Supramolecular assembly of three Ag(I) coordination polymers derived from flexible N-containing ligands and polycarboxylates: synthesis,structures, and catalytic properties

Three Ag(I) coordination polymers [Ag(L1)]·(H₃bptc)·H₂O (1), [Ag₂(L2)(oba)]·H₂O (2), and [Ag₂(L2)₂]·(H₂bptc) (3) [L1 = 1,4-bis(3,5-dimethylpyrazole)butane, L2 = 1,4-bis(2-methylbenzimidazole)butane, H₄bptc = 3,3′,4,4′-biphenyltetracarboxylic acid, H₂oba = 4,4′-oxybis(benzoic acid)] constructed from N-containing ligands with different flexibilities and organic carboxylates as co-ligands have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis. All three complexes display 1D chain structures, which are further extended into 2D supramolecular networks via non-classical C–H···O hydrogen bonding interactions. The fluorescence and catalytic properties of the complexes 1–3 have been investigated in detail. Complexes 2 and 3 reveal promising catalytic activities for the degradation of methyl orange in a Fenton-like process.     

Coordination assemblies of rigid–flexible 1,3-bis(5-(pyridine-2-yl)-1,2,4-triazole-3-yl)propane ligands with MCl<Subscript>2</Subscript> (M = Fe,Co, Cu or Zn): structural diversity and mass spectra

Reactions of the rigid–flexible N-heterocycle 1,3-bis(5-(pyridine-2-yl)-1,2,4-triazole-3-yl) propane (H₂L) with MCl₂ (M = Fe, Co, Cu or Zn) gave coordination complexes, {[Fe ₂ ^III Cl₄(H₂L)₂]·2Cl}·EtOH·H₂O (1), {[Co₃Cl₅(HL)]·H₂O} _n (2), {[Co₄Cl₄(H₂L)₂(H₂O)₄]·[CoCl₄]₂}·H₂O (3), [Cu₂Cl₃(HL)(H₂O)]₆·5H₂O (4), [Cu ₂ ^II Cu^ICl₄(HL)] _n (5), {[Zn₂Cl₂(L)H₂O]·H₂O} _n (6) and [Zn₄Cl₆(HL)₂] (7), which have been characterized by single-crystal X-ray diffraction. Structural analysis reveals that the pyridine triazole ligand attains versatile coordination modes in these complexes. Complexes 1, 3, 4 and 7 consist of 0D clusters with binuclear or tetranuclear units; complex 2 presents a 2D network accompanied by HL^? and chloride bridges; complexes 5 and 6 show 1D chains with [Cu₃] and [Zn₂] subunits. In addition, the electrospray ionization mass spectrometry properties of selected complexes were investigated, revealing the stabilities and structural states of these complexes in solution. These results indicate that H₂L is an excellent multiconnection linker for the construction of diverse coordination complexes.     

Synthesis,Crystal Structures and Magnetic Properties of Three New Polynuclear Cu(II) Complexes Based on the Methoxybenzoate Isomers

In this paper, self-assembly reactions of copper(II) ions, methoxybenzoate isomers and 2,2′-bipyridine yield two copper-oxygen polynuclear complexes: [Cu₂(bpy)₂(2-C₈H₇O₃)₃]·(2-C₈H₇O₃)·14H₂O 1, [Cu₄(bpy)₄(H₂O)(OH)₄]·4(3-C₈H₇O₃)·17H₂O 2, and a simple mononuclear complex [Cu(bpy)(H₂O)(4-C₈H₇O₃)₂] 3. (bpy = 2,2′-bipyridine, C₈H₇O₃ = methoxybenzoate ion). Single crystal X-ray diffraction analyses reval that compound 1 is a dinuclear copper(II) complex which bridged by three carboxylate groups, and 2 presents a discrete step-like tetra-nuclear copper Cu₄O₄ core. Compound 3 shows a square pyramidal mononuclear geometry. The magnetic susceptibility of complex 1 measured from 2 to 300 K, revealed an antiferromagnetic interaction between the Cu(II) ions. Furthermore, the results about IR spectra and thermal analyses were discussed.     

