Syntheses,crystal structures,and catalytic activities of three new Cu(II) coordination polymers based on 2-(1H-1,2,4-triazole)-1-acetic acid

Three new coordination polymers, {[Cu(trza)(2,2′-bipy)(H₂O)]?·?(ClO₄)} _n (1), {[Cu(trza)(2,2′-bipy)(H₂O)]?·?(BF₄)} _n (2), and {[Cu(trza)(4,4′-bipy)]?·?(H₂O)?·?(ClO₄)} _n (3) (Htrza?=?2-(1H-1,2,4-triazole)-1-acetic acid), have been synthesized and characterized by single-crystal X-ray diffraction analysis. Both 1 and 2 exhibit 1-D chain structure while 3 displays 2-D layer structure. The catalytic activities of 1 and 3 in the green oxidative coupling of 2,6-dimethylphenol have been investigated.     

Syntheses,structures, and luminescence of coordination compounds based on N-containing polycarboxylates

Six coordination compounds constructed by two structurally related flexible nitrogen-containing polycarboxylate ligands 2,2′-(2,2′-(ethane-1,2-diylbis(oxy))bis(2,1-phenylene))bis(methylene)bis(azanediyl)dibenzoic acid (H₂L1) and 5,5′-(2,2′-(ethane-1,2-diylbis(oxy))bis(2,1-phenylene))bis(methylene)bis(azanediyl)diisophthalic acid (H₄L2) have been synthesized: [Ni(H₂O)₆]?·?L1?·?(C₂H₅OH)_0.5?·?H₂O (1), [Co(L1)(L3)]?·?CH₃OH (2), [Ni(L1)(L3)]?·?CH₃OH (3), [Zn(L1)(L3)]?·?CH₃OH (4), [Cd(L1)(L3)]?·?CH₃OH (5), and [Zn(L2)_0.5(phen)]?·?C₂H₅OH (6), where L3?=?3,4?:?9,10?:?17,18?:?23,24-tetrabenzo-1,12,15,26-tetraaza-5,8,19,22-tetraoxacyclooctacosan and phen?=?1,10-phenanthroline. The crystal structures have been determined by single-crystal X-ray diffraction. Compound 1 displays a discrete structure, which is further linked by hydrogen bonds to form a 2-D supramolecular layer. Compounds 2–5 display similar structures. These compounds possess 1-D meso-chain structures linked by L1 and metals. The C–H?···?π interactions from neighboring chains extend the chains in different directions, giving a 3-D plywood network. Compound 6 possesses 2-D layers, which are further linked by hydrogen-bonding interactions to generate a 3-D supramolecular architecture.     

Ferrocene-carboxylate coordination complexes bridged by different N-containing ligands

Six new coordination complexes, [Cd(η ²-OOCCH=(CH₃)CFc)₂(bix)]₂·(CH₃OH)_0.5 (1), [Zn(η ²-OOCCH=(CH₃)CFc)(η ¹-OOCCH=(CH₃)CFc)(bix)]₂·(H₂O)_0.5 (2), [Zn(η ²-OOCCH=(CH₃)CFc)₂(pbbm)]₂·(CH₃OH)₂ (3), {[Mn(η ¹-OOCCH=(CH₃)CFc)₂(bbbm)(H₂O)₂]·(CH₃OH)₃}_n (4), {[Cd(η ¹-OOCCH=(CH₃)CFc)₂(bbbm)]·(CH₃OH)₂}_n (5), and [Cd(η ²-OOCCH=(CH₃)CFc)₂(pmbbm)]_n (6) {Fc?=?(η ⁵-C₅H₄)Fe(η ⁵-C₅H₄), bix?=?1,4[bis(imidazol-1-ylmethyl)benzene], pbbm?=?1,1′-[(1,4-propanediyl)bis-1H-benzimidazole], bbbm?=?1,1′-[(1,4-butanediyl)bis-1H-benzimidazole)], pmbbm?=?1,1′-[(1,4-pentanediyl)bis-1H-benzimidazole]}, were prepared and characterized. X-ray crystallographic analysis reveals that 1–3 are dimers bridged by bix and pbbm. Complexes 4–6 are one-dimensional (1-D) structures bridged by bbbm and pmbbm, respectively. Various π–π interactions were discovered in 1–6 that make significant contributions to molecular self-assembly. Solution differential pulse voltammetry of 1–6 indicates that the half-wave potentials of the ferrocenyl moieties in these complexes shift to positive potential compared with that of 3-ferrocenyl-2-crotonic acid.     

