Synthesis,structure and photoluminescence of three 2D Cd(II) coordination polymers based on varied dicarboxylate ligand

Three coordination polymers (CPs) based on different dicarboxylic acids and Cd(II), [Cd₃(tpa)₃(DMA)₄] (1), [Cd₂(thpa)₂(DMA)₂·DMA] (2), and [Cd₃(eba)₃(DMA)] (3) (H₂tpa = terephthalic acid, H₂thpa = thiophenedicarboxylic acid, H₂eba?=?(ethene-1,2-diyl)dibenzoic acid, DMA = N,N′-dimethylacetamide), were synthesized under solvothermal conditions. The CPs were characterized by elemental analysis (EA), single-crystal X-ray crystallography, powder X-ray diffraction, infrared spectroscopy (IR), and thermogravimetric analyses. X-ray crystallographic analysis shows that 1 and 3 exhibit a 2D six-connected hxl network based on hourglass-like [Cd₃(COO)₆] SBUs, whereas 2 displays a 2D 4⁴-sql network based on [Cd₄(COO)₈] SBUs. Thermal stabilities and photoluminescence behaviors of the CPs are also discussed.     

Architectural diversity of six coordination compounds based on (S)-(+)-mandelic acid and different N-donor auxiliary ligands: syntheses,structures, and luminescent properties

Six transition metal coordination compounds with H₂mand and different N-donor ligands, [Co(Hmand)₂(2,2′-bipy)]·H₂O (1), [Ni(Hmand)₂(2,2′-bipy)]·H₂O (2), [Ni(Hmand)₂(bpe)] (3), [Zn(Hmand)₂(2,4′-bipy)(H₂O)]·2H₂O (4), [Zn(Hmand)(bpe)(H₂O)]_n[(ClO₄)]_n·nH₂O (5), and [Zn(Hmand)(4,4′-bipy)(H₂O)]_n[(ClO₄)]_n (6), were synthesized under different conditions (H₂mand = (S)-(+)-mandelic acid, bpe = 1,2-di(4-pyridyl)ethane, 4,4′-bipy = 4,4′-bipyridine, 2,4′-bipy = 2,4′-bipyridine, 2,2′-bipy = 2,2′-bipyridine). Their structures were determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, infrared spectra, thermogravimetric analysis, powder X-ray diffraction, and circular dichroism. Compounds 1 and 2 are isostructural (0-D structures), which are extended to supramolecular 1-D chains by hydrogen bonding. Compound 3 exhibits 1-D straight chain structures, which are further linked via hydrogen bond interactions to generate a 3-D supramolecular architecture. Compound 4 displays a discrete molecular unit. Neighboring units are further linked by hydrogen bonds and π–π interactions to form a 3-D supramolecular architecture. Compound 5 displays a 2-D undulated network, further extended into a 3-D supramolecular architecture through hydrogen bond interactions. Compound 6 possesses a 2-D sheet structure. Auxiliary ligands and counteranions play an important role in the formation of final frameworks, and the hydrogen-bonding interactions and π–π stacking interactions contributed to the formation of the diverse supramolecular architectures. Compounds 1, 2, 4, 5, and 6 crystallize in chiral space groups, with the circular dichroism spectra exhibiting positive cotton effects. Furthermore, the luminescent properties of 4–6 have been examined in the solid state at room temperature, and the different crystal structures influence emission spectra significantly.     