Structural versatility and electrochemical properties of four copper(II) complexes based on 1<Emphasis Type="Italic">H</Emphasis>-indazole-3-carboxylic acid

Copper (Cu)(II) complexes were synthesized by Ind-3-COOH combined with N-containing auxiliary ligands via a combinatorial strategy involving hydrothermal and solvent-evaporation method. The synthesized complexes had the following formulas: [Cu(Ind-3-COO)₂] (1), [Cu(PHEN)(Ind-3-COO)]₂·2H₂O (2), [Cu₂(DPP)(Ind-3-COO)₂(H₂O)]·H₂O, (3) and [Cu(BPY)(Ind-3-COO)₂]·4H₂O (4). Meanwhile, the symbol abbreviations were listed as follows: Ind-3-COOH = 1H-indazole-3-carboxylic acid, 1,3-bis(4-pyridyl)propane (DPP), 1,10-phenanthroline (PHEN) and 4,4′-bipyridine (BPY). The crystalline structure and spectroscopy of each complex were characterized by single-crystal X-ray diffraction, elemental analysis, Fourier transform infrared spectroscopy and powder X-ray diffraction. The redox reactions in the complexes were then investigated by performing cyclic voltammetry under nitrogen conditions at room temperature. Two pairs of distinctive irreversible reduction potentials were identified, which could be attributed to the processes of Cu(II)–Cu(I) and Cu(I)–Cu(0).     

Diverse topologies of three cobalt(II) coordination polymers constructed from flexible bis(benzimidazole) and dicarboxylate ligands

Three cobalt(II) coordination polymers {[Co(L1)(nda)(H₂O)₂]·2H₂O} _n (1), [Co(L2)(tbi)(H₂O)] _n (2) and [Co(L2)(bpdc)(H₂O)] _n (3) (L1 = 1,3-bis(5,6-dimethylbenzimidazol-1-yl)-2-propanol, L2 = 1,3-bis(benzimidazol-1-yl)-2-propanol, H₂nda = 2,6-naphthalenedicarboxylic acid, H₂tbi = 5-tert-butyl isophthalic acid and H₂bpdc = 4,4′-biphenyldicarboxylic acid) were synthesized and characterized by physicochemical and spectroscopic methods. Complex 1 exhibits a 1D loop-like structure, which is further extended into a 3D 3,3,4T31 network through two O–H···O hydrogen bonding interactions. Complex 2 displays a 1D ladder-like chain, arranged into a 2D supramolecular network with 3,3,4L34 topology via classical O–H···O hydrogen bonding interactions, whereas complex 3 features a 2D 3,4L13 layer structure and further assembles into a 3D framework with a twofold interpenetrating sqc65 topology through O–H···O hydrogen bonding interactions. The fluorescence and catalytic properties of these complexes for the degradation of Congo red in a Fenton-like process have been investigated.     

Synthesis,crystal structures,and properties of copper(II) dicarboxylate complexes with [bis(2-pyridylcarbonyl)amido]

Four new complexes, [Cu₂(Bpca)₂(L¹)(H₂O)₂] · 3H₂O (I), [Cu₂(Bpca)₂(L²)(H₂O)₂] (II), [Cu₂(Bpca)₂(L³)] · 2H₂O (III), [Cu₂(Bpca)₂(L¹)(H₂O)] · 2H₂O (IV) (Bpca = bis(2-pyridylcarbonyl)amido, H₂L¹ = glutaric acid, H₂L² = adipic acid, H₂L³ = suberic acid, H₂L⁴ = azelaic acid) have been synthesized and characterized by single-crystal X-ray diffraction methods (CIF files CCDC nos. 1432836 (I), 1432835 (II), 817411 (III), and 817412 (IV)), elemental analyses, IR spectra. Structural analyses reveal that compounds I, II, and IV have similar structures [Cu(Bpca)]⁺ units bridged by dicarboxylate forming dinuclear units, whereas the dinuclear of compound III are edge-shared through two carboxylate oxygen atoms of different suberate anions. Hydrogen bonds are response for the supramolecular assembly of compounds I to IV. The temperature-dependent magnetic property of III was also investigated in the temperature range of 2 to 300 K, and the magnetic behaviour suggests weak antiferromagnetic coupling exchange.     