Synthesis,crystal structures,and photoluminescence of two new zinc complexes based on 2,2′-thiodibenzoic acid

{[Zn₂(tdba)₂(phen)₂(H₂O)₂]?·?2H₂O?·?2DMF} _n (1) and [Zn(tdba)(bpy)] _n (2) (H₂tdba?=?2,2′-thiodibenzoic acid, phen?=?1,10-phenanthroline, bpy?=?2,2′-bipyridine, DMF?=?dimethylformamide) were hydrothermally synthesized, and characterized by single-crystal X-ray diffraction analysis, FT-IR, and elemental analysis. The obtained complexes exhibit different structures. Compound 1 is 0-D with tdba connecting two Zn ions in a μ ₁–η ¹/μ ₁–η ¹ coordination forming a dinuclear molecule. Each molecule is further connected with neighbors via hydrogen-bonding and π?···?π interactions. Compound 2 displays a 1-D structure in which Zn²⁺ centers are connected via tdba anions into 1-D chains propagating along the a-axis; these chains are further packed via π?···?π interactions. In addition, photoluminescence for 1 and 2 has been investigated.     

Supramolecular networks constructed by cationic copper(II) complexes incorporating hybrid water–anionic polymeric assemblies

Two complexes, [Cu₂(TFSA)(2,2′-bpy)₄]?·?TFSA?·?8H₂O (1) and {[Cu(4,4′-bpy)(H₂O)₂]?·?TFSA?·?6H₂O} _n (2) (H₂TFSA?=?tetrafluorosuccinic acid, 2,2′-bpy?=?2,2′-bipyridine, and 4,4′-bpy?=?4,4′-bipyridine), have been synthesized and structurally characterized by X-ray structural analyses. Complex 1 is a binuclear molecule bridged by TFSA ligands; 2 is a 1-D chain bridged by 4,4′-bpy ligands. The asymmetric units of the two complexes are composed of cationic complexes [Cu₂(TFSA)(2,2′-bpy)₄]²⁺ (1) and [Cu(4,4′-bpy)(H₂O)₂]²⁺ (2), free TFSA anion, and independent crystallization water molecules. A unique 2-D hybrid water–TFSA anionic layer by linkage of {[(H₂O)₈(TFSA)]^2?} _n fragments consisting of 1-D T6(0)A2 water tape and TFSA anionic units by hydrogen bonds in 1 was observed. Unique 2-D hybrid water–TFSA anionic layer generated by the linkage of {[(H₂O)₆(TFSA)]^2?} _n fragments consisting of cyclic water tetramers with appended water molecules and TFSA anionic units, and 1-D metal–water tape [Cu–H₂O?···?(H₂O)₆?···?H₂O^?] _n in 2 were found. 3-D supramolecular networks of the two complexes consist of cationic complexes and water–TFSA anionic assemblies connected by hydrogen bonds.     

Syntheses and structural characterizations of three transition metal coordination complexes based on flexible 2,4-dichlorophenoxyacetate (2,4-DCP)

Three transition metal coordination complexes, {[Co(2,4-DCP)₂(μ ₂-H₂O)(H₂O)₂]?·?(H₂O)₂} _n (1), [Zn(2,4-DCP)(IN)] _n (2), and [Mn₂(2,4-DCP)₃(DMPY)₂(μ ₂-H₂O)(H₂O)]?·?(2,4-DCP)?·?0.2(H₂O) (3) (2,4-DCP?=?2,4-dichlorophenoxyacetate, IN?=?isonicotinate, DMPY?=?5,5′-dimethyl-2,2′-bipyridine), have been prepared under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Complex 1 displays a 1-D chain through cobalt and bridging water molecules with Co?···?Co distance of 4.028(2)?Å. Complex 2 shows a 2-D (4,4) net, which is extended into a 3-D supramolecular framework by weak hydrogen-bonding interactions. Complex 3 consists of discrete dinuclear cations, 2,4-DCP counter ions and free water molecules, which are assembled into a packing structure through π?···?π stacking of inversion-related DMPY ligands and hydrogen bonds. Magnetic susceptibility measurements show weak antiferromagnetic interactions in 1. The photoluminescence and lifetime of 2 in the solid state have also been studied.     

