Seven structural versatile coordination polymers based on a flexible bis(triazole) and polycarboxylate co-ligands: syntheses, structures and properties

Abstract

Seven coordination polymers {[Mn(tmtz)0.5(OH-bdc)(H2O)2]·2.75H2O}n (1), [Mn(tmtz)1.5(1,3-bdc)]n (2), [Mn(tmtz)(1,4-bdc)]n (3), [Co(tmtz)(oba]n (4), {[Co4(tmtz)2(bptc)2(H2O)7]·3.5H2O}n (5), {[Ni(tmtz)1.5(1,3-bdc)]·0.5H2O}n (6), [Ni(tmtz)(oba)(H2O)]n (7) (tmtz = 1,4-bis(1,2,4-triazol-1-ylmethyl)-2,3,5,6-tetramethylbenzene, OH-bdc = 5-hydroxy-1,3-benzenedicarboxylate, 1,3-bdc = 1,3-benzenedicarboxylate, 1,4-bdc = 1,4-benzenedicarboxylate, H2oba = 4,4′-oxybis(benzoic acid), bptc = 3,3′,4,4′-benzophenonetetracarboxylate) have been synthesized and structurally characterized. 1 exhibits a 1D ladder structure and a 3D supramolecular architecture. 2 and 6 have similar 5-connected 2D networks through the 1,3-bdc ligand connecting [M(tmtz)1.5]n 1D ladders, with the point symbol (48·62). 3 has a (4,6)-connected 3D fsc network with a point symbol of (44·62)(44·610·8). 4 shows a 1D tubular-like chain. 5 exhibits a complicated (3,4,4)-connected 3D network with a point symbol of (4·10·12)2(4·83·10·12)2(82·102·122). Such a (3,4,4)-connected 3D network is unprecedented to the best of our knowledge. 7 displays a 2D (4,4) network which crystallizes in the chiral orthorhombic space group P212121. The results indicate that the central metal ions, polycarboxylate and flexible triazole co-ligands have a great effect on the formation and the structures of the coordination polymers. The thermal stability and luminescence were investigated. The crystal structures and solid-state circular dichroism (CD) spectra measurements confirmed the occurrence of the spontaneous resolution of 7 and demonstrated that the resulting crystal of 7 is a racemic mixture.