A series of 2D and 3D metal–organic frameworks based on different polycarboxylate anions and a flexible 2,2′-bis(1H-imidazolyl)ether ligand

Abstract

Eight new coordination polymers, namely [Ni(L1)(BIE)] (1), [Cu(L1)(BIE)] (2), [Cu(L2)(BIE)] (3), [Co(L3)(BIE)] (4), [Cu(L4)_0.5(BIE)] (5), [Co₂(L4)(BIE)₂]·H₂O (6), [Cu₅(L5)₄(μ₃-O)₂(BIE)₂(H₂O)₂] (7) and [Cu₃(L6)₂(BIE)₂(H₂O)₃] (8), where L1 = p-phthalate, L2 = o-phthalate, L3 = oxalate, L4 = 1,2,4,5-benzenetetracarboxylate, L5 = m-phthalate, L6 = 1,3,5-benzenetricarboxylate and BIE = 2,2′-bis(1H-imidazolyl)ether, were successfully synthesized under hydrothermal conditions. Polymers1–4 display 2D layer structures. 1, 2 and 3 hold the similar 4-connected 4⁴-sql nets, while 4 exhibits a 3-connected 6³-hcb net. 5 possesses an unusual 4-connected Kagomé net with two kinds of connected nodes. 6 shows a rare 3,4-connected (8³)₂(8⁵·10) topology with 3-connected nodes and square-planar 4-connected nodes. 7 exhibits an α-Po topology based on pentanuclear Cu(II) cluster. 8 is a unique self-penetrating 2D network with 3,4-connected (6·7²)(6·7·8)(6²·7·8²·9) topology. The structural differences of 1–8 suggest the importance of polycarboxylate ligands and central metals in the network construction of the coordination polymers.