Syntheses, structures and properties of silver(I) complexes with flexible 1,3,5-tris(pyridylmethoxyl)benzene ligands

Five new silver(I) complexes [Ag₂(L₂)₂](BF₄)₂·CH₃CN·CH₃OH (1), [Ag(L₂)(CF₃SO₃)] (2), [Ag(L₃)]ClO₄·CH₃OH (3), [Ag₂(L₃)₂](CF₃SO₃)₂·CH₃CN·CH₃OH·H₂O (4) and [Ag(L₃)]PF₆·2CH₃CN (5) [L₂=1,3,5-tris(2-pyridylmethoxyl)benzene, L₃=1,3,5-tris(3-pyridylmethoxyl)benzene] were synthesized and characterized by single crystal X-ray diffraction analyses. In complexes 1-5, ligands L₂ and L₃ show different conformations and act as three-connectors, while the Ag(I) atom serves as three-connecting node to result in the formation of 2D and 3D frameworks. Complexes 1 and 2 with different counteranions have similar 2D network structure with the same (4,8²) topology. Complex 3 has a 3D structure with (10,3)-a topology while complexes 4 and 5 have the same 2D (6,3) topological structure. The results showed that the structure of organic ligands and counteranions play subtle but important role in determining the structure of the complexes. In addition, the photoluminescence and anion-exchange properties of the complexes were investigated in the solid state at room temperature.     

Syntheses,structures, and photoluminescence of three cadmium(II) coordination polymers with flexible bis(benzimidazole) ligands

Three cadmium(II) coordination polymers, [CdBr₂(L₁)] _n (1), [CdI₂(L₂)] _n (2), and Cd₂Br₄(L₃)₂ (3), where L₁?=?1,3-bis(5,6-dimethylbenzimidazole)propane, L₂?=?1,4-bis(5,6-dimethylbenzimidazole)butane, and L₃?=?1,6-bis(5,6-dimethylbenzimidazole)hexane, have been synthesized by hydrothermal methods and characterized by elemental analyses, IR spectra, TGA, PXRD, and X-ray crystallographic diffraction. Complex 1 contains a 1-D helical chain in which CdBr₂ units are linked by L₁. For 2, each CdI₂ is connected by two different conformations of L₂ to form a 1-D zigzag chain. For 3, each CdBr₂ is linked by L₃ bridges to afford a binuclear structure. These results indicate that the spacer length of the ligands play important roles in assembly of Cd(II) coordination polymers. Thermogravimetric analyses and solid-state luminescent properties of the complexes have also been investigated.     

Syntheses,structures, photoluminescences of silver(I) coordination polymers with 2-aminopyrazine and varied dicarboxylate ligands

Four new silver(I) coordination polymers, namely [Ag(NH₂pyz)(ox)_0.5]_n (1), [Ag(NH₂pyz)(adp)_0.5·2H₂O]_n (2), [Ag₂(NH₂pyz)₂(bdc)·H₂O]_n (3) and [Ag₂(NH₂pyz)_2.5(ndc)]_n (4) [NH₂pyz = 2-aminopyrazine, ox = oxalate anion, adp = adipate anion, bdc = 1,4-benzenedicarboxylate anion, ndc = 1,4-naphthalenedicarboxylate anion] have been synthesized by solution phase ultrasonic reactions of Ag₂O with heterocyclic NH₂pyz and various dicarboxylates under ammoniacal conditions. The complexes were characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction. Complex 1 is a three-dimensional (3D) framework with an α-ThSi₂ topology. Complex 2 features a 2D 4⁴-sql net involving infinite 1D double Ag-NH₂pyz chains and flexible adp anion spacers. Complex 3 is a 3D framework in which 1D single Ag-NH₂pyz chains are pillared by bdc anions to form a 2D 6³-hcb network, adjacent 2D networks are packed into a 3D framework through bridging O atoms of dbc anions. Complex 4 is a 2D structure built from infinite 1D stair-like chains containing finite Ag₄(NH₂pyz)₅ subunits. The results show that the structural diversity of the complexes result from the nature of the dicarboxylate ligands. The photoluminescence properties of the complexes were also investigated in the solid state at room temperature.     

