Jian-Kai Cheng

Synthesis, Structure, and Luminescent Properties of Hybrid Inorganic-Organic Framework Materials Formed by Lead Aromatic Carboxylates: Inorganic Connectivity Variation from 0D to 3D

The hydro(solvo)thermal reactions of Pb(OAc)(2).3H(2)O with the aromatic carboxylic ligands 1,3,5-benzenetricarboxylic and 1,4-, 1,2-, and 1,3-benzenedicarboxylic acids (1,3,5-H(3)BTC; 1,4-, 1,2-, and 1,3-H(2)BDC) have yielded a family of inorganic-organic framework materials: [Pb(2)(1,3,5-BTC)(mu(3)-OH)(H(2)O)](n) (Iota), [NaPb(1,3,5-BTC)(H(2)O)](n) (IotaIota), [Pb(1,4-BDC)](n) (IotaIotaIota), [Pb(5)(1,2-BDC)(4)(OAc)(2)](n) (IV), and {[Pb(5)(1,3-BDC)(5)(H(2)O)(2)](2).H(2)O}(n) (V). These complexes have been characterized by means of single-crystal X-ray diffraction, X-ray powder diffraction, thermogravimetric analysis-mass spectrometry, and photoluminescence spectra. They are all three-dimensional structures except for two-dimensional IV. Topology analysis reveals that complexes I an V represent rare (4,8)-connected flu and (3,4)-connected zeolite-like nets, respectively. The five complexes exhibit diverse inorganic connectivity, including a 0D Pb(4)O(16) cluster for I, a 1D Pb-O-Pb chain for II, a 2D Pb-O-Pb network for III and IV, and an unprecedented 3D Pb-O-Pb framework for V. And the diversity in inorganic arrays leads to differences in luminescent properties of these complexes.

Topology Analysis and Nonlinear-Optical-Active Properties of Luminescent Metal-Organic Framework Materials Based on Zinc/Lead Isophthalates

Two 3D Zn(II) and Pb(II) isophthalates, [Zn(ip)]n (1) and [Pb4(mu4-O)(ip)3(H2O)]n (2) (H2ip = isophthalic acid), have been prepared under hydro(solvo)thermal conditions and characterized by single-crystal X-ray diffraction. The two complexes crystallize in different space groups (P4(3)2(1)2 for 1 and P2(1)/c for 2) and have different bridging modes of the ip ligand. The 3D framework of 1 is constructed by the interconnection of ZnO4 polyhedra via ip ligands, which represents a chiral net with PtS-type topology. In contrast, complex 2 is formed by the combination of Pb4O-cluster secondary building units and has a novel (3.4.5)(3(2).4(5).5(6).6(7).7(2)) topology, which is the first ever example of a (3,7)-connected net. Complex 1 displays a second harmonic generation efficiency of about 1.5 times that of KH2PO4. Optical properties and thermal stabilities of the two complexes have been studied. Additionally, the calculations of band structure and density of states of 1 have also been performed with the density functional theory method.

Alkaline earth metal ion doped Zn(II)-terephthalates

Alkaline earth metal ion doped Zn(II)-terephthalates, [Zn2Mg(PBDC)3(DMA)2]n (1), [ZnCa(PBDC)2(DMA)2]n (2), [ZnSr(PBDC)2(DMA)2]n (3) and [Zn2Ba(PBDC)3(μ2-O1w)2(DMF)]n·n(DMF) (4) (H2PBDC = terephthalic acid, DMA = N,N′-dimethylacetamide, DMF = N,N′-dimethylformamide), have been solvothermally synthesized and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analyses, IR spectra, and thermal analyses. Different secondary building subunits, [Zn2Mg(μ2-COO)3] for 1, [ZnCa(μ2-COO)3] for 2, [ZnSr(μ2-COO)3] for 3, and [Zn2Ba(μ2-COO)4(μ2-O1w)2] for 4, are realized by the introduction of different alkaline earth ions. Compound 1 is a two-dimensional (2D) layer structure with 6-connected hxl topology. Compounds 2 and 3 are isostructural and exhibit a three-dimensional (3D) framework with (3,5)-connected {4.62}{4.66.83} topology owing to their similar secondary building subunits. Compound 4 is a three-dimensional (3D) opened framework with the channels occupied by the disordered lattice DMF molecules and can be simplified into a (3,8)-connected {42.6}2{44.614.78.82} topology. Moreover, the solid-state fluorescence of compounds 1–4 have also been investigated at room temperature.