Syntheses,crystal structures,and luminescence of two new coordination polymers based on biphenyl-2,2′,4,4′-tetracarboxylate

Two new coordination polymers, [Zn(H₂btc)(4,4′-bpy)₂] _n (1) and {[Cd(H₂btc) (terpy)]?·?H₂O} _n (2) (H₄btc?=?biphenyl-2,2′,4,4′-tetracarboxylic acid, 4,4′-bpy?=?4,4′-bipyridine, terpy?=?terpyridine), have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. Complexes 1 and 2 are 1-D chains linked through partially deprotonated H₄btc. The adjacent 1-D chains of 1 are further formed into 2-D supramolecular architecture through inter-chain N–H···O hydrogen bonds. In contrast, due to a different auxiliary ligand, the 1-D chains of 2 are further extended into 3-D supramolecular framework through inter-chain O–H···O hydrogen bonds. Thermal stabilities and luminescence of 1 and 2 were also studied.     

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.     

Four anthraquinone-1,5-disulfonate-based metal complexes incorporating N-heterocyclic coligands: synthesis,crystal structures,and fluorescence

Four new anthraquinone-1,5-disulfonate (L)-based metal complexes with N,N-bidentate chelating coligands, {[Pb(phen)₂(L)]?·?4H₂O} _n (1), {[Mn₂(2,2′-bipy)₂(H₂O)₆(L)]?·?L?·?6H₂O} (2), [Co(phen)₂(H₂O)(L)] (3), and [Zn(phen)₂(H₂O)(L)] (4) (phen = 1,10-phenanthroline and 2,2′-bipy?=?2,2′-bipyridine), have been hydrothermally synthesized and were structurally characterized by single-crystal X-ray diffraction, elemental analyses, FT-IR spectra, thermogravimetric curves, and solid luminescence spectra. Structural analysis suggests that 1 is a polymeric 1D zigzag chain bridged by dianionic L. In contrast, the other three complexes have discrete centrosymmetric binuclear structure for 2 and isolated isomorphic mononuclear entities for 3 and 4, which are further assembled into 3D supramolecular networks by abundant hydrogen-bonding and/or π–π stacking interactions. Additionally, 2 and 4 exhibit favorable luminescent emissions, suggesting they are potential candidates for light emission materials.     

Synthesis and crystal structure of two praseodymium 2-iodobenzoic acid complexes

Two new complexes, {[Pr(2-IBA)₃?·?2,2′-bipy]₂·[Pr(2-IBA)₃?·?2,2′-bipy]₂?·?0.5C₂H₅OH?·?H₂O} (1) and [Pr(2-IBA)₃?·?phen]₂ (2) (2-IBA?=?2-iodobenzoate; 2,2′-bipy?=?2,2′-bipyridine; phen?=?1,10-phenanthroline) were synthesized, and their crystal structures were determined by X-ray diffraction. Complex 1 consists of two binuclear molecules [Pr(2-IBA)₃?·?2,2′-bipy]₂ (a) and [Pr(2-IBA)₃?·?2,2′-bipy]₂ (b), half uncoordinated ethanol and one uncoordinated water. In the two molecules (a) and (b), the coordination environment of central ions is similar. The Pr1³⁺ ion in molecule (a) and Pr2³⁺ ion in molecule (b) are nine-coordinate with seven oxygen atoms from five 2-IBA ligands and two nitrogen atoms from one 2,2′-bipy molecule. The crystal structure of complex 2 is similar to that of binuclear [Pr(2-IBA)₃?·?2,2′-bipy]₂ in complex 1.     