Extended chains via hydrogen bond linkages of dinuclear copper(II) and cadmium(II) complexes with a new flexible disulfoxide ligand

A new flexible disulfoxide ligand 1,6-bis(benzylsulfinyl)hexane (L), which is a mixture of the meso and rac isomers, was treated with Cu^II or Cd^II nitrate and obtained dimeric complex [Cu₂(L)₃(H₂O)₂(NO₃)₄] 2 or [Cd₂(L)₃(H₂O)₂(NO₃)₄] 3. In the reacting system the crystals of meso isomer 1 of L together with 2 or 3 were obtained. 2 and 3 have similar molecular structures. In the neutral dimer, three ligands present two kinds of coordination models: monodentate and bis-monodentate. The neutral dimeric units in 2 and 3 are linked by hydrogen bonds to yield a chain structure. Crystal structures of all three compounds were determined by single-crystal X-ray diffraction methods. Crystal data for 1: monoclinic, space group Cc, a=41.95(2), b=5.132(2), c=8.660(4) Å, β=94.898(9)°, V=1857.7(15) Å³, Z=4, final refinement (I>2σ(I)): R1=0.0659, wR2=0.1415. Crystal data for 2: triclinic, space group P-1, a=9.242(4), b=9.539(4), c=21.042(9) Å, α=83.888(9), β=87.971(8), γ=74.177(9)°, V=1774.6(13) Å³, Z=2, final refinement (I>2σ(I)): R1=0.0577, wR2=0.0954. Crystal data for 3: triclinic, space group P-1, a=9.203(4), b=9.831(3), c=20.860(7) Å, α=84.313(6), β=86.432(7), γ=74.188(6)°, V=1805.9(11) Å³, Z=2, final refinement (I>2σ(I)): R1=0.0548, wR2=0.1192.     

Assembly of silver(I) coordination polymers incorporating pyromellitic acid and N-heterocyclic ligands

Five mixed ligands coordination polymers [Ag₄(apym)₂(pma)·(H₂O)₂]_n (1), {[Ag₄(dmapym)₄(pma)·(H₂O)₂]·(H₂O)₆}_n (2), [Ag₂(apyz)₂(H₂pma)·(H₂O)₄]_n (3), {[Ag₄(apyz)₂(pma)·(H₂O)₂]·(H₂O)₂}_n (4) and [Ag₄(NH₃)₈(pma)·(H₂O)₆]_n (5) (apym = 2-aminopyrimidine, dmapym = 4, 6-dimethyl-2-aminopyrimidine, apyz = 2-aminopyrazine, H₄pma = pyromellitic acid) were synthesized and characterized. For 1 and 2, as the substituents change from H to methyl, the dimensions of 1–2 decrease from three-dimension (3D) to one-dimension (1D) due to the steric effect of methyl groups. For 3 and 4, as the ratios of Ag₂O/apyz/pma vary from 1:1:1 to 2:1:1, the structure of 3 is a 1D ladder structure built from Ag-apyz double chains and pma anions, while the structure of 4 is a two-dimension (2D) grid. As excess ammonia is added to above four reaction systems, the structure of 5 contains unprecedented {[Ag(NH₃)₂]⁺}_n chains and pma anions. The substituent on the pyrimidyl ring, ratios of reactants, solvent systems and ligand isomers intensively influence the coordination environments of metal ion and the coordination modes of the carboxyl group, and thus determine the structures of the coordination polymers. The photoluminescent properties of 1–5 were also investigated.     

