Structures and fluorescent properties of picolinato zinc(II) and cadmium(II) complexes based on tridentate and tetradentate benzimidazole ligands

Five picolinato zinc(II) and cadmium(II) complexes, [Zn(ntb)(pic)]ClO₄·CH₃OH·2H₂O (1), [Zn(bbma)(pic)]NO₃·2CH₃OH (2), [Cd(ntb)(pic)]ClO₄·0.75CH₃OH·H₂O (3), [Cd₂(bbma)₂(pic)₂](ClO₄)₂ (4), and [Cd₂(bbp)(bbp_-H)(pic)₂(C₂H₅OH)]ClO₄ (5), have been synthesized, where pic is the anion of picolinic acid, ntb is tris(2-benzimidazolylmethyl)amine, bbma is bis(benzimidazol-2-yl-methyl)amine, and bbp is 2,6-bis(benzimidazol-2-yl)pyridine. All the complexes were characterized by X-ray single-crystal diffraction, elemental analysis, IR, fluorescence spectroscopy, and thermal gravimetric analysis. 1–3 are mononuclear complexes in which picolinate adopts a N,O-chelating mode. 4 is a symmetrical dinuclear complex bridged by two anti-parallel picolinates in a N,O,O-coordination mode. 5 is also a dinuclear complex in which only one picolinate is a bridge. A 1-D double chain is formed by extensive H-bonds and π–π stacking in 1, while single zigzag chains are formed in 5. Complexes 2–4 all exhibit 6³-hcb 2-D frameworks. They extend to form four-connected 6⁶-dia 3-D topological nets for 2 and 4 and five-connected 4⁶·6⁴-bnn 3-D topological nets for 3. The five complexes show emission maxima in the blue region in the solid state.     

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.     

Synthesis and structural characterization of two dimensional cadmium(II) coordination polymers

Reactions of Cd(NO₃)₂?·?4H₂O with NH₄SCN, ppz (ppz?=?piperazine) and bpa (bpa?=?bis(4-pyridyl)ethane) in CH₃OH afforded the cavity-containing rectangular grids {Cd(SCN)₂(ppz)} _n (1) and {Cd(NCS)₂(bpa)} _n (2). The ppz ligand in 1 is coordinated to the metal through both nitrogen atoms to form the 1-D zig-zag chain structure and distorted {CdN₄S₂} octahedral coordination geometry at each Cd center is completed by pairs of bidentate thiocyanato ligands. Complex 2 has the 2-D arrangement constructed through 1-D double μ(N,S) end-to-end bridging thiocyanato groups bridging Cd(II) chains interconnected through disordered bpa ligands.     

Supramolecular structures of metal complexes containing barbiturate and 1,2-bis(4-pyridyl)-ethane

This work describes the synthesis, thermal, spectroscopic properties (Raman and infrared), and crystal structures of five new supramolecular compounds [Mn(bpa)(H₂O)₄]B₂?·?4H₂O (1), [Fe(bpa)(H₂O)₄]B₂?·?4H₂O (2), [Co(bpa)(H₂O)₄]B₂?·?4H₂O (3), [Zn(bpa)(H₂O)₄]B₂?·?4H₂O (4), and Co₂mal₂bpa?·?2H₂O (5), where B is the anion of barbituric acid, bpa is 1,2-bis(4-pyridyl)-ethane, and mal is malonate ion. Compounds 1–4 are isostructural, showing covalent linear 1-D [M(bpa)(H₂O)₄]²⁺ chains, which interact by hydrogen-bonding and π-stacking interactions with barbiturate and crystallization water molecules resulting in a 3-D arrangement, belonging to Pbcn space group. Compound 5 has been obtained from the opening of the barbituric acid ring, with the formation of malonate, coordinated simultaneously to three cobalts in a 1-D chain along the c-axis, whereas bpa ligand gives rise to another 1-D chain along the a- and b-axes, resulting in a 3-D coordination polymer containing cavities. The vibrational spectra of 1–4 are also very similar; Raman spectra display two intense bands related to bpa at 1616 and 1020?cm^?1, assigned to the (ν _CC/ν _CN) and ring stretching modes, respectively. The barbiturate is also confirmed by a band at 684?cm^?1; the interesting point to be emphasized is this vibrational mode is not observed for 5, corroborating the absence of this building block in the structure.     