N-donor co-ligand-driven zinc coordination polymers based upon a bithiophene dicarboxylate: syntheses,structures, and luminescent properties

Three zinc compounds assembled from a bithiophene dicarboxylic acid (H₂DMTDC) and different N-donor co-ligands, [Zn(DMTDC)(bpt)(H₂O)]_n (1), {[Zn(DMTDC)(5,5-dmbpy)]·0.5DMF·1.5H₂O}_n (2), and {[Zn(DMTDC)(1,3-bimb)]·2DMF·H₂O}_n (3) (H₂DMTDC?=?3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid, bpt?=?4-amino-3,5-bis(4-pyridyl)1,2,4-triazole, 5,5′-dmbpy?=?5,5′-dimethyl-2,2′-bipyridyl, 1,3-bimb?=?1,3-bis(imidazol-1ylmethyl)benzene), were solvothermally synthesized and characterized. Compounds 1 and 2 are 1-D linear and zigzag chains with different supramolecular structures. In 1, adjacent chains form zipper-like structures through N–H?N interactions. In 2, however, chains in adjacent layers are stacked in an unusual unparallel level through C–H?O interactions. Compound 3 features a highly corrugated 2-D (4,4) layer and the layers are penetrated by each other to give 3-D polycatenations. Right- and left-handed helical Zn-bimb chains are arranged alternately within and between the layers, leading to mesomeric property of the whole network. Thermal stability and the decomposed products of all compounds were investigated. Luminescent properties of the ligands and compounds in the solid state at room temperature have also been explored. Moreover, the luminescence intensities of the compounds in different solvents are largely dependent on the solvent.     

Syntheses,crystal structures,and characterization of three metal–organic complexes with 2,2′-biphenyldicarboxylic acid and phenanthroline ligands

Three complexes constructed with 2,2′-biphenyldicarboxylic acid, multidentate nitrogen donors, and metal salts, {[Cd(2,2′-dpdc)(tppp)(H₂O)]₂?·?2H₂O} _n (1), {[Pb(2,2′-dpdc)(pyphen)]₂} _n (2), and {[Pb(2,2′-dpdc)(dppz)]} _n (3) (H₂dpdc = 2,2′-diphenyldicarboxylic acid; tppp = 4-(1H-1,3,7,8-tetraazacyclopenta[l]phenanthren-2-yl)phenol; pyphen?=?pyrazino[2,3-f]-[1,10]phenanthroline; and dppz = dipyrido[3,2-a:2′,3′-c]phenazine), are synthesized under hydrothermal conditions. These complexes are characterized by single-crystal X-ray diffraction, elemental analysis, IR, TGA, and photoluminescence. In 1, two 2,2′-dpdc ions bridge two Cd(II) ions to form an isolated cluster with Cd?···?Cd distance of 5.023(4)?Å. These clusters are further linked by intermolecular hydrogen bonds, yielding a 2-D supramolecular structure. Complex 2 contains two crystallographically independent Pb(II) ions in the asymmetric unit. Pb1 ions are bridged by 2,2′-dpdc anions to form a chain along the x-axis. Two Pb2 ions are coordinated by two 2,2′-dpdc anions and two pyphen ligands to form a cluster. These clusters are linked by π–π interactions to yield a 1-D supramolecular chain along the y-axis. In 3, neighboring Pb(II) atoms are bridged by 2,2′-dpdc anions to form a 1-D chain structure. Further, the chains are linked into a 3-D supramolecular network through aromatic π–π interactions.     

Complexes based on ferrocenecarboxylate ligands: steric hindrance induced by ferrocenyl groups

Three metal complexes with ferrocenecarboxylate ligands, [M₂(η ²-FcCOO)₂(μ₂-η ²-FcCONHCH₂COO)₂(phen)₂]?·?nH₂O [M?=?Pb, n?=?6 (1) and M?=?Cd, n?=?2 (2)] and [Cd(FcCONHCH₂COO)(μ₂-FcCONHCH₂COO)(2,2′-bipy)(H₂O)] _n (3) (FcCOOH?=?ferrocenemonocarboxylic acid, FcCONHCH₂COOH?=?N-ferrocenylformylglycine, phen?=?1,10-phenanthroline, 2,2′-biby?=?2,2′-bipyridine), were synthesized and characterized by elemental analysis, IR, and single crystal X-ray diffraction analysis. Structural studies revealed that 1 and 2 have similar binuclear structures, but 3 exhibits a 1-D chain structure. The difference in the structures of ferrocenylcarboxylate-containing cadmium(II) complexes is due to steric hindrance of ferrocenyl groups.     