Two second-order non-linear optical coordination polymers with noninterpenetrating honeycomb-like 2-D (6,3)-type networks

Two isostructural metal–organic frameworks, [ML(H₂O)₄]_n (M = Y(II) (1) and Nd(II) (2)), NaH₂L = 5-sulfoisophthalic monosodium salt), have been synthesized by hydrothermal reactions. Each metal is nine-coordinate with a distorted tricapped trigonal prismatic arrangement. L^3? is a μ³ bridge to generate a homometallic 2-D noninterpenetrating (6,3) honeycomb-like topological network structure. The luminescence spectra indicate emission maxima at 406 and 402 nm, respectively. Compounds 1 and 2 show second-harmonic generation responses that are 0.5 and 0.8 times that of urea, respectively.     

Synthesis of 2-D graphite-like and 3-D diamond-like silver(I) polymers with 1,3-imidazolidine-2-thione

Two metal–organic coordination polymers, [Ag₂(imdt)₃(OAc)₂] _n (1) (imdt = 1,3-imidazolidine-2-thione, OAc = CH₃COO^?) and [Ag(imdt)Cl] _n (2), were synthesized under similar conditions by using Et₃N (triethylamine) as buffering agent. X-ray diffraction shows that 1 crystallizes in the monoclinic system, C2 /c space group, a = 13.822(5) Å, b = 9.082(3) Å, c = 16.965(6) Å, V = 2114.2(14) ų, Z = 8, D _c = 2.012 g cm^?3. Compound 2 crystallizes in the orthorhombic system, P2₁2₁2₁ space group, a = 7.993(6) Å, b = 7.993(6) Å, c = 10.548(7) Å, V = 673.9(7) ų, Z = 4, D _c = 2.419 g cm^?3. Both 1 and 2 exhibit different architectures due to their different anions. Compound 1 shows a 2-D graphite-like network structure and 2 shows a 3-D diamond-like network structure.     

Assembling of a novel 3D Ag(I)-MOFs with mixed ligands tactics: Syntheses,crystal structure and catalytic degradation of nitrophenol

A novel 3D Ag(I)-MOFs, [Ag₂(H₃ddcba)(dpp)₂] (1), which features pcu (4¹²·6³) topology were successfully synthesized. Complex 1 exhibits predominant catalytic activity towards the degradation of o-nitrophenol (2-NP), m-nitrophenol (3-NP) and p-nitrophenol (4-NP) in aqueous solution.     

A 2-D dysprosium-organic complex constructed from 6,7-dihydropyrido(2,3-d)pyridazine-5,8-dione and oxalic acid: synthesis,characterization and photoluminescence

A pyridine derivative 6,7-dihydropyrido(2,3-d)pyridazine-5,8-dione (H₂PDH) and oxalic acid (H₂ox) are reacted with dysprosium oxide to develop a new 2-D dysprosium–organic complex [Dy(PDH)(ox)_0.5(H₂O)₂]. The single-crystal structure reveals that acylamino oxygens and coordinated waters develop a 3-D supramolecular network, which is composed of 2-D layers, and each 2-D layer is formed by 1-D Dy–H₂O–ox chains linked by tridentate PDH^2? ligands. The complex exhibits metal-centered luminescence with yellowish blue emission. The energy transfer mechanism and photoluminescence are also investigated.     

Syntheses, crystal structures and properties of six coordination compounds with flexible dps ligand

Six new compounds: [M(dps)(dca)₂]_∞ (1, M = Cd; 2, M = Fe), [Cu(dps)(dca)₂(CH₃OH)₂]_∞ (3), [M(dps)₂(SCN)₂(H₂O)₂]_∞ (4, M = Cd; 5, M = Fe), [Cu(dps)₄(SCN)₂]_∞ (6), (dps = 4,4′-dipyridyl sulfide, dca = dicyanamide) were synthesized, characterized by FT-IR, element analysis and TG. Their structures were determined by single crystal X-ray diffraction. According to the structure analysis, compounds 1 and 2 are three-dimensional microporous frameworks constructed by Cu-dps-Cu and Cu-dca-Cu bridges; compound 3 shows a zigzag chain constructed by a Cu-dps-Cu bridge; compounds 4 and 5 show double-stranded chains constructed by a Cu-(dps)₂-Cu bridge while thiocyanate anions act as terminal groups; compound 6 is a mononuclear compound. Moreover, compound 1 shows visible yellow luminescence under UV light irradiation and such phenomenon is mainly attributed to inter-ligand transitions.     