Synthesis, Structure, and Physical Properties of a New Anions-Controlled Cd(II)-Guanazole (3,5-Diamino-1,2,4-triazole) Hybrid Family

Nine members of a new anions-controlled Cd(II)-guanazole (3,5-diamino-1,2,4-triazole=Hdatrz) hybrid family, that is, [Cd3(datrz)6(H2O)2] (1), [Cd3(datrz)4F2] (2), [Cd5(datrz)4Cl4(OH)2] (3), [Cd5(datrz)4Br4(OH)2] (4), [Cd3(datrz)2(SO3)2].(H2O) (5), [Cd3(datrz)2(O2CMe)4] (6), [Cd(datrz)(O2CEt)] (7), [Cd(Hdatrz)(O2CtBu)2] (8), and [Cd(Hdatrz)2(H2Edta)] (9) have been synthesized by exploiting hydrothermal reactions of guanazole with suitable cadmium salts under appropriate reaction conditions. With effective control of inorganic or organic anions, the coordination diversity of the guanazole ligand in 1-9 manifests an unprecedented enrichment with five bridging modes varying from bidentate to quadridentate, two of which are first reported. Compound 1 is the first reported three-dimensional chiral complex constructed from the guanazole ligand which adopts a novel N1, N2, amino N-bridging mode. Halogen anions F-, Cl-, and Br- controlled compounds 2-4 are all three-dimensional, with their guanazole ligands possessing another novel quadridentate bridging mode. Sulfite anions controlled compound 5 displays a three-dimensional network with peculiar cage-like hexnuclear cadmium clusters. As for organic anions, low dimensional structures have been found for alkylcarboxylate anions MeCO2-, EtCO2-, and tBuCO2- controlled compounds 6, 7, and 8 (two-dimensional) and for H2Edta2- controlled compound 9 (zero-dimensional), and their guanazole ligands manifest low coordination numbers as well. These hybrid materials also present interesting structure-induced physical properties. The chiral compound 1 exhibits the second-order nonlinear optical properties at room temperature. Compounds 2-9 except 6 all exhibit photoluminescence of blue fluorescent emissions in the solid state at ambient temperature, which may be assigned to the intraligand pi-pi* transitions. Some structure related red or blue emission shifts have been investigated. Thermal studies show that most compounds of this study possess a high thermal stability.

Role of molar-ratio, temperature and solvent on the Zn/Cd 1,2,4-triazolate system with novel topological architectures

Five members of the Zn/Cd triazolate family, [Zn(TAZ)(OAc)]n (1), [Zn4(TAZ)6(OAc)2]n (2), [Cd3Cl3(TAZ)3(DMF)2]n (3), [CdCl2(TAZ)]n·n(H2O) (4) and [Cd2Cl(μ4-AmTAZ)2(μ-AmTAZ)]n (5), have been synthesized from TAZ/AmTAZ and corresponding metal salts, where TAZ, AmTAZ and DMF are 1,2,4-triazole, 3-amino-1,2,4-triazole and N,N′-dimethylformamide, respectively. X-ray analysis shows that all compounds except 4 manifest interesting 3D frameworks with novel topologies. Compounds 1 and 2 are temperature-and-solvent controlled assemblies and possess 3D (3,4,6)-connected (3.72)2(32.4.73)(32.4.76.86) topology and 3D (3,6)-connected (4.82)3(83)(46.86.123) topology, respectively. However, compounds 3 and 4 are molar-ratio-dependent compounds. The framework of 3 is a 3D (3,4,5)-connected one with (4.102)(4.62)2(43.62.8)2(64.106) topology, in which the 1D channels are filled with coordinated DMF, while only a 1D chain-like motif is formed in 4. In addition, a 3D (4,6)-connected (3.42.52.6)2(32.42.54.65.72)(32.44.54.64.7) topology is observed in the framework of 5, where AmTAZ is used instead of TAZ in the syntheses of compounds 1–4. Solid state measurements reveal that all these coordination polymers are thermostable and luminescent under ambient conditions.

