Self-assembly of three Cd(II) complexes: 0-D, 1-D,and 3-D structures based on 2-(1H-imidazol-1-methyl)-1 H-benzimidazole

Three new complexes, [Cd(L)I₂]₂ (1), {[Cd(L)I₂]?·?DMF} _n (2), and [Cd₂(L)₄(μ ₂-I)I(H₂O)] _n (3), have been obtained through self-assembly of an unsymmetrical ligand 2-(1H-imidazol-1-methyl)-1H-benzimidazole (L) with Cd(II) salts. Single-crystal X-ray diffraction shows that 1 displays a dimeric structure in which two Cd(II) ions are bridged by two bidentate bridging L. Complex 2 exhibits a 1-D chain structure (···Cd–L–Cd–L···) constructed by L bridging Cd(II) ions. In 3, the Cd(II) ions are five-connected nodes and linked by L and iodide leading to the 3-D network. Complexes 2 and 3 are synthesized maintaining the same solvents and stoichiometric ratio of metal and ligand at different reaction temperature. The different structures of the complexes indicate that the temperature plays a significant role in construction of the complexes. Luminescent properties of 1–3 have been investigated in the solid state at room temperature.     

Syntheses,crystal structures,and fluorescent properties of 2-D Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-1H-benzimidazole and 1,2,4,5-benzenetetracarboxylate ligands

Two new complexes, {[Cd(btec)_0.5(imb)(CH₃OH)]·CH₃OH}_n (1) and {[Cd(btec)_0.5(H₂btec)]·(H₂imb)·2H₂O}_n (2) (H₄btec = 1,2,4,5-benzenetetracarboxylic acid, imb = 2-(1H-imidazol-1-methyl)-1H-benzimidazole), have been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. Both complexes exhibit 2-D network structures. In 1, each 1,2,4,5-benzenetetracarboxylate links four Cd²⁺ cations, and each Cd²⁺ cation connects two 1,2,4,5-benzenetetracarboxylates, to form a 2-D layer, with the imb ligands located on each side of the 2-D layer. In 2, there are two kinds of 1,2,4,5-benzenetetracarboxylates in the structure. One kind is completely deprotonated and acts as hexadentate linkers, leading to a 2-D layer. The other kind is only doubly deprotonated and decorates each side of the 2-D layer. In 2, imb is protonated, forming (H₂imb)²⁺ cations that only cocrystallize with the negatively charged Cd coordination polymer ({[Cd(btec)_0.5(H₂btec)]^2?}_n), but does not coordinate to the Cd²⁺ cations. IR spectra, PXRD patterns, thermogravimetric analyses, and fluorescent properties of 1 and 2 have also been determined.     

Two- and three-dimensional coordination complexes constructed by 2-(1H-imidazol-1-methyl)-1H-benzimidazole: syntheses,structures, and fluorescent properties

Two new complexes, {[Zn(imb)(SO₄)]·H₂O}_n (1) and {[Cd₂(imb)₂(SO₄)₂(H₂O)]·CH₃OH}_n (2) (imb?=?2-(1H-imidazol-1-methyl)-1H-benzimidazole), have been solvothermally synthesized. Single-crystal X-ray diffraction shows that 1 displays a 2-D (4,4) network, which is further extended to a 3-D supramolecular structure by hydrogen bonding interactions. Complex 2 exhibits a 3-D framework with (3,5)-connected (4²·6)₂(4²·6⁵·8³)₂ topology. The results indicate that changing metal ions can influence the coordination modes of sulfate, and then affect the structures of the complexes. In addition, IR and UV–vis spectra, powder X-ray diffraction patterns, thermogravimetric analyses, and fluorescent properties of both complexes have been investigated.     

Syntheses,crystal structures,and fluorescent properties of two 2-D Cd(II) complexes based on 2-((1H-1,2,4-triazol-1-yl)methyl)-1H-benzimidazole and 1,2,4,5-benzenetetracarboxylate

Two complexes formulated as {[Cd(btec)_0.5(tmb)H₂O]·4H₂O}_n (1) and {[Cd(H₂btec)(tmb)(H₂O)]·2H₂O}_n (2) (H₄btec?=?1,2,4,5-benzenetetracarboxylic acid, tmb?=?2-((1H-1,2,4-triazol-1-yl)methyl)-1H-benzimidazole) have been synthesized and characterized by elemental analysis, IR, and single crystal X-ray diffraction. Single crystal X-ray diffraction shows that 1 has a 2-D layer structure in which tmb bridges and all of the carboxylates from 1,2,4,5-benzenetetracarboxylate chelate. In 2 Cd(II) ions are bridged by monodentate carboxylates leading to a 2-D layer structure with all tmb ligands coordinated monodentate to Cd(II), hanging at two sides of the layers. Complexes 1 and 2 are further extended to 3-D supramolecular structures by hydrogen bonding interactions. Luminescent properties have been investigated in the solid state at room temperature.     

