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.