Two novel coordination polymers: Synthesis,structure, luminescent properties,and selective sensing of Cu<Superscript>2+</Superscript> and Mn<Superscript>2+</Superscript> ions

Two novel coordination polymers, namely {[Co(Ttac)_0.5(1,4-Bib)(H₂O)] · H₂O}_n (I) and {[La(HTtac)₂(2H₂O)] · H₂O}n (II) (H4Ttac = 4,5-di(3'-carboxylphenyl)-phthalic acid, 1,4-Bib = 1,4-bis(1-imidazoly) benzene), have been designed and successfully prepared via hydrothermal process, and characterized by elemental analyses, IR spectroscopy, and single crystal X-ray diffraction (CIF files CCDC nos. 1039298 (I), 1039300 (II)). Structural analysis reveals that the H₄Ttac ligands adopt different coordination modes in the as-synthesized I and II, and thus give rise to the targeted coordination polymers with different configurations. It is worth mentioning that, coordination polymer I is assembled from low-dimensional structures into three-dimensional (3D) via π···π stacking interactions, while three-dimensional coordination polymer II is formed by covalent bonds. Luminescent properties of coordination polymer II have been studied at ambient temperature. Significantly, luminescent measurement indicates that coordination polymer II may be acted as potential luminescent recognition sensors towards Cu²⁺ and Mn²⁺ ions.     

Synthesis,characterization, and crystal structures of 2D cobalt(II) and nickel(II) coordination polymers containing flexible bis(benzimidazole) ligands

Three coordination polymers, namely {[Ni(L1)(nip)(H₂O)]·2H₂O} _n (1), [Co(L2)(tbip)] _n (2), and {[Co₂(L3)₂(bptc)]·3H₂O} _n (3) (L1 = 1,4-bis(5,6-dimethylbenzimidazole)butane, L2 = 1,4-bis(5,6-dimethylbenzimidazole)-2-butylene, L3 = 1,3-bis(5,6-dimethylbenzimidazole)propane, H₂nip = 5-nitro-isophthalic acid, H₂tbip = 5-tert-butyl-isophthalic acid, H₄bptc = biphenyl-3,3′,4,4′-tetracarboxylic acid), have been synthesized under hydrothermal conditions and characterized by physicochemical and spectroscopic methods as well as by single-crystal X-ray diffraction analysis. Complexes 1 and 2 both feature a two-dimensional (4,4) layer with (4⁴ × 6²) topology. Complex 3 possesses a uninodal 4-connected 2D htb network. The fluorescence spectra and catalytic properties of the complexes for the degradation of methyl orange by sodium persulfate in a Fenton-like process are reported.     

Influence of anions on copper(II) complexes of a flexible bis-pyridyltrazole ligand: identification of a discrete water–chloride cluster [(H<Subscript>2</Subscript>O)<Subscript>10</Subscript>(Cl)<Subscript>8</Subscript>]<Superscript>8−</Superscript>

Three Cu(II) complexes, [Cu(H₂L)(ClO₄)₂] (1), [Cu(H₂L)_0.5(µ-SO₄)(H₂O)]·H₂O (2) and [{Cu(H₂L)(H₂O)}{Cu(H₂L)(Cl)]Cl₃·4H₂O (3), with a flexible ligand 1,2-bis(5-(pyridine-2-yl)-1,2,4-triazole-3-yl)ethane (H₂L) were synthesized from various Cu(II) salts. X-ray crystal structure analysis reveals that the H₂L ligand demonstrates different coordination modes in each of these complexes. Complex 1 shows a mononuclear structure with ClO₄ ^? anions weakly coordinated to the metal center, which is further extended into a 1-D assembly through hydrogen bonds. Complex 2 is a polymeric species in which the dinuclear units [Cu₂(H₂L)(H₂O)₂] are linked through SO₄ ^2? anions to form 1-D chains, which are further associated into a 2-D assembly through a self-assembled decameric water cluster. Complex 3 features an interesting 3-D coordination architecture assembled through extensive hydrogen interactions between chloride anions and water molecules. Notably, a unique discrete water–chloride cluster [(H₂O)₁₀(Cl)₈]^8? built around a chair-like water–chloride octameric core is identified in the crystal matrix of complex 3. The choice of counteranion plays a key role in the diverse structures of these complexes. The spectroscopic properties of the complexes have also been investigated.     

Syntheses,structures and properties of complexes of indole-3-propionic acid

Three complexes [Zn₂(IPA)₂(phen)₄](HIPA)₂(NO₃)₂·H₂O (1), {[Zn(IPA)₂(bipy)]·3H₂O}_n (2), and {[Mn(IPA)₂(bipy)(H₂O)]·2H₂O}_n (3) (HIPA = indole-3-propionic acid, phen = 1,10-phenanthroline, bipy = 4,4′-bipyridine) were synthesized and characterized by physico-chemical and spectroscopic methods. Complex 1 displays a zero-dimensional structure, whilst 2 and 3 show one-dimensional chains, which are linked into supramolecular networks through hydrogen bonding interactions and/or π···π stacking interactions. The luminescence properties of complexes 1 and 2 were investigated.     