Two cadmium(II) addition compounds with 3-hydroxy-2,7-naphthalenedisulfonate containing aromatic diamines and their 3-D net

{[CdCl(2,2′-bipy)₂(H₂O)]⁺·[Cd(3-O^?-2,7-NDS)(2,2′-bipy)₂]^?·3H₂O} (1) and {[Cd(phen)₃]²⁺·2[Cd(3-O^?-2,7-NDS)(phen)₂]^?·8.5H₂O} (2) (3-OH-2,7-NDS?=?3-hydroxy-2,7-naphthalenedisulfonate, phen?=?1,10-phenanthroline, and 2,2′-bipy?=?2,2′-bipydine) were prepared and characterized by X-ray single-crystal diffraction. Compound 1 contains a discrete coordination cation [CdCl(2,2′-bipy)₂(H₂O)]⁺ and a coordination anion [Cd(3-O^?-2,7-NDS)(2,2′-bipy)₂]^?; 2 contains a discrete coordination cation [Cd(phen)₃]²⁺ and two coordination anions [Cd(3-O^?-2,7-NDS)(phen)₂]^?. There are numerous weak interactions among the coordination cation, coordination anion, and free water molecules, such as O–H?···?O hydrogen bonds, π?···?π stacking, and Cl^??···?π interactions in 1 and π?···?π stacking and C–H?···?π interactions in 2. The cations and anions as building blocks are connected to construct different 3-D supramolecular architectures via weak intermolecular interactions. Particularly, the capsule structure of 1 was observed.     

Syntheses and structures of three coordination polymers based on 4-methylbenzenethiolates of Zn(II) and Cd(II) and bipyridine

Using 4-methylbenzenethiolates of Zn or Cd as precursors and 4,4′-bipyridine (4,4′-bpy) as bridges, we have synthesized three new Zn(II)/Cd(II) coordination polymers, {[Cd(4,4′-bpy)₂(NCS)₂] · 2(SC₆H₄CH₃-4)₂} _n (1), {[Zn(4,4′-bpy)(SC₆H₄CH₃-4)₂] · DMF} _n (2) and {[Zn(4,4′-bpy)(SC₆H₄CH₃-4)₂] · H₂O · 0.5CH₃OH} _n (3). Compound 1 is a 2-D sheet-like square polymer in which four 4,4′-bpy ligands and two isothiocyanate ligands complete the octahedral Cd(II) coordination sphere. Compounds 2 and 3 have similar coordination around Zn(II), but have different polymer structures. In 2, Zn(II) centers are linked via a bidentate 4,4′-bipyridine to form 1-D twisted arched chains, which is a new structural type for Zn(II). Compound 3 has 1-D zigzag chains. The 2-D sheets in 1 and 1-D chains in 2 and 3 are assembled via intermolecular C–H ··· π and C–H ··· S interactions into 3-D supramolecular networks. C–H ··· S interactions are a vital factor in constructing the sulfur-containing coordination polymers. Different coordination modes and packing schemes in 1–3 show that the guest molecule has a critical influence on formation of polymers.     

Syntheses,crystal structures,and fluorescent properties of two Cd(II) complexes based on 2,2′-(ethane-1,2-diyl)bis(1H-imidazole-4,5-dicarboxylic acid)

Two new complexes, [Cd₂(H₄ebidc)₂(CH₃OH)₄]?·?2CH₃OH (1) and {[Cd(Cl)(I)(H₆ebidc)_1/2]?·?1/2bbe?·?H₂O} _n (2) (H₆ebidc?=?2,2′-(ethane-1,2-diyl)bis(1H-imidazole-4,5-dicarboxylic acid), bbe?=?1,2-bis(2-benzimidazolyl)ethane), are obtained through self-assembly of H₆ebidc with Cd(II). Single-crystal X-ray diffraction shows that 1 has a binuclear structure and each tridentate chelating ligand coordinates to two Cd(II) ions with µ₂-O. Complex 2 displays a 1-D chain structure and each tetradentate ligand bridges two Cd(II) ions in chelating fashion. Fluorescent properties have also been determined.     