Cd(II) MOFs based on cadmium/carboxylate units and 4,4′-bis(benzoimidazol-1-yl)bibenzene: syntheses,structures, and luminescence

Solvothermal reactions of CdCl₂·2.5H₂O with 4,4′-bis(benzoimidazol-1-yl)bibenzene (bimbb) and 1,4-benzenedicarboxylic acid (1,4-H₂bdc), 4,4′-biphenyldicarboxylic acid (4,4′-H₂bpdb), 5-methyl-1,3-benzenedicarboxylic acid (5-Me-1,3-H₂bdc), or 1,3,5-benzenetricarboxylic acid (H₃btc) afforded four 3-D metal–organic frameworks, {[Cd₂(1,4-bdc)₂(bimbb)₂]·H₂O}_n (1), {[Cd₂(4,4′-bpdb)₂(bimbb)(H₂O)₂]} _n (2), [Cd₂(5-Me-1,3-bdc)₂(bimbb)] _n (3), and {[Cd₃(btc)₂(bimbb)(H₂O)₂]·2H₂O} _n (4). Complexes 1–4 were characterized by elemental analysis, IR spectroscopy, powder X-ray powder diffraction, and single-crystal X-ray diffraction. 1 possesses a 3-D framework with 2-D undulated (8,4) layers which are further connected by bimbb pillars. 2 forms a 3-D pillared-layer framework constructed through 2-D undulated (4,4) layers and bimbb pillars. 3 has 1-D ribbons of [Cd₄(5-Me-1,3-bdc)₄] _n which are linked by bimbb to form a 3-D structure. 4 exhibits a 3-D pillared-bilayer framework consisting of (6,3) double-decker [Cd₉(btc)₆(μ-OH₂)₆] _n layers and bimbb pillars. The Schläfli symbols for the four frameworks are (4²·6³·8)(4²·6⁵·8³) (1), (4⁴·6⁶) (2), (4⁴·6²)(4⁶·6⁴) (3), and (6³)(6¹⁰) (4). The photoluminescent properties of 1–4 were also investigated.     

Synthesis,Structures, and Properties of Cadmium(II) and Nickel(II) Coordination Polymers Based on a 4,4′‐Biphenyl‐Containing Ligand and Aliphatic Carboxylic Acids

The coordination polymers [Cd₂(bbmb)₂(L₁)(HL₁)_0.5(H₂O)]_n ( 1 ), [Cd₂(bbmb)₂(L₂)₂(H₂O) · (H₂O)]_n ( 2 ), and [Ni(bbmb)₂(L₃)]_n ( 3 ), were synthesized by the hydrothermal reaction of 4,4′‐bis(benzimidazol‐1‐ylmethyl)biphenyl (bbmb) with Cd^II/Ni^II ions in the presence of three flexible aliphatic acids [tricarballylic acid (H₃L₁), succinate (H₂L₂), and adipate (H₂L₃)]. Complexes 1 – 3 were structurally characterized by elemental analysis, IR spectroscopy and single‐crystal and X‐ray powder diffraction analyses. Complex 1 presents a 3D 3‐nodal (3,4,4)‐connected net with 3 , 4 , 4T78 topology, 2 exhibits a 3D network with 6⁶‐ dia topology, whereas 3 is a chain structure and further extended by hydrogen bonding interactions to form a 2D supramolecular network. Structural diversity of these complexes indicates that these frameworks could be tuned by the conformation of bbmb ligand and the different coordination modes of the aliphatic carboxylate co‐ligands. The thermal and fluorescence properties, the catalytic activities of complexes 1 – 3 in a Fenton‐like process were investigated.     

Structural diversity of a series of urea-based coordination complexes: from water tapes,water-sulfate chains,to supramolecular structures

[Hg₂(L₁)₂I₄] (1), [Cd₂(L₁)₂I₄] (2), {[Cd(L₁)₂(SO₄)(H₂O)]·4H₂O}_n (3), {[Zn₂(L₂)₂(Cl)₄]·0.5H₂O} (4), {[Cu₂(L₂)₂(SO₄)₂(H₂O)₄]·2.5H₂O} (5), and {[Cd(L₂)₂(SO₄)(H₂O)]·3H₂O}_n (6), based on N–(3–picolyl)–N′–(3–pyridyl)urea (L₁) or N–(4–picolyl)–N′–(3–pyridyl)urea (L₂), have been synthesized and characterized by elemental analyses, IR spectra, single-crystal and powder X-ray diffraction, and thermogravimetric analyses. Complexes 1 and 2 are isomorphous and feature similar rectangular metal organic loops, which were further extended into 2-D supramolecular structures through hydrogen bonds. Complex 3 possesses a 2-D sql sheet, and the channels between the neighboring sheets are filled with lattice water molecules, which formed a 1-D water tape. Complex 4 also exhibits a rectangular metal organic loop and a 3-D supramolecular structure with the help of hydrogen bonding interactions. Complex 5 also possesses a metal organic loop, and the water molecules interacted with sulfates, constructing a 1-D water–sulfate tube. Complex 6 features a 1-D loop polymeric chain. Moreover, the solid state luminescences of 1–4 and 6 have been investigated.     