2-D metalloporphyrin coordination network of cobalt-meso-tetra(4-carboxyphenyl)porphyrin

A new metalloporphyrin coordination framework [Co(H₃TCPP)] (H₆TCPP = meso-tetra(4-carboxyphenyl)porphyrin) has been synthesized hydrothermally. Single-crystal X-ray analysis revealed it exhibits a 2-D layered coordination network structure. Hydrogen bonds are observed between carboxyl groups within the 2-D layer as well as from adjacent layers. The UV–Vis diffuse reflectance spectrum indicates the presence of the expected B (410 nm) and Q (540 and 690 nm) absorption bands. The fluorescence spectrum shows four emission bands centered at 648 nm.     

Two three-dimensional silver(I) coordination architectures with pyridine-3,5-dicarboxylate: Luminescence and structural dependence on preparing conditions

The hydrothermal reactions of pyridine-3,5-dicarboxylic acid (H₂pydc) with AgNO₃ in the mixed solvent of acetonitrile and water with different ratios lead to the formation of two three-dimensional network complexes, [Ag₅(pydc)₂(CN)]_n (1) and {[Ag₄(pydc)₂]CH₃CN}_n (2), which have been characterized by IR, single-crystal X-ray diffraction and thermogravimetric analyses. It has been demonstrated that the ratio of acetonitrile and water have great effect on the structures of products. The high ratio of acetonitrile and water is favorable for the formation of complex 1, while the low volume ratio is propitious to complex 2. The luminescent properties of complex 1 and 2 have been further investigated, and show that the luminescence intensity of 2 is much stronger than that of 1 probably due to the direct metal-metal interactions and a larger HOMO-LUMO gap in complex 2.     

Two new 2-D coordination polymers based on a purine-containing carboxylate

A purine-containing multifunctional ligand, 2-(6-oxo-6H-purin-1(9H)-yl)acetic acid (HL), and two new 2-D coordination polymers, [Co(L)₂(H₂O)₂] _n?·?2nH₂O (1) and [Ni(L)₂(H₂O)₂] _n?·?2nH₂O (2), were synthesized and characterized. Polymers 1 and 2 have isomorphous structures with (4,4)-connected topologies composed of left- and right-handed metal–organic helices sharing common metal centers. Two helical conformations in the same net are stabilized by strong π–π stacking interactions between purine groups. Through direct and water-mediated interlayer hydrogen-bond interactions those layers are assembled into stable 3-D supermolecules where slight differences in the strength of hydrogen bonds and coordination bonds result in their decomposition behaviors.     

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.     

Metal-organic coordination architectures of azole heterocycle ligands bearing acetic acid groups: Synthesis, structure and magnetic properties

Four new coordination complexes with azole heterocycle ligands bearing acetic acid groups, [Co(L¹)₂]_n (1), [CuL¹N₃]_n (2), [Cu(L²)₂·0.5C₂H₅OH·H₂O]_n (3) and [Co(L²)₂]_n (4) (here, HL¹=1H-imidazole-1-yl-acetic acid, HL²=1H-benzimidazole-1-yl-acetic acid) have been synthesized and structurally characterized. Single-crystal structure analysis shows that 3 and 4 are 2D complexes with 4⁴-sql topologies, while another 2D complex 1 has a (4³)₂(4⁶)-kgd topology. And 2 is a 3D complex composed dinuclear μ_1,1-bridging azido Cu^II entities with distorted rutile topology. The magnetic properties of 1 and 2 have been studied.     