Syntheses,crystal structures,and photoluminescence of two Cd(II) complexes with simple ligands

Two cadmium complexes, {[Cd₂(2,5-tda)₂(ip)₄]·4H₂O}_n (1) and {[Cd₂(4,4′-obb)₂(ip)₂·H₂O]·H₂O}_n (2) (2,5-tda?=?thiophene-2,5-dicarboxylic acid, 4,4′-obb?=?4,4′-oxybisbenzoic acid, ip?=?1H-imidazo[4,5-f][1, 10]-phenanthroline), were synthesized and characterized by IR, elemental analysis, powder X-ray diffraction, and single-crystal X-ray diffraction. X-ray analysis revealed that 1 is a dinuclear complex with the 2,5-tda anion connecting two Cd ions in a μ₁-η¹:η⁰/μ₁-η¹:η⁰ coordination mode. Each dinuclear complex is further connected with neighboring complexes via hydrogen-bonding interactions. Compound 2 displays a 2-D layer structure with opened windows occupied by crystallographic water molecules. The layers are further packed via hydrogen-bonding interactions. Luminescent properties for 1 and 2 are also investigated in the solid state at room temperature.     

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.     

1-D zigzag double-chain coordination polymers of transition metals derived from pyridine-2,3,5,6-tetracarboxylic acid

Three new 1-D zigzag coordination polymers {[M₂(pdtc)(bpy)₂(H₂O)₃]?·?4H₂O} _n [M?=?Zn (1), Ni (2), Co (3)] (H₄pdtc?=?pyridine-2,3,5,6-tetracarboxylic acid, bpy?=?2,2′-bipyridine) have been synthesized by the reactions of H₄pdtc and corresponding metal salts in the presence of bpy at room temperature and characterized by elemental analyses, IR, TGA, fluorescence, and X-ray diffraction. The main structural feature of 1–3 is the presence of octahedrally coordinated M1(II) and M2(II) centers sequentially bridged by pdtc ligands; bpy acts as a blocking ligand to avoid further polymerization. These coordination modes lead to 1-D double-chain structures. The 2-D or 3-D supramolecular structures of 1–3 are built up by π?···?π and hydrogen-bond interactions. Two (H₂O)₃ clusters are observed in 1–3. The zinc complex shows strong fluorescent emission at 325?nm.     

Syntheses,crystal structures,and optical properties of a series of transition metal coordination polymers with chelidamic acid and 4,4′-bipyridine

A series of transition metal (Zn, Cu, Mn) complexes with chelidamic acid (2,6-dicarboxy-4-hydroxypyridine, H₃CAM) and 4,4′-bipyridine (bipy), [Zn₂(bipy)Cl₂] _n (1), {[Zn₂(HCAM)(H₂CAM)₂]?·?(bipy)?·?3.5H₂O} _n (2), [Mn₃(HCAM)₃(H₂O)₇]?·?(bipy)?·?3H₂O (3), [Mn₂(HCAM)₂(bipy)?·?(H₂O)₂]?·?4H₂O (4), [Cu₂(HCAM)₂(bipy)?·?(H₂O)₂]?·?4H₂O (5), and Cu₂(HCAM)₂(bipy)?·?(H₂O)₂ (6), have been synthesized by hydrothermal or solution methods and characterized by single-crystal X-ray diffraction. The structural analyses reveal that 1 exhibits a zigzag chain of Zn(II), Cl^?, and 4,4′-bipyridine. In 2, a 1-D polymeric [Zn₂(HCAM)(H₂CAM)₂] _n chain and a discrete 4,4′-bipyridine assemble into a 2-D supramolecular network via H-bonds. Complex 3 consists of asymmetric units of Mn₃(HCAM)₃(H₂O)₇ that are linked by hydrogen bonds to form a 2-D H-bonded network. Complexes 4–6 are isomorphous and possess discrete structures. The photoluminescent properties of 1–6 at room temperature were studied.