Pyridine effected tunable luminescence properties of a 1D cadmium(II) polymer with tetranuclear second building units

One novel 1D polymer, [Cd₂(m-BrPhHIDC)₂(4,4′-bipy)(H₂O)₂]_n (1) (m-BrPhH₃IDC = 2-(3-bromophenyl)-1H-imidazole-4,5-dicarboxylic acid; 4,4′-bipy = 4,4′-bipyridine), has been hydrothermally synthesised and characterised by single-crystal X-ray diffraction, elemental analysis, IR, powder X-ray diffraction (PXRD) and thermogravimetric analysis. Polymer 1 composed of tetranuclear square [Cd₂(m-BrPhHIDC)₂] second building units and 4,4′-bipy bridges shows the interesting tunable luminescence properties aroused by pyridine. A luminescence enhance mechanism has been proposed.     

A bi-chain CoII coordination framework bridged by water molecules: magnetic properties and photocatalytic behavior

A new coordination framework, [Co₂(L)₂(bpy)₂(H₂O)]_n (1) (H₂L = (4-phenyl)-2,6-bis(4-carboxyphenyl)pyridine and bpy = 2,2′-bipyridine), has been prepared and structurally characterized. Complex 1 shows an interesting bi-chain substructure bridged by coordinated water molecules, which is further extended into a three-dimensional (3-D) supramolecular structure by π–π stacking interactions. Moreover, the magnetic properties and photocatalytic activity for degradation of methyl orange have been investigated.     

四个Cd(Ⅱ)配位聚合物:辅助配体对晶体结构以及荧光性能的影响

采用溶剂热的方法,将配位模式丰富的多羧酸有机配体5-(2-硝基-4-羧基苯氧基)-间苯二甲酸(H3ncpoi)与Cd~(2+)离子以及不同的辅助配体原位组装而成4个新的配位聚合物晶体:[Cd(Hncpoi)(2,2′-bpy)(H2O)]n(1),{[Cd2(Hncpoi)2(bpyp)(H2O)4]·3H2O}n(2),{[Cd2(Hncpoi)2(azpy)(H2O)2]·2H2O}n(3),{[Cd2(Hncpoi)2(dpe)(H2O)2]·2H2O}n(4),其中H3ncpoi为5-(2-硝基-4-羧基苯氧基)-间苯二甲酸,2,2′-bpy为2,2′-联吡啶,bpyp为1,4-二-吡啶基-4-亚甲基-哌嗪,azpy为4,4′-偶氮吡啶,dpe为1,2-二-(4-吡啶基)乙烯。对4个配合物进行了X射线单晶衍射、粉末衍射,元素分析、热重、荧光光谱等表征。X射线单晶结构分析表明,配合物1,2具有一维链状结构,而配合物3,4则具有二维(4,4)格子层状结构,一维链和二维层之间通过分子间作用力连接成三维超分子结构。进一步研究表明,辅助配体的构型、配位方式等对晶体结构具有决定性作用。与此同时,对几个配合物的荧光光谱进行分析,发现不同的辅助配体对配合物的荧光性能有着显著的影响。     

Synthesis and characterization of Pb(II) compounds constructed from N-tosyl-L-glutamic acid