Construction of Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-1H-benzimidazole and 1,4-benzenedicarboxylate

Three new Cd(II) complexes incorporating both 2-(1H-imidazol-1-methyl)-1H-benzimidazole (imb) and 1,4-benzenedicarboxylate (bdic^2?), [CdCl(bdic)_1/2(imb)₂]_n (1), {[Cd(bdic)(imb)(H₂O)]·DMF·2H₂O}_n (2), and [Cd(bdic)(imb)]·3H₂O}_n (3), have been prepared and structurally characterized by single crystal X-ray diffraction. Bdic^2? anions connect the?Cd-imb-Cd-imb?chains leading to a 2-D structure of 1. Bdic^2?(A) and bdic^2?(B) anions link the binuclear [Cd₂(imb)₂(H₂O)₂] units forming a 2-D structure of 2. Complex 3 features a 2-D structure involving supramolecular “double-layer” motifs. IR spectra and thermogravimetric curves are consistent with the results of the X-ray crystal structure analysis; 1–3 exhibit good fluorescence in the solid state at room temperature.     

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.     

Syntheses, crystal structures and properties of two 1-D cadmium(II) coordination polymers based on 1,1′-(1,3-propanediyl)bis-1H-benzimidazole

The combination of framework-builders 1,1′-(1,3-propanediyl)bis-1H-benzimidazole (pbbm), Cd(II) ion and framework-regulator ClO₄⁻ or SO₄²⁻ provides two new coordination polymers [Cd(pbbm)₂(ClO₄)₂]_n(1) and {[Cd(pbbm)SO₄(H₂O)₂]·CH₃OH}_n(2). Both of them display 1-D chain framework, but their detailed structures are clearly different from each other. 1 displays a 1-D ribbon of rings framework, 2 features an interesting infinite 1-D looped chain structure composed of two kinds of rings, the smaller 8-membered ring and the larger 20-membered ring. The antimicrobial activities of the two polymers were tested by the agar diffusion method and the results indicated that they exhibited antimicrobial activities against bacterial strands. The measurement of the non-isothermal kinetics of the thermal decomposition of 2 reveals that there are at least three steps that occur in its decomposition process.     

Syntheses,crystal structures and fluorescent properties of imidazole based mixed-ligand nickle and cadmium complexes

Four novel mixed-ligand nickle and cadmium complexes [Cd(tolu)₂(imi)₃] (1) [CdCl₂(imi)₂]_n (2), [Ni(imi)₆](tolu)₂ (3) and [Ni(mand)₂(imi)₂]·H₂O (4) (imi = imidazole, Htolu = o-toluic acid, Hmand = mandelic acid) were synthesized and isolated in solid state based on nickle and cadmium salts, imidazole and different carboxylic acids. These complexes were characterized by FT-IR, elemental analyses, thermogravimetric (TG) analyses, UV–vis, X-ray structural analyses and fluorescence spectra. Complexes 1 and 4 are neutral mixed-ligand molecules. Complex 2 exhibits a 2D chain constructed by [CdCl₂(imi)₂] units. Complex 3 possesses [Ni(imi)₆]^2- anions with uncoordinated tolulate anions. In complexes 1–4, each imidazole ligand provides one nitrogen atom for coordination. Tolulate and mandelate ligands coordinate to the metal through carboxyl oxygen or hydroxyl oxygen atoms. Plenty of intramolecular hydrogen bonds as N–H?O and O–H?O interactions are observed in these complexes. Fluorescence properties of the complexes have been deeply investigated and the result reveals that Fe³⁺ ion has the greatest effect on fluorescence intensity of complex 3. The fluorescence intensity decreases with the increase of iron concentration.     

Syntheses,structures and luminescent properties of two Zn(II) complexes of N-2-nitrobenzenesulfonyl-glycine acid

Two luminescent zinc coordination complexes [Zn₂(2-NBS-gly)₄(H₂O)₄]?·?2H₂O (1), and Zn(Im)₂(2-NBS-gly)₂ (2), (2-NBS-glyH?=?N-2-nitrobenzenesulfonyl-glycine acid, Im?=?imidazole) have been synthesized and their crystal structures determined by X-ray crystallography. The Zn(II) in 1 is a five-coordinate geometry and can be described as a slightly distorted square-pyramid; complex 2 is four-coordinate, forming a distorted tetrahedron. Through hydrogen bonding, complex 1 forms a 2-D network and complex 2 forms a zigzag chain. Fluorescent analyses show that both 1 and 2 exhibit photoluminescence in the solid state and may be potential candidates for photoactive materials.     