Comprehensive comparison between the reaction of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>'-cyclohexane-1,2-diylidene-bis(4-methoxybenzoylhydrazide) with mercury(II) and copper(II) ions. Synthesis,structure, and kinetics of complex formation

Comprehensive comparison between the reaction of N,N'-cyclohexane-1,2-diylidene-bis(4-methoxybenzoylhydrazide) (CHMBH) with HgCl₂ and Cu(NO₃)₂ · 2.5H₂O salts have been investigated, including the synthesis, structure and kinetic of complex formation. The reactions of CHMBH with HgCl₂ or Cu(NO₃)₂ · 2.5H₂O at the same synthetic conditions have been shown to produce completely different type of complexes: [Hg(CHMBH)Cl₂] · CH₃CN (I) and [Cu₃(μ₃-OH)(CTMB)₃(NO₃)₂(CH₃CN)₂] · 5CH₃CN · H₂O (II) (CTMB = cyclohexotriazole-3-(4-methoxybenzamide)). The prepared compounds were characterized using different techniques (NMR, IR, UV-Vis and mass spectroscopies, microelemental analysis, thermogravimetry as well as X-ray powder differection and X-ray single crystal crystallography for I (CIF file CCDC no. 1503398). X-ray crystallography shows that the isolated product of I is a mononuclear complex which contains the [Hg(CHMBH)]²⁺ core. While, the isolated product of II was a trinuclear Cu(II) cluster [Cu₃(μ₃-OH)(CTMB)₃(NO₃)₂(CH₃CN)₂] · 5CH₃CN · H₂O which contains three differently coordinated copper sites. Kinetic studies on the formation of I have been also investigated and compared with that of II. In case of I, the reaction was so slow and exhibits a first-order dependence on the concentration of metal salt and a first-order dependence on the concentration of CHMBH. While in II, the study shows that the reaction is fast and occurs in three distinct phases.     

Homo- and heteronuclear iron complexes {Fe<Subscript>2</Subscript>MO} with salicylic acid: Synthesis,structures, and physicochemical properties

A reaction of iron nitrate with magnesium salicylate and reactions of iron and cobalt chlorides with ammonium salicylate in the presence of water, methanol, DMAA, and DMF gave the trinuclear heterometallic complexes: [hexa-μ-salicylato-μ₃-oxo-0.4-dimethylacetamide-2.6-aquadiiron(III)magnesium(II)] tetra(dimethylacetamide), [Fe₂MgO(SalH)₆(DMAA)_0.4(H₂O)_2.6]·4DMAA (I); [hexa-μ]-salicylato-μ₃-oxo(dimethanol)aquadiiron(III)cobalt(II)] dimethylformamide · 2.5-hydrate, [Fe₂CoO(SalH)₆(CH₃OH)₂(H₂O)] · DMF · 2.5H₂O (II); and [hexa-μ-salicylato-μ₃-oxotriaquatriiron(III)] chloride dimethylacetamide monohydrate, [Fe₃O(SalH)₆(H₂O)₃]Cl · DMAA · H₂O (III). The X-ray study revealed that the molecular structures of complexes I and II are [Fe₂ ^IIIM^II(μ₃-O)(RCOO)₆L₃] · nSolv. The IR and Mössbauer spectra of complexes I–III were examined; their magnetochemical and thermal properties were studied. The parameters of the Mössbauer spectra (δ_Na ⁺ = 0.69 ± 0.03 mm/s, ΔE _Q = 0.76–1.08 mm/s, 300 K) suggest the high-spin state of the Fe³⁺ ions in complexes I–III (S = 5/2). The paramagnetic Fe³⁺ ions are involved in antiferromagnetic exchange interactions with the parameter J = ?44 cm^?1, g = 2.05 (for I). Complexes I–III are thermally unstable.     

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

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 N_pyridyl–H···N_SCN interactions, H₂(L2)²⁺ and CdI₂(SCN) ₂ ^2? 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.     