Synthesis,structure, and thermal properties of 3-D coordination polymers constructed from asymmetrical carboxylates

Three new coordination polymers constructed from asymmetric ligands were synthesized under hydrothermal conditions and characterized with single crystal X-ray analysis, infrared, and thermal gravimetric methods. Complex 1 exhibits a 3-D network constructed from rod-shaped secondary building units. Pyrimidine-4-carboxylic acid (bpa) was used as the starting material, but under hydrothermal conditions bpa formed 2,2′-pyrimidine-4,4′-dicarboxylic acid (bpda) in situ, which further connected with Pb. 3-D two-fold interpenetration of complex 2 was obtained by the similar method as described for 1, except that Cd(NO₃)₂ · 6H₂O was used instead of Pb(NO₃)₂ · 6H₂O to react with bpa. Complex 3 shows a three-connected 3-D network. Furthermore, the photoluminescence properties of 1 and 2 were studied.     

Copper(II), Cobalt(II), and Nickel(II) Complexes of two Novel Pyridine‐derived Macrocyclic Ligands bearing o‐ and pNitrobenzyl Pendant Groups

The pendant‐armed ligands L¹ and L² were synthesized by N‐alkylation of the four secondary amine groups of the macrocyclic precursor L using o‐nitrobenzylbromide (L¹) and p‐nitrobenzylbromide (L²). Nitrates and perchlorates of Cu^II, Ni^II and Co^II were used to synthesize the metal complexes of both ligands and the complexes were characterized by microanalysis, MS‐FAB, conductivity measurements, IR and UV‐Vis spectroscopy and magnetic studies. The crystal structures of L¹, [CuL¹](ClO₄)₂·CH₃CN·H₂O, [CuL²](ClO₄)₂·6CH₃CN, [CuL²][Cu(NO₃)₄]·5CH₃CN·0.5CH₃OH and [NiL²](ClO₄)₂·3CH₃CN·H₂O were determined by single crystal X‐ray crystallography. These structural analysis reveal the free ligand L¹, three mononuclear endomacrocyclic complexes {[CuL¹](ClO₄)₂·CH₃CN·H₂O, [CuL²](ClO₄)₂·6CH₃CN and [NiL²](ClO₄)₂·3CH₃CN·H₂O} and one binuclear complex {[CuL²][Cu(NO₃)₄]·5CH₃CN·0.5CH₃OH} in which one of the metals is in the macrocyclic framework and the other metal is outside the ligand cavity and coordinated to four nitrate ions.     

含二茂铁基的锌配合物的结构及其生物活性

合成了4个含二茂铁基的锌配合物[Zn(FcCOO)(phen)₂]ClO₄·FcCOOH (1)(FcCOO=二茂铁甲酸根,phen=1,10-邻菲咯啉),[Zn(FcCOO)(phen)₂]·ClO₄·H₂O (2),[Zn(FcCOO)(FcCOGly)(phen)]·C₂H₅OH (3)(FcCOGly=二茂铁甲酰化甘氨酸)和[Zn(FcCOGly)₂(phen)]·CH₃OH (4)。用X-射线单晶衍射测定了配合物的晶体结构。对4个配合物的生物活性进行了初步研究,发现配合物的抗菌活性与配合物的配位键强度及phen含量有一定的关系。     

Hydrothermal syntheses,crystal structures and antibacterial activities of two Cu(II) complexes with quinolones

Hydrothermal reactions of ciprofloxacin with Cu(ClO₄)₂?·?6H₂O, and ofloxacin with Cu(CH₃COO)₂?·?4H₂O, yield two metal complexes: [Cu(H-Cip)₂]?·?(ClO₄)₂?·?6H₂O (1) and [Cu(Ofl)₂?·?H₂O]?·?2H₂O (2), which were characterized by elemental analysis, IR and single crystal diffraction analyses. Compounds 1 and 2 were screened for antibacterial activities against Staphylococcus aureus, Escherichia coli, Candida albicans and pseudomonas aeruginosa.     