{[Pb(tsgluo)]?·?H₂O} _n (1), [Pb₂(tsgluo)₂(phen)₂] (2), and [Pb₂(tsgluo)₂(bipy)₂] (3) (H₂tsgluo?=?N-p-tolylsulfonyl-L-glutamate, phen?=?1,10-phenanthroline, bipy?=?2,2′-pyridine) have been synthesized in the absence or presence of phen or 2,2′-bipy and structurally characterized by elemental analysis, IR, and X-ray crystallography. Single-crystal X-ray analyses reveal that tsgluo exhibits two coordination modes to link lead ions. Complex 1 gives a 2-D layer structure while 2 and 3 exhibit monomolecular structures; 3 is further connected into a double-chain structure by hydrogen bonds. Phen and 2,2′-bipy are very important for the crystal structure. Fluorescence of the compounds is also discussed.     

4个Cd(Ⅱ)配位聚合物:辅助配体对晶体结构以及荧光性能的影响

采用溶剂热的方法,将配位模式丰富的多羧酸有机配体5-（2-硝基-4-羧基苯氧基）-间苯二甲酸（H₃ncpoi）与Cd²⁺离子以及不同的辅助配体原位组装而成4个新的配位聚合物晶体：[Cd（Hncpoi）（2,2''-bpy）（H₂O）]_n（1）,{[Cd₂（Hncpoi）₂（bpyp）（H₂O）₄]·3H₂O}_n（2）,{[Cd₂（Hncpoi）₂（azpy）（H₂O）₂]·2H₂O}_n（3）,{[Cd₂（Hncpoi）₂（dpe）（H₂O）₂]·2H₂O}_n（4）,其中H₃ncpoi为5-（2-硝基-4-羧基苯氧基）-间苯二甲酸,2,2''-bpy为2,2''-联吡啶,bpyp为1,4-二-吡啶基-4-亚甲基-哌嗪,azpy为4,4''-偶氮吡啶,dpe为1,2-二-（4-吡啶基）乙烯。对4个配合物进行了X射线单晶衍射、粉末衍射,元素分析、热重、荧光光谱等表征。X射线单晶结构分析表明,配合物1,2具有一维链状结构,而配合物3,4则具有二维（4,4）格子层状结构,一维链和二维层之间通过分子间作用力连接成三维超分子结构。进一步研究表明,辅助配体的构型、配位方式等对晶体结构具有决定性作用。与此同时,对几个配合物的荧光光谱进行分析,发现不同的辅助配体对配合物的荧光性能有着显著的影响。     

Five metal imidazole dicarboxylate-based compounds comprising M3(MIDC)2 entities (M = Zn2+, Co2+, Mn2+): syntheses,structures and properties

Five metal imidazole dicarboxylate-based compounds, {[Zn₃(MIDC)₂(4,4′-bipy)₃](4,4′-bipy)·8H₂O}_n (1), {[Co₃(MIDC)₂(4,4′-bipy)₃](4,4′-bipy)·6H₂O}_n (2), {[Co₃(MIDC)₂(py)₂(H₂O)₂]}_n (3), {[Mn₆(MIDC)₄(py)₅(H₂O)₄]}_n (4), and {[Mn₃(MIDC)₂(Phen)₃(H₂O)₂]}_n (5) (H₃MIDC = 2-methyl-1H-imidazole-4,5-dicarboxylic acid; 4,4′-bipy = 4,4′-bipyridine; py = pyridine; Phen = 1,10-phenanthroline), have been synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. We control the coordination modes of H₃MIDC via hydrazine and obtained a series of coordination compounds containing honeycomb-like [M₃(MIDC)₂]_n layers. We also investigated the effects of different neutral terminal or bridging ligands on [M₃(MIDC)₂]_n layers. Coplanar [M₃(MIDC)₂]_n layers and 4,4-bipy were used to construct 3-D frameworks of 1 and 2. Puckered [M₃(MIDC)₂]_n layers were found in 3–5; 4 is the first [M₃(L)₂]_n layer structure with two crests and troughs during each period (L = imidazole-4,5-dicarboxylic acid or its analog). Compound 5 is the first puckered [M₃(L)₂]_n layer structure decorated by chelating neutral ligands. Compound 1 exhibits weak blue photoluminescence in the solid state at room temperature. Variable-temperature magnetic susceptibility measurements of 2–5 indicate strong antiferromagnetic interactions.     

