Syntheses and Characterization of Six Coordination Polymers of Zinc(II) and Cobalt(II) with 1,3,5-Benzenetricarboxylate Anion and Bis(imidazole) Ligands

Six new coordination polymers, namely [Zn1.5(BTC)(L1)(H2O)2]·1.5H2O (1), [Zn3(BTC)2(L2)3] (2), [Zn3(BTC)2(L3)1.5(H2O)]·H2O (3), [Co6(BTC)4(L1)6(H2O)3]·9H2O (4), [Co1.5(BTC)(L2)1.5]·0.25H2O (5), and [Co4(BTC)2(L3)2(OH)2(H2O)]·4.5H2O (6), where L1 = 1,2-bis(imidazol-1-ylmethyl)benzene, L2 = 1,3-bis(imidazol-1-ylmethyl)benzene, L3 = 1,1‘-(1,4-butanediyl)bis(imidazole), and BTC = 1,3,5-benzenetricarboxylate anion, were synthesized under hydrothermal
conditions. In 1−6, each of L1−L3 serves as a bidentate bridging ligand. In 1, BTC anions act as tridentate ligands,
and compound 1 shows a 2D polymeric structure which consists of 2-fold interpenetrating (6, 3) networks. In
compound 2, BTC anions coordinate to zinc cations as tridentate ligands to form a net with (64·82)2(86)(62·8)2
topology. In compound 3, BTC anions act as tetradentate ligands and coordinate to zinc cations to form a net with
(4·62·83)2(8·102)(4·6·83·10)2 topology. In compound 5, each BTC anion coordinates to three Co cations, and the
framework of 5 can be simplified as (64·82)2(62·82·102)(63)2 topology. For 4 and 6, the 2D cobalt−BTC layers are
linked by bis(imidazole) ligands to form 3D frameworks. In 6, the Co centers are connected by μ3-OH and carboxylate
O atoms to form two kinds of cobalt−oxygen clusters. Thermogravimetric analyses (TGA) for these compounds are
discussed. The luminescent properties for 1−3 and magnetic properties for 4−6 are also discussed in detail.