Syntheses, Structures, and Properties of a Series of Polyazaheteroaromatic Core-Based Zn(II) Coordination Polymers Together with Carboxylate Auxiliary Ligands
journal contributionposted on 06.01.2016, 00:00 by Shui-Sheng Chen, Liang-Quan Sheng, Yue Zhao, Zhao-Di Liu, Rui Qiao, Song Yang
Six Zn(II) coordination polymers, [Zn(H2L)(Hipa-CH3)2]·2H2O (1), [Zn2(HL)2(ipa-CH3)] (2), [Zn2(HL)2(ipa-NO2)]·2H2O (3), [Zn2(HL)2(ipa-NO2)] (4), [Zn2(HL)(BTCA)(H2O)]·H2O (5), and [Zn3(HL)3(BTCA)] (6), were synthesized by reactions of Zn(II) salts with rigid ligand 1-(1H-imidazol-4-yl)-4-(4H-tetrazol-5-yl)benzene (H2L) and different carboxylic acids, 5-methyl-isophthalic acid (H2ipa-CH3), 5-nitro-isophthalic acid (H2ipa-NO2), and 1,2,4-benzenetricarboxylic acid (H3BTCA). Complexes 1 and 2 were formed under different pH values, and 1 is a one-dimensional (1D) chain extended by hydrogen bonds and π–π stacking interactions to form a three-dimensional (3D) supramolecular polymer, while 2 exhibits a uninodal 6-connected 3D architecture with (412·63)-pcu topology based on the binuclear Zn(II) secondary building units (SBUs). Polymers 3 and 4 present a pair of pseudopolymorphs with layered-pillared framework. Polymer 3 possesses Zn2(HL–)22+ sheets pillared by the ipa-NO22– ligand to form a 3D net, while 4 builds on the [Zn2(HL)(ipa-NO2)]+ layer pillared by HL– ligand. Complex 5 is a (3,8)-connected tfz-d 3D net with point (Schläfli) symbol (43)2(46·618·84) based on the tetranuclear [Zn4(COO)4] SBUs, while the BTCA3– ligands act as three-connector pillars to link adjacent [Zn3(HL–)3]3– layers into a 3D net for 6. Complexes 1–6 exhibit intense light blue emission in the solid state at room temperature, and activated sample 6 shows highly selective CO2 uptake over N2 and H2.