Tuning topological and dimensional versatility from 1D to 3D of Zn/Cd luminescent biphenyl-3,5-dicarboxylate coordination polymers by ancillary ligand

The present study reports application of biphenyl-3,5-dicarboxylic acid (H₂L) as a versatile building block for synthesis of d¹⁰ metal coordination polymers (CPs). Five Cd(II) and Zn(II)-containing CPs based on N,N-donor ancillary ligands, [Cd₂(μ₃-L)₂(μ₂-4,4′-tmbpy)(MeOH)]_∞ (1), [Cd(μ₂-L)(2,2′-bpy)(H₂O)]_∞·n(MeOH) (2), [Cd(μ₂-L)(dipt)]_∞ (3), [Cd(μ₃-L)(phen)]_∞·nH₂O (4), and [Zn(μ₂-L)(μ₂-4,4′-tmbpy)]_∞·nH₂O (5) {4,4′-tmbpy = 4,4′-trimethylenedipyridine, 2,2′-bpy = 2,2′-bipyridine, dipt = 2,9-dimethyl-1,10-phenanthroline, phen = 1,10-phenanthroline} have been prepared under solvothermal conditions. 1–5 have been characterized by single crystal X-ray diffraction, elemental analysis, infrared (IR) spectra, and powder X-ray diffraction (PXRD). Complex 1 exhibits a three-dimensional (3-D) framework with a rare fsc-3,4-I41/amd topology. Complexes 2–4 show one-dimensional (1-D) structures. Complex 5 features a two-dimensional (2-D) layer structure with a sql topology. The structural and topological diversity of 1–5 are mainly attributed to the effect of the N,N-donor ancillary ligand. Solid-state luminescent properties and thermal stabilities of the obtained products have been investigated.     

Solvothermal syntheses,crystal structures and properties of four polymers built by p-methoxyphenyl imidazole dicarboxylates

By employing 2-(4-methoxyphenyl)-1H-imidazole-4,5-dicarboxylic acid (p-MOPhH₃IDC) to react with Cd(II), Zn(II) and Sr(II) ions, four polymers, [Cd(p-MOPhHIDC)(2,2′-bipy)]_n (2,2′-bipy = 2,2′-bipyridine) (1), [Zn_0.5(p-MOPhH₂IDC)·H₂O]_n (2), {[Cd₄(p-MOPhHIDC)₄(C₂H₅OH)₂(H₂O)₂]·4C₂H₅OH·2H₂O}_n (3) and {[Sr₂(H₂MOPhIDC)₂(C₈H₄O₄)(H₂O)₆]·6H₂O}_n (4) have been solvothermally synthesised and structurally characterised by single-crystal X-ray diffraction. Polymer 1 is a chain with 2,2′-bipy appending in the same side. Polymer 2 is a 2D rhombus grid structure. The π?π interactions between the aromatic groups supply the additional stabilisation for the solid-state structures of 1 and 2. Polymer 3 shows a 3D framework bearing 1D open channels. Polymer 4 exhibits a 2D latticed plane. The thermal and photoluminescence properties of 1–4 have been investigated as well.     