One Dinuclear Copper(II) Polymer Based on <Emphasis Type="Italic">N</Emphasis>-(Pyridine-3-Sulfonyl Amino)-Acetate: Synthesis,Structure, and Magnetic Analysis

The reaction of CuCl₂ · 2H₂O with N-(pyridine-3-sulfonyl amino)-acetate (H₂L) in ethanol, water and 4,4′-Bipy under solvothermal conditions leads to the formation of a dinuclear copper polymer {[Cu₂(L)₂(4,4′-Bipy)(H₂O)₂] · H₂O · CH₃OH} _n (I). The polymer was characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and X-ray single-crystal diffraction (CIF file CCDC no. 1543747). The results showed that polymer belongs to the triclinic system, \(P\bar 1\) space group. TG curve shows that polymer I first removes water molecules, and then the ligand split for polymers I, and the remained residue is CuO. The magnetic measurement reveals the N-(pyridine-3-sulfonyl amino)-acetate as bridge ligand can mediate the antiferromagnetic coupling interaction between magnetic centers.     

Substituted group-directed assembly of six coordination compounds based on pyrazole bifunctional ligands

Six new complexes [Mn₈(μ₄-O)₄(phpz)₈(MeOH)₄]·(MeOH)(H₂O) (1) [Co₂(HphpzH)(Hphpz)₂(phpz)₂]·4(MeOH) (2), Ni(Hphpz)₂ (3), [Ni(Hphpz)₂]·H₂O (4), [Zn₄(pzpy)₄Cl₄] (5) and [Cu₂(pzpy)₂(HCO₂)₂(H₂O)₂] (6) have been synthesized by hydrothermal reactions of MCl₂·4H₂O (M = Mn, Co, Ni, Zn or Cu) with 5-(2-hydroxyphenyl)-3-pyrazole (HphpzH) or 2-(1H-pyrazol-3-yl)pyridine (Hpzpy). The complexes were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Complex 1 is an octanuclear Mn(III) cluster, complexes 2 and 6 are binuclear Co(III) and Cu(II), respectively, complexes 3 and 4 are isomorphous mononuclear species, while complex 5 is a tetranuclear Zn(II) cluster. The magnetic behavior of complex 1 was investigated. Magnetic susceptibility measurements revealed antiferromagnetic exchange interactions between the metal centers in the clusters. The luminescence properties of the complexes were investigated at room temperature in the solid state.     

Cobalt(II) complexes with pentadentate Schiff bases 2,6-diacetylpyridine hydrazones: Syntheses and structures

Seven new cobalt(II) complexes based on the Schiff bases, 2,6-diacetylpyridine bis(isonicotinoylhydrazone) (H₂L¹) and 2,6-diacetylpyridine bis(nicotinoylhydrazone) (H₂L²), are synthesized and studied by X-ray diffraction analysis: [Co(H₂L¹)(NCS)₂] · 2.25H₂O (I), [Co(H₂L²)(NCS)₂] · CH₃OH (II), [Co(H₂L²)(NCS)(H₂O)]NCS (III), [Co(H₄L¹)(NCS)₂](NO₃)₂ · 2H₂O (IV), [Co(H₄L¹)(NCS)₂][Co(NCS)₄] · 0.75H₂O (V), [Co(H₄L²)(NCS)₂][Co(NCS)₄] · 1.75H₂O (VI), and [Co(H₂L²)(NCS)(CH₃OH)]₂[Co(NCS)₄] · 2CH₃OH (VII) (CIF files CCDC 941186 (I), 1457906 (Ia), 1457905 (II), 941187 (III), 1457907 (IV), 1457908 (V), 1457909 (VI), and 941188 (VII)). The organic ligands in the complexes act as pentadentate neutral H₂L or doubly protonated (H₄L)²⁺ coordinated through the same set of donor atoms N₃O₂. In all compounds I–VII, the coordination polyhedron of the Co²⁺ ion in a complex with the Schiff bases has a shape of a pentagonal bipyramid. The hydrazones are arranged in the equatorial plane of the bipyramid. Its axial vertices are occupied by the nitrogen atoms of the NCS￣ anions in compounds I, II, and IV–VI and by the nitrogen atoms of NCS￣ and oxygen of the water molecule in compound III or methanol in compound VII. The NO ₃ ^- anions or [Co(NCS)₄]^2￣ complex anions obtained by the reactions are involved along with the NCS￣ anions in the formation of compounds IV–VII.     

