Structural Versatility of Eight Zinc(II) Coordination Polymers Constructed with a Long Flexible Ligand 1,4-Bis(1,2,4-triazol-1-yl)butane

Abstract

The reaction of 1,4-bis(1,2,4-triazol-1-yl)butane (btb) with Zn(II) salts yields four coordination polymers from a one-dimensional (1D) zigzag chain [Zn(btb)(H2O)3(SO4)]n (1), undulated two-dimensional (2D) (4,4) network {[Zn(btb)2(H2O)2](NO3)2·2H2O}n (2), to a 3-fold interpenetrating three-dimensional (3D) α-polonium cubic network {[Zn(btb)3](BF4)2}n (3) and {[Zn(btb)3](ClO4)2}n (4). 1 further constructs a novel 3-fold interpenetrating 3D hydrogen bonding network. Four coordination polymers {[Zn(btb)(bdc)]·5H2O}n (5), {[Zn(btb)(H2O)4][Zn(btb)(btc)]2·4H2O}n (6), {[Zn2(btb)(btec)(H2O)2]·2H2O}n (7), and {[Zn(btb)2(H2O)2](H4btec)·(H2btec)·2H2O}n (8) were obtained with btb and 1,4-benzenedicarboxylate (bdc), 1,3,5-benzenetricarboxylate (btc), and 1,2,4,5-benzenetetracarboxylate (btec). 5 is a 2D (6,3) network with six Zn(II) atoms at six corners and four bdc and two double btb at six edges. In 6, btb and btc link two kinds of Zn(II) atoms to form an undulated 2D network. Each 2D network polycatenates two other identical networks, thus giving a rare (2D → 3D) parallel polycatenation network. 7 is a (3,4)-connected pillared-layer 3D porous network where [Zn2(btec)]n 2D layers are interlinked by btb pillars. 8 is comprised of [Zn(btb)2(H2O)2]n2n+ cationic chains, H2btec2− anions, neutral H4btec, and lattice water molecules. A novel 3D hydrogen bonding network of 8 is further constructed. The btb ligands adopt three conformations, namely, the completely anti (anti-anti-anti) conformation in 1 and 4, the anti-anti-gauche conformation in 2, 5, 6, and 8, and the gauche-anti-gauche conformation in 3, 4, and 7. Furthermore, thermal stability and luminescent properties were investigated.