Synthesis,characterization, and fluorescence properties of dinuclear cadmium(II) complexes

Four dinuclear cadmium(II) complexes, [Cd₂(L¹)(μ₂-Cl)Cl₂] (1), [Cd₂(L²)(μ₂-Cl)Cl₂] (2), [Cd₂(L³)(μ₂-Cl)Cl₂] (3), and [Cd₂(L⁴)₃ClO₄] (4), where HL¹ = 4-methyl-2,6-bis(1-(2-piperidinoethyl)iminomethyl)-phenol, HL² = 4-methyl-2,6-bis(1-(2-pyrrolidinoethyl)iminomethyl)-phenol, HL³ = 4-methyl-2,6-bis(1-(2-morpholinoethyl)iminomethyl)-phenol and HL⁴ = 4-methyl-2,6-bis(cyclohexylmethyl)iminomethyl)-phenol, were synthesized. They were characterized by elemental analysis, FT-IR, UV–Vis, fluorescence and electronspray ionization mass spectroscopy. Complexes 1 and 4 were also characterized by single crystal X-ray analysis. The cadmiums atoms in 1 are linked by μ₂-chloride in a distorted square pyramidal geometry, whereas cadmium atom in 4 is in a distorted octahedral environment. The complexes show emission bands around 500 nm with excitation at 395 nm.     

Syntheses,structures, and properties of seven-coordinate calcium(II) and five-coordinate lead(II) complexes with 1-D structures

Two new 1-D heterometallic coordination polymers (CPs), {[Ca(NiL)(H₂O)₄]?·?3H₂O} _n (1) and {[Pb(NiL)(H₂O)₂]?·?3H₂O)} _n (2), have been prepared by reactions of CaCl₂ and NiL and Pb(NO₃)₂ and NiL in CH₂Cl₂–H₂O. H₂L denotes dimethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo-9,10-benzo-[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate. Single-crystal X-ray diffraction studies show that the coordination geometries around Ni(II) in both 1 and 2 are similar distorted N₄ square planar. All Ni–N bonds are short. Complex 1 has 1-D zigzag chain, while 2 shows 1-D “head-to-tail” structure. In crystals 1 and 2, 1-D CP chains were parallel-packed and 3-D supramolecular networks were formed via weak hydrogen bond interactions between aqua ligands and lattice water. The effects of water on the assemblies of the two CPs are discussed. Coordinated water plays an important role on the assembly procedure.     

Synthesis,crystal structure and fluorescence of a two-dimensional Cd(II) coordination polymer with thiocyanato and 4-methylpyridine N -oxide as bridging ligands

A two-dimensional coordination complex [Cd(μ_1,3-SCN)₂(μ₂-mpdo)] _n (mpdo?=?4-methylpyridine N-oxide) has been synthesized and structurally determined by X-ray crystallography. The complex crystallizes in the triclinic space group of Pī with a?=?8.2589(14)?Å, b?=?8.5409(14)?Å, c?=?9.7947(16)?Å, α?=?70.022(2)°, β?=?74.338(2)°, γ?=?71.530(2)°. Each Cd(II) is coordinated by four μ_1,3-SCN^? forming a zigzag chain and then two μ₂-mpdo monodentate ligands coordinate to two adjacent Cd(II) ions leading to a two-dimensional sheet structure along the ab plane, and in the c direction the sheets stack parallel through π–π interactions and giving a three-dimensional structure. The complex exhibits a strong fluorescent emission spectrum in the solid state.     

Syntheses,crystal structures,and photophysical properties of two 2-D coordination polymers

Two coordination polymers, [Mn(dipt)(m-BDC)₃] _n (1) and [Pb(mip)(1,4-NDC)] _n (2) [dipt?=?2-(2,4-dichlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, mip?=?2-(3-methoxyphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, m-BDC?=?isophthalic acid, 1,4-NDC?=?naphthalene-1,4-dicarboxylic acid], have been synthesized by hydrothermal reactions and characterized by elemental analysis, thermogravimetric analysis, infrared spectrum, and single-crystal X-ray diffraction. Single-crystal X-ray diffraction reveals that 1 and 2 have 1-D chain architecture. Complex 1 has a 2-D-layered structure constructed from C–H···O hydrogen bonds. Complex 2 has a 2-D-layered structure constructed from N–H···O hydrogen bonds and π–π interactions. TG analyses suggest 1 and 2 have excellent thermal stabilities from hydrogen bonds and π–π interactions. Mn(II) in 1 has trigonal bipyramidal geometry surrounded by three carboxylate oxygen atoms from three monodentate bridging m-BDC and two nitrogen atoms from one dipt. Pb(II) has [:PbN2O4] pentagonal bipyramidal geometry in 2. The luminescent properties for dipt, mip, 1, and 2 are also presented.     

