 2. “Butterfly-like” Cd(II)–2-aptt– chains are distributed under or on the surface formed by Cd(II) and L34− anions, giving rise to the 2D framework of 3. Moreover, the thermal stabilities of complexes 1–3 were investigated. The luminescent properties of complexes 1–3 and the free ligand were also studied.