Cobalt(II), silver(I), and lead(II) tetrabromoterephthalates exhibiting the 1-D linear chain, 2-D CdCl2-type layer,and 3-D penta-nodal mixed-connecting coordination frameworks

Reaction of tetrabromoterephthalic acid (H₂TBTA) with Co(OAc)₂, AgNO₃, or Pb(OAc)₂ under similar conditions affords three new coordination polymers {[Co(TBTA)(DMF)₂(H₂O)₂](DMF)₂}_n (1), [Ag(TBTA)_0.5]_n (2), and [Pb₂(TBTA)_1.5(OH)(DMF)]_n (3). All these complexes have been characterized by elemental analysis, IR, powder X-ray diffraction, and TG-DTA techniques. Single-crystal X-ray diffraction reveals that complex 1 has a 1-D neutral coordination array in which the adjacent Co^II centers are bridged by the TBTA spacers, whereas 2 displays a binodal CdCl₂-type coordination layer in which the Ag^I ions and TBTA ligands function as 3- and 6-connected nodes, respectively. In the structure of 3, two types of Pb^II ions are interconnected via the μ₄- and μ₅-TBTA ligands as well as the μ₃-hydroxyl ions to generate a complicated 3-D penta-nodal coordination framework with (3,4,5)-connectivity. These results clearly suggest that the metal centers with distinct binding tendencies are responsible for the remarkable structural diversity of such crystalline materials.     

Novel coordination behavior of a pteridine-benzoylhydrazone ligand (BZLMH): Theoretical calculations, XRD structures and luminescence studies

The XRD structure and the influence of the conformation in the molecular orbitals of the pteridine-benzoylhydrazone ligand (BZLMH = benzoylhydrazone of 6-acetyl-1,3,7-trimethyllumazine, lumazine = (1H,3H)-pteridin-2,4-dione) have been studied. Complexes of BZLMH with nickel(II), zinc(II) and mercury(II) have been prepared and spectroscopically characterized by IR, NMR and fluorescence spectroscopy; also XRD studies have allowed to establish two different coordinative patterns in the complexes [Ni₃(BZLMH)₃(OH)(H₂O)(CH₃CN)₂](ClO₄)₅ · 2H₂O · CH₃CN (2) and [Zn(NO₃)(BZLMH)(H₂O)](NO₃) (3). Compound (2) is a trinuclear hydroxo-centered complex with a central hydroxo group bridging the three nickel(II) ions. The [Ni₃(μ₃-OH)]⁵⁺ core is planar with the benzoylhydrazone ligands coordinated in the bis-bidentate [O(4),N(5)]-[N(61),O(63)] mode. The zinc(II) compound displays a BPT coordination geometry in which the BZLMH ligand acts in a tridentate fashion using N(5), N(61) and O(63) donor atoms. Fluorescence spectroscopic properties of benzoylhydrazone (BZLMH) are studied and the fluorescence band shift and changes in intensity is modulated by complexation with different metal ions (Ni²⁺, Zn²⁺ and Hg²⁺), so the binding is signaled such a possible cause.     

Assembly of three 3-D MOFs from 2-phenyl-4,5-imidazole dicarboxylate and oxalate

Three lanthanide–organic polymers, {[Ln(μ ₃-HPhIDC)(μ ₂-C₂O₄)_0.5(H₂O)]?·?2H₂O} _n (Ln?=?Nd (1), Sm (2), and Tb (3)), have been isolated from the reaction of 2-phenyl-1H-imidazole-4,5-dicarboxylic acid (H₃PhIDC) with equal amount of Ln(III) salts under solvothermal condition with the rigid coligand oxalate. The three polymers, which are isomorphous and isostructural, have been structurally characterized by elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction. Each exhibits a 3-D framework constructed from infinite 2-D layers joined by μ ₂-C₂O₄, which are composed of μ ₃-HPhIDC^2? and trivalent lanthanide. Thermal properties have also been investigated.