Yan-Ning Wang

In situ synthesis and structural characterization of a series of acylhydrazidate-extended Ln3+ and Zn2+ coordination polymers

By utilizing the in situ hydrothermal acylation of N2H4 with aromatic polycarboxylic acids, a series of new acylhydrazidate-extended two-dimensional (2-D) or three-dimensional (3-D) coordination polymers, [Ln(epdh)3(H2O)] (Ln3+ = Dy3+1, Eu3+2, Tb3+3, Gd3+4, Y3+5, Lu3+6; epdh = 5-ethylpyridine-2,3-dicarboxylhydrazidate), [Dy(ox)(pdh)(H2O)] (ox = oxalate, pdh = pyridine-2,3-dicarboxylhydrazidate) 7, [Zn2(mpth)(atez)2] (mpth = 4-methylphthalhydrazidate, atez = 5-aminotetrazolate) 8 and [Zn3(OH)2(Hpth)2(atrz)2] (pth = phthalhydrazidate, atrz = 3-amino-1,2,4-triazolate) 9 were isolated. X-ray single-crystal diffraction revealed that (i) the isomorphic compounds 1–6 posses 2-D layer structures with (4,4) topologies. Two types of epdh molecules act as the rod-like connectors; (ii) compound 7 also possesses a 2-D layer structure, but shows a (6,3) topology. The pdh molecules first link the Dy3+ ions into a dimer. The ox molecules further extend the dimers into this 2-D layer network; (iii) compound 8 has a 3-D network structure (symbol: (4·64·8)2(42·62·82)), which is constructed from the one-dimensional (1-D) Zn2(mpth)2+ chains by the atez molecules; (iv) the 2-D layer network of compound 9 also shows a (6,3) topology, but the geometrical form is different from that of compound 7. Only the atrz molecule serves as the linker in compound 9; (v) via the N–H⋯O and/or N–H⋯N interactions, compounds 1–6, 7 and 9 self-assemble into the different 3-D supramolecular networks. Photoluminescence analysis revealed that (i) compounds 2 and 3 exhibit the characteristic transitions of the Eu3+ or Tb3+ ion; (ii) compounds 1, 4, 5 and 6 emit green light, suggesting their behaviors are dominated by the epdh molecules; (iii) compound 8 emits violet light, whereas compound 9 does not emit light.

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.

A new three-dimensional Zn2 + coordination polymer constructed from oxalate and 1,2,4-triazolate

A new 3-D Zn(2+) coordination polymer (CP) [(CH3)2NH2]3[Zn6(ox)4.5(trz)6]⋅4H2O (ox=oxalate; trz=1,2,4-triazolate) 1 was obtained by a simple solvothermal self-assembly. The crystal structural analysis demonstrates that the trz molecules link the Zn(2+) ions into a two-dimensional (2-D) layer network, which is based on the trinuclear Zn3(trz)6 clusters. The ox molecules serve as the linkers to propagate the 2-D layers into a three-dimensional (3-D) network of 1. The thermogravimetry (TG) behavior, photoluminescence property, and the sensing ability of 1 are investigated. The sensing experiment on nitrobenzene (NB) reveals that 1 can serve as a fluorescence probe to detect NB at the ppm concentration.