Self-assembly and crystal structures of coordination polymers constructed by 4′-hydroxyisoflavone-3′-sulfonates with Cs(I) and Rb(I)

Four coordination polymers, [CsL1(H₂O)₂]·H₂O (1), [CsL2(H₂O)₂]·H₂O (2), [Rb₂(L2)₂(H₂O)₂]·2H₂O (3) and [RbL3(H₂O)] (4), were synthesized by Cs(I), Rb(I) and 4′-hydroxyisoflavone-3′-sulfonates L1–L3 [L1 = 7-methoxy-4′-hydroxyisoflavone-3′-sulfonate, L2 = 7-ethoxy-4′-hydroxyisoflavone-3′-sulfonate, L3 = 7-ethoxy-4′,5-dihydroxyisoflavone-3′-sulfonate]. The crystal structures of 1–4 were determined by single-crystal X-ray diffraction. The influences of 4′-hydroxyisoflavone-3′-sulfonate ligands and Cs⁺, Rb⁺ on their structural features and self-assembly were investigated. The sulfonates of L1–L3 not only coordinate with Cs⁺ or Rb⁺ directly, but also bridge the organic region and the inorganic region in 1–4. Non-covalent interactions such as coordination interaction, π–π stacking interaction and hydrogen bonding assembled 1–4 into 3-D networks together with the electrostatic interactions between Cs⁺, Rb⁺ and the sulfonate anions.     

Syntheses,crystal structures and antibacterial activities of M(II) benzene-1,2,3-triyltris(oxy)triacetic acid complexes

Four metal(II) complexes with benzene-1,2,3-triyltris(oxy)triacetic acid (H₃L), {[Co_1.5(L)(H₂O)₆]·6H₂O}_n (1), {[Co_1.5(L)(4,4′-bipy)_1.5(H₂O)₄]·4H₂O}_n (2), {[Co(HL)(2,2′-bipy)(H₂O)₂]·1.5H₂O}_n (3), and {[Cu(HL)(phen)(H₂O)₂]·H₂O}_n (4) (4,4′-bipy = 4,4′-bipyridine; 2,2′-bipy = 2,2′-bipyridine; phen = phenanthroline), were prepared and structurally characterized. Complex 2 displays a 1-D structure, while 1, 3, and 4 reveal 0-D structures, which further extend to 3-D supramolecular networks by hydrogen bonding interactions, of which 1 and 4 contain double-helical chains, 2 includes meso-helices, and 3 comprises single-helices. Furthermore, the thermal stabilities and antibacterial activities of the complexes were studied.     

Structural and luminescent properties of a tetranuclear cage-type cadmium(II) carboxylate cluster containing a V-shaped water trimer

The structural characterization of tetranuclear cage-type cadmium(II) carboxylate [Cd₄(2-cpida)₂(2,2′-bpy)₆]·(2,2-bpy)·(ClO₄)·3H₂O (1) (2-H₃cpida = N-(2-carboxyphenyl)iminodiacetic acid, 2,2′-bpy = 2,2′-bipyridine) is described. H-bonding interactions between three lattice water molecules form a V-shaped trimer (H₂O)₃, which is stabilized by 1. In addition, luminescence investigations revealed that 1 shows enhanced emissions as compared with free 2-H₃cpida in the liquid state.     

Solvent-modulated zincII networks with different stacking arrangements

Two Zn^II complexes, [Zn₂(L)₂(DMF)(H₂O)₂]·DMF (1) and [Zn(L)(DEF)]·DEF (2), were synthesized by solvothermal reactions using 4,4′-(2,3,5,6-tetramethylbenzene1,4-diyl)dibenzoic acid (H₂L) and Zn(NO₃)₂·6H₂O in different solvents of DMF, ethanol, and water for 1 and N,N-diethylformamide (DEF) for 2. The L^2? with different coordination modes connect [Zn₂(COO)₂] secondary building units (SBUs) to generate a wavy 2-D (4,4) network of 1 while in 2 there are paddlewheel [Zn₂(COO)₄] SBUs which are connected by L^2? to form a planar 2-D (4,4) network. The 2-D layered structures show different stacking arrangements and are further linked by hydrogen bonding or C–H?π interactions to give 3-D architectures. The different structures and stacking arrangements of 1 and 2 result from different reaction solvents. Photoluminescence properties of the complexes were investigated.     