Synthesis,crystal structures and fluorescence of cadmium(II) coordination polymers with derivatives of pyrazine-1,4-dioxide and thiocyanate as mixed-bridging ligands

Two Cd(II) coordination polymers have been synthesized with derivatives of pyrazine-1,4-dioxide and thiocyanate anion as bridging ligands and structurally determined by X-ray crystallography. Complex 1, [Cd(μ_1,3-SCN^?)₂(μ_1,6-L1)] _n (L1?=?2,5-dimethylpyrazine-1,4-dioxide), belongs to the triclinic, space group P 1 with a?=?5.7627(18)?Å, b?=?7.182(2)?Å, c?=?7.509(2)?Å, α?=?74.042(3)°, β?=?84.766(4)°, γ?=?88.162(4)°; complex 2, [Cd₂(μ_1,3-SCN^?)₄(μ₄-L2)] _n (L2?=?2,3,5,6-tetramethylpyrazine-1,4-dioxide), crystallizes in a monoclinic system with space group C2/m with a?=?10.194(4)?Å, b?=?13.491(6)?Å, c?=?8.140(3)?Å, β?=?120.372(4)°. Complex 1 shows a two-dimensional sheet structure, and in a direction the Cd(II) ions were coordinated by μ_1,3-SCN^? forming the one-dimensional chain and the L1 bridging ligand made the chains connect in the c direction leading to formation of a two-dimensional sheet on the ac plane. For 2 the one-dimensional chains in the a axis were constructed by coordination of μ_1,3-SCN^? bridging ligands with the Cd(II) ions, and in b and c directions the chains were joined by L2 bridging ligands leading to a three-dimensional structure. In 2 L2 displays a μ₄-bridging coordination mode. Both complexes exhibit strong fluorescence emission.     

Syntheses,crystal structures,and catalytic properties of dioxomolybdenum(VI) complexes with hydrazone ligands

Two new dioxomolybdenum(VI) complexes, [MoO₂L¹(CH₃OH)] (1) and [MoO₂L²(H₂O)] (2), where L¹ and L² are dianionic form of N′-(2-hydroxy-3-methoxybenzylidene)-4methoxybenzohydrazide and N′-(2-hydroxy-3methoxybenzylidene)-2-hydroxybenzohydrazide, respectively, have been synthesized and structurally characterized by spectroscopic methods and single-crystal X-ray determination. The complexes are mononuclear molybdenum(VI) compounds. Mo in each complex is octahedral. The difference in the substituent groups in the benzohydrazides leads to coordination of different solvent molecules. Crystals of the complexes are stabilized by hydrogen bonds. The complexes are effective catalysts for sulfoxidation.     

Two 1-D and 2-D cobalt(II) complexes: synthesis,crystal structures,spectroscopic and electrochemical properties

Two new cobalt(II) complexes, [Co(L³)₂]·CH₃OH·CH₃COCH₃ (1) (HL³ = 1-(2-{[(E)-3,5-dichloro-2-hydroxybenzylidene]amino}phenyl)ethanone oxime) and Co(L⁴)₂ (2) (HL⁴ = 1-(2-{[(E)-3,5-dibromo-2-hydroxybenzylidene]amino}phenyl)ethanone oxime), have been synthesized via complexation of Co(II) acetate tetrahydrate with HL¹ and HL². HL¹, HL², and their corresponding Co(II) complexes were characterized by IR, ¹H NMR spectra, as well as by elemental analysis and UV–Vis spectroscopy, respectively. The crystal structures of the complexes have been determined by single-crystal X-ray diffraction. 1 and 2 display that extensive hydrogen bonds and C–X···π bonding interactions construct the 1-D infinite chain [Co(L³)₂]·CH₃OH·CH₃COCH₃ and Co(L⁴)₂ into 2-D supramolecular frameworks. The electrochemical properties of two Co(II) complexes were also investigated by cyclic voltammetry.     