Scorpion-shaped carboxylate ligand tailored molecular square, bilayer, self-threading and (3,6)-connected nets

A novel designed scorpion-shaped 5-oxyacetateisophthalic acid (H3OABDC) was used to construct a series of luminescent metal–organic frameworks, namely [Zn2(HOABDC)2(phen)2(H2O)2]n·nH2O (1), [Zn2(OABDC)(4,4′-bipy)(μ2-OH)(H2O)]n·4/3nH2O (2), [Cd3(OABDC)2(4,4′-bipy)4(H2O)4]n·2nH2O (3), [Cd2(OABDC)(phen)2(μ3-OH)]n·1/3nH2O (4), and [Zn8(OABDC)4(2,2′-bipy)4(μ2-OH)4]n·2nH2O (5) (bipy = bipyridine, phen = 1,10-phenanthroline). Complex 1 features a discrete molecular square and π–π and C–H⋯π interactions between molecular squares give rise to a 2D sheet. Complex 2 shows an unusual 2D bilayer architecture with (3,5)-connected topology. A prominent structural feature in 3 is the self-threading 2D layered structure. Both 4 and 5 exhibit (3,6)-connected topology. In 4, an extraordinary folded four-step-ladder Cd4(OH)2 unit acts as 6-connected node and the framework is 2D (3,6)-connected net. While in 5, the Zn2(OH) unit adopts octahedral geometry and the whole framework features a 3D (3,6)-connected rutile (rtl) topology. Photoluminescence studies revealed that these complexes are interesting blue, green and orange luminescent materials. The thermal stabilities of these complexes are also discussed.

Unusual parallel entanglement of metal–organic 2D frameworks with coexistence of polyrotaxane, polycatenane and interdigitation

Three novel luminescent metal–organic frameworks [Zn(1,2-BBOMB)(4,4′-bipy)1/2]n (1), [Zn2(1,3-BBOMB)2(4,4′-bipy)]n (2) and [Zn4(1,2-BBOMB)4(bpp)2]n (3) have been synthesized by combining the conformationally flexible V-shaped long multicarboxylate ligands and the rigid 4,4′-bipy or flexible bpp ligands with zinc ions under hydrothermal conditions. It is worth mentioning that the layers observed in the three compounds can be reduced to the same 6-connected topological net with (22·48·65) symbol. These complexes display a structural evolution from a two-dimensional (2D) polyrotaxane and polycatenane framework to a three-dimensional (3D) architecture with coexistence of polyrotaxane, polycatenane and interdigitation. The three species contain loops and rods that are interlaced in a highly rare parallel fashion, but with twofold (2D → 2D), triply (2D → 2D) and triply (2D → 3D) entangled features in complexes 1, 2 and 3, respectively. Furthermore, the rotaxane-like interactions between the loops and the rods exhibit a progressive change from one loop interacting with a single rod, to one loop interacting with two identical rods, to finally one loop interacting with two conformationally different rods in complexes 1, 2 and 3, respectively. Photoluminescence studies revealed that these complexes are potential violet, blue and green luminescent materials. The thermal stabilities of these complexes were also discussed.

A rare metal–organic 3D architecture with a pseudo-primitive cubic topology with double edges constructed from a 12-connected SBU

The hydrothermal assembly of CdCl2 with isophthalatic acid (H2ip) and 1,3-bis(4-pyridyl)propane (bpp) yielded a novel 3D coordination polymeric complex, [Cd4(ip)4(bpp)2]n (1), which presents an interesting non-interpenetrated pseudo-primitive cubic (pcu) topology with double edges constructed from a 12-connected SBU.

A novel 3D framework generated by unusual pillared 2D bilayer motifs

A hydrothermally synthesized mixed-ligand molecular solid has been formulated. The X-ray diffraction analysis of a single crystal revealed a novel 3D architecture generated by unusual 2D bilayer motifs linked up by pillars. Three types of channels in one direction are established inside the structure.

A twisting chiral ‘dense’ 75.9 net, incorporating a helical sub-structure

A new twisting chiral dense 75.9 net, containing only planar four-coordinate nodes and incorporating single helical sub-structures with the same accessibility, was represented.