Qing-Feng Yang

New Zn2+ coordination polymers with mixed triazolate/tetrazolate and acylhydrazidate as linkers

Under hydrothermal conditions, at different pH levels adjusted by H2ox (ox = oxalate, C2O42−) or N2H4, the reactions of Zn(CH3COO)2·2H2O, phthalic/3-nitrophthalic acid, N2H4·H2O and triazole/tetrazole afforded four new Zn2+ coordination polymers as [Zn5(OH)2(Hpth)2(pth)2(trz)2] (pth = phthalhydrazidate, trz = 1,2,4-triazolate) 1, [Zn3(OH)2(Hpth)2(datrz)2] (datrz = 3,5-diamino-1,2,4-triazolate) 2, [Zn2(pth)(atez)2] (atez = 5-aminotetrazolate) 3 and [Zn5(OH)2(ox)(apth)2(datrz)2] (apth = 3-aminophthalhydrazidate) 4. The acylhydrazide molecules H2pth and H2apth in compounds 1–4 originated from the hydrothermal in situ acylation of N2H4 with phthalic/3-nitrophthalic acid. When preparing compound 4, the reduction of –NO2 into –NH2 also occurred besides the acylation, creating finally a new acylhydrazide molecule H2apth. The X-ray single-crystal diffraction analysis revealed that (i) in compounds 1, 3 and 4, Zn2+ and pth/apth aggregate into the 1D endless chains. The triazolate/tetrazolate molecules extend the Zn2+-pth/apth chains into the different layer networks of compounds 1 and 4, and a 3D network of compound 3; (ii) in compound 2, the datrz molecules link the Zn2+ ions into a 2D layer network. Pth acts as the ancillary ligand; (iii) ox from H2ox was introduced into the final framework of compound 4; (iv) the acylhydrazide molecules exhibit three types of existing forms in compounds 1–4: the diketo form, the keto-hydroxyl form, and the dihydroxyl form. Of those, the dihydroxyl form was observed for the first time. The solid-state photoluminescence analysis indicated that only compound 4 emits green light, and the others do not emit light.

New Thiocyanatocadmate and Halo-thiocyanatocadmates Modified by Imidazole or Triazole Derivatives: Synthesis, Structural Characterization, and Photoluminescence Property

Abstract At pH 2, the simple room-temperature self-assemblies between Cd2+ salts, SCN− and organic bases created one new thiocyanatocadmate as [H2(L1)][Cd2(SCN)6] (L1 = 1,4-bis(2-methyl-1H-imidazol-1-ylmethyl)benzene) 1, and two new halo-thiocyanatocadmates as [H2(L2)][CdI2(SCN)2]·H2O (L2 = 3,5-bis (4-pyridyl)-1,2,4-triazole) 2, and [CdCl(SCN)(L3)] (L3 = 3-pyrazinyl-1,2,4-triazole) 3. X-ray single-crystal diffraction analysis reveals that (a) in 1, with H2(L1)2+ as the countercation, the SCN− groups tri-bridge the Cd2+ centers into a 1-D chained thiocyanatocadmate; (b) 2 is only a mononuclear iodo-thiocyanatocadmate, and H2(L2)2+ acts as the countercation. But via the π···π and Npyridyl–H···NSCN interactions, H2(L2)2+ and CdI2(SCN)22− aggregate together to form a 1-D supramolecular tube. Amongst the tubes, a chained water cluster with a zig-zag shape is observed; (c) 3 is an organically extended chloro-thiocyanatocadmate. Note that the report on this type of material is rather rare. It possesses a 3-D network structure with a dia topology, in which a castellated CdCl+ single chain is observed. L3 and Cl− act as a mixed bridge, whereas SCN− just serves as a terminal ligand in 3. The photoluminescence analysis indicates that the title compounds 1–3 all emit light (green light for 1, blue light for 2 and 3), which should be attributed to the ligand-centered electronic excitations.