Syntheses,structures, and fluorescent properties of four Co(II) coordination polymers based on 5-hydroxyisophthalic acid and structurally related bis(benzimidazole) ligands

Four cobalt(II) coordination polymers, {[Co(HO-BDC)(bbp)]}_n (1), {[Co(HO-BDC)(bmbp)₂]·(H₂O)₂}_n (2), {[Co(HO-BDC)(bbb)]}_n (3), and {[Co₂(HO-BDC)₂(bmbb)₂]·(H₂O)₃}_n (4), where HO-H₂BDC?=?5-hydroxyisophthalic acid, bbp = 1,3-bis(benzimidazol-1-yl)propane, bmbp = 1,3-bis(2-methyl-benzimidazol-1-yl)propane, bbb = 1,4-bis(benzimidazol-1-yl)butane, and bmbb = 1,4-bis(2-methyl-benzimidazol-1-yl)butane, have been synthesized and characterized by elemental analyses, IR spectra, single-crystal X-ray diffraction, thermogravimetric analyses, and fluorescence properties. Compounds 1 and 3 are 4-connected 2-D networks with (4⁴·6²) topology. Compound 2 is a 1-D chain, while 4 features a 1-D ladder. These 1-D and 2-D complexes are further connected by hydrogen bonds to form 3-D supramolecular architectures. Complexes 1–4 showed very strong yellow luminescence emission.     

1-D chain Cd(II) compound based on flexible phenylenediacetic ligand: synthesis,crystal structure,and fluorescent properties

A coordination polymer of Cd^II with a flexible ligand in [Cd(Hpda)₂(4,4′-bipyridyl)₂]?·?(H₂O)₂ (1) (H₂pda?=?1,2-phenylenediacetic acid) has been synthesized by hydrothermal reactions and characterized by IR, TG, fluorescent spectrum, X-ray powder diffraction, and single-crystal X-ray diffraction techniques. The results show that 1 is monoclinic, with space group P2(1)/c, a?=?1.1704(7), b?=?1.7206(1), and c?=?2.2073(1) nm, β?=?120.881(2)°. In 1, the Cd(II) ions are linked by 4,4′-bipyridyl ligands to form 1-D chain with the arms of 1,2-pda ligands. These chains are imbedded into each other to form 2-D supramolecular sheets through hydrogen bonds. Adjacent 2-D sheets are assembled to 3-D network architecture through the crystallization of water molecules. Photoluminescence properties of 1 were investigated in the solid state at room temperature. The spectrum shows intense photoluminescence at 300?nm (λ_ex?=?275?nm).     

Syntheses,crystal structures,and photophysical properties of two 2-D coordination polymers with different geometries of lead(II)

Two complexes constructed from aromatic acid and N-heterocyclic ligands have been synthesized by hydrothermal reaction: [Pb(cipt)(NDC)]_n (1) [cipt?=?2-(3-chlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, NDC?=?naphthalene-1,4-dicarboxylic acid] and [Pb(ipm)(BDC)₂]_n (2) [BDC?=?terephthalic acid, ipm?=?5-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-2-methoxyphenol]. Single-crystal X-ray analysis shows that 1 exhibits an interesting arm-shaped chain structure. 1-D ladder chain structure is formed by N–H···O bonding interactions and further into a 2-D network by N–H···O hydrogen bonds and interchain π–π stacking interactions. Complex 2 shows a 2-D butterfly wings structure, which has been rarely reported. The structure in 2 has intermolecular N–H···O interactions, which help in construction of the 3-D framework. In 1, the coordination sphere of Pb(II) is hemi-directed, whereas the Pb(II) geometry in 2 is holo-directed. The solid-state fluorescence spectra of 1 and 2 are also investigated, as well as the ligands cipt and ipm.     

Syntheses,structures and properties of two Cu complexes with 4-(1H-imidazol-4-ylmethyl)aminophthalic acid

Two temperature-dependent copper(II) complexes {[Cu(HL)][Cu(HL)(H₂O)]} _n (1) and {[Cu(HL)]·H₂O} _n (2) [H₃L = 4-(1H-imidazol-4-ylmethyl)aminophthalic acid] have been synthesised under hydrothermal conditions. X-ray diffraction analysis reveals that complex 1 displays two crystallographic independent units, 1D chain and binuclear unit, respectively. The 1D chains and binuclear molecules are staggered arrangements along the c-axis in an (…ABAB…) fashion. When increasing the reaction temperature, complex 2 was obtained with only 1D chains structure. In addition, the magnetic property of complex 2 was studied, which indicates antiferromagnetic interactions between the neighbouring Cu(II) centres. The electrochemical and electrocatalytic properties of complex 2 have also been studied by modified glassy carbon electrode of 2.