Two Cd(ΙΙ) complexes with xanthene-9-carboxylate ligand: syntheses,crystal structures,and emission properties

Two new Cd^II complexes, [Cd(L)₂(CH₃OH)₂]_∞ (1) and [Cd(L)₂(pyz)(H₂O)]_∞ (2), have been prepared by the reaction of xanthene-9-carboxylic acid (HL) and Cd(ClO₄)₂·6H₂O in the presence or absence of pyz co-ligand (L?=?xanthene-9-carboxylate and pyz?=?pyrazine). Their structures were determined by single-crystal X-ray diffraction. Complex 1 possesses a 1-D zigzag chain structure, whereas 2 has a 1-D linear chain that is further assembled into a 2-D network, and then an overall 3-D framework by inter-chain O–H?···?O hydrogen bonds and C–H?···?π supramolecular interactions. Both 1 and 2 are photoluminescent and their emission properties are closely related to their intrinsic structures.     

Four Zn(II)/Cd(II) coordination polymers derived from isomeric benzenedicarboxylates and 1,6-bis(triazol)hexane ligand: synthesis,crystal structure,and luminescent properties

Four coordination polymers, [Zn(o-bdc)(bth)_0.5(H₂O)] _n (1), [Cd(o-bdc)(bth)_0.5(H₂O)] _n (2), [Zn(m-bdc)(bth)] _n (3), and [Cd(p-bdc)(bth)?·?(H₂O)₂] _n (4) (where o-bdc?=?1,2-benzenedicarboxylate, m-bdc?=?1,3-benzenedicarboxylate, p-bdc?=?1,4-benzenedicarboxylate, and bth?=?1,6-bis(triazol)hexane), have been hydrothermally synthesized and structurally characterized. Both 1 and 2 are isostructural, featuring two binodal architectures: (6³)(6⁵·8) topology in terms of o-bdc and Zn^II/Cd^II as three- and four-connected nodes. Complex 3 shows a 2-D (4,4) network with the Zn?···?Zn?···?Zn angle of 57.84°, whereas 4 exhibits planar 2-D (4,4) network. These 2-D networks of 3 and 4 are extended by supramolecular interactions, such as CH?···?π/π–π stacking and hydrogen-bonding into 3-D architecture. A structural comparison of these complexes demonstrates that the dicarboxylate building blocks with different dispositions of the carboxyl site play a key role in governing the coordination motifs as well as 3-D supramolecular lattices. Solid-state properties such as photoluminescence and thermal stabilities of 1–4 have also been studied.     

Construction of three new metal-organic frameworks with distinct SBUs: trinuclear {Cd3(COO)6} clusters,inorganic -Cd-O-Cd- chains,and heterometallic trinuclear {Cd2Ba(COO)4} clusters

Three metal-organic frameworks (MOFs), [Cd₃(OABDC)₂(e-urea)₄]_n (1), [Cd₃(OABDC)₂(H₂O)₅)]_n (2) and [Cd₂Ba(OABDC)₂(H₂O)₇]_n (3) (H₃OABDC = 5-oxyacetate isophthalic acid, e-urea = 2-imidazolidinone), were prepared using H₃OABDC and metal salts. Single-crystal X-ray diffraction analyses reveal that 1 features a 2-D layered structure constructed from trinuclear {Cd₃(COO)₆} SBUs and represents a (3,6)-connected kgd topology. Compounds 2 and 3 are 3-D inorganic–organic hybrid frameworks; 2 employs infinite inorganic –Cd–O–Cd– chains as SBUs, whereas (3,6)-connected ant-type 3 employs heterometallic trinuclear {Cd₂Ba(COO)₄} clusters as SBUs. The structures of these three compounds indicate that the SBUs play an important role in the construction of MOFs. Moreover, the thermal stabilities and solid-state photoluminescent properties of these three compounds have also been investigated.