Synthesis,crystal structures,luminescence, and photocatalytic properties of two 1D Co(II) coordination polymers constructed with semirigid bis(benzimidazole) and dicarboxylate ligands

Two ternary cobalt(II) coordination polymers (CPs), namely [Co(L1)(npht)] _n (1) and {[Co₂(L2)₂(npht)₂(H₂O)]·H₂O} _n (2) (L1 = 4,4′-bis(benzimidazol-1-ylmethyl)biphenyl, L2 = 1,2-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, and H₂npht = 4-nitrophthalic acid) have been synthesized and structurally characterized by X-ray crystallography. Both CPs feature similar 1D infinite chains containing two distinct loops. CP 1 further forms a 3D supramolecular network via weak C–H···O hydrogen bond interactions. CP 2 shows a 1D two-layer chain structure, assembled through π–π stacking interactions. The electrochemical, luminescence, and photocatalytic activities of the two CPs for the removal of methylene blue under visible or UV light were investigated. Possible photocatalytic mechanisms are discussed.     

Four novel metal–organic frameworks based on 3,4,7,8-tetramethyl-1,10-phenanthroline: Syntheses,structures, and thermal properties

Four novel metal–organic frameworks, [Cu(Tmp)₂(H₂O)] · NO₃ (I) (Tmp = 3,4,7,8-tetramethyl-1,10-phenanthroline), [Mn(Tmp)₂(H₂O)₂] · 2NO₃ · H₂O (II), [Pb(Tmp)(CH₃COO)₂] · 3H₂O (III) and [Zn(Tmp)₂(H₂O)₂] · 2NO₃ · 2H₂O (IV), have been synthesized and characterized by single crystal X-ray diffraction (CIF files CCDC nos. 88362–88365 for I–IV, respectively), IR spectroscopy, elemental analysis and thermogravimetric analysis. Both I and II complexes are crystallized in monoclinic system with space groups C2/c, P2₁/c, respectively, while III and IV complexes are crystallized in triclinic system with space groups \(P\overline 1 \). Generally, these crystal structures are stabilized by O–H···O hydrogen bonds and π–π interactions between the phenanthroline rings of neighboring molecules. Thermogravimetric analyses of compounds I–IV display considerable thermal stability.     

Synthesis,crystal structures,adsorption and fluorescence properties of coordination polymers based on a semirigid octadentate ligand

Using an octadentate ligand, namely tetrakis[(3,5-dicarboxyphenoxy)methyl] methane (H₈L), four coordination polymers, [Ni₃L(OH)₂(H₂O)₂][NH₂(CH₃)₂]₄·5H₂O (1), [Co₄L(H₂O)₄]·9H₂O (2), [Zn₄L(H₂O)₄]·DMF·11H₂O (3) and [Li₄(H₄L)(H₂O)₄] (4) (DMF = N,N-dimethylformamide), have been solvothermally synthesized and structurally characterized by X-ray crystallography. Complex 1 is an anionic three-dimensional open framework built from tricluster {Ni₃(COOR)₈} and square planar L ligands to give a uninodal 6-connected pcu network. Complexes 2 and 3 are isostructural, possessing a non-interpenetrated three-dimensional network with rare (4,8)-connected scu topology. Complex 4 consists of 4-connecting {Li₂(COOR)₄} clusters which form a 2D Shubnikov tetragonal plane net with sql topology. Complexes 1–3 all have large solvent accessible voids, but only complex 3 possesses permanent porosity as confirmed by N₂, H₂, CO₂ and CH₄ gas adsorption measurements. In addition, complex 3 shows strong photoluminescent emissions at room temperature with a peak at 365 nm, owing to a ligand-centered excited state. The emission intensities of 3 varied upon contact with different solvents or analytes.     

Three 2D mixed-ligand Co(II) coordination polymers containing flexible bis(benzimidazole) ligands with different spacers

Three new Co(II) coordination polymers, [Co(L1)(bpdc)] _n (1), [Co(L2)(ndc)(H₂O)·2H₂O] _n (2) and [Co(L3)(ndc)(H₂O)·H₂O] _n (3) (L1 = 1,2-bis(5,6-dimethylbenzimidazole)ethane, L2 = 1,3-bis(5,6-dimethylbenzimidazole)propane, L3 = 1,4-bis(5,6-dimethylbenzimidazole)butane, H₂bpdc = 4,4′-biphenyldicarboxylic acid, H₂ndc = 2,6-naphthalenedicarboxylic acid) have been synthesized under hydrothermal conditions and structurally characterized by X-ray crystallography. All three complexes feature (4,4) networks that extend into 3D supramolecular frameworks via hydrogen bonding interactions. The luminescence properties and catalytic activities of these complexes with respect to the degradation of methyl orange in a Fenton-like process have been investigated.