Synthesis and characterization of picolinato and nicotinato cobalt(II) complexes containing tris(2-benzimidazolylmethyl)amine

Two new mononuclear cobalt(II) complexes [Co(ntb)(pic)](ClO₄) · (CH₃OH)_2.35 (1) and [Co(ntb)(nic)](ClO₄) · CH₃OH (2) were synthesized and structurally characterized, where ntb is tris(2-benzimidazolylmethyl)amine, pic is the anion of picolinic acid, and nic is the anion of nicotinic acid. The X-ray analysis indicates that the Co(II) center is six-coordinate in distorted octahedral and five-coordinate in distorted trigonal bipyramidal geometry for 1 and 2, respectively. In 1, the picolinate anion coordinates to Co(II) in a bidentate μ₂-N,O chelating mode. In 2, the nicotinate anion coordinates with Co(II) through a monodentate carboxylate oxygen. 1-D chain structures were formed by intermolecular hydrogen bonds in the two complexes and π–π interactions are important for the stabilization of the structures.     

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.     

Copper(II) Complexes with N,N'‐Bis(picolinidene‐N‐oxide)‐2‐hydroxy‐1, 3‐diaminopropane: Designing Binuclear Entities and Helical Chains by Versatile Ligand

Three novel copper(II) complex [Cu₂(bpa)(μ‐PhCO₂)](ClO₄)₂ ( 1 ), [Cu₂(bpa) (μ‐pyz)](ClO₄)₂ ( 2 ), and [Cu(Hbpa)](ClO₄)₂·2CH₃CN ( 3 ) have been synthesized by the reaction of Hbpa with Cu(ClO₄)₂·6H₂O in the presence and absence of exogenous ligands (where Hbpa = N, N'‐bis(picolinidene‐N‐oxide)‐2‐hydroxy‐1, 3‐diamino‐propane). Molecular structures of these compounds have been elucidated by single crystal X‐ray diffraction. 1 and 2 are both binuclear complexes in which two copper atoms are linked by the endogenous alkoxide oxygen and the exogenous benzoate and pyrazolate ligands, respectively. 3 consists of a one‐dimensional polymeric structure, in which Hbpa functions as a bridging mode.     

Zinc(ΙΙ) complexes with 5,6-dihydro-1,4-dithiin-2,3-dicarboxylic anhydrate and different N-donors: syntheses,crystal structures,and emission properties

Two new Zn^II complexes, {[Zn(L)(phen)(H₂O)]?·?H₂O}_∞ (1) and {[Zn(L)(4bpy)(H₂O)]?·?H₂O}_∞ (2) (L?=?5,6-dihydro-1,4-dithiin-2,3-dicarboxylate, phen?=?1,10-phenanthroline, and 4bpy?=?4,4′-bipyridine), have been prepared by in situ reaction of Zn(ClO₄)₂?·?6H₂O with 5,6-dihydro-1,4-dithiin-2,3-dicarboxylic anhydrate in the presence of lithium hydroxide, together with incorporating chelating phen or bridging 4bpy as co-ligands. Their structures were determined by single-crystal X-ray diffraction. Complex 1 takes a 1-D helical structure that is further assembled into a 2-D network by O–H?···?O, C–H?···?O hydrogen bonds, and weak S?···?S interactions, and then an overall 3-D supramolecular framework was formed by π?···?π stacking interactions. Complex 2 possesses a 2-D (4,4)-layered structure. The structural difference between 1 and 2 can be attributed to the different N-donor auxiliary co-ligands. Both 1 and 2 are photoluminescent materials whose emission properties are closely related to their intrinsic structure.     

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.     

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.     

Two solvent directed zinc(II) coordination polymers with 1-D single-zigzag chain and 1-D double-zigzag chains

Two coordination polymers, {[Zn(NiL)(DMA)(H₂O)₂] (DMA)(H₂O)} _n (1) (DMA?=?N,N-dimethylacetamide) and {[Zn₂(NiL)₂(DMF)(H₂O)₄]?·?3DMF} _n (2) (DMF?=?N,N-dimethylformamide), have been prepared by reactions of Zn(NO₃)₂?·?6H₂O and NiL in CH₂Cl₂-DMA–H₂O and CH₂Cl₂-DMF–H₂O, respectively. 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 analyses reveal that coordination geometries around Ni(II) are identical with slightly distorted square planar and all Ni–N bonds are very short. Complex 1 shows 1-D zigzag chain structure, while 2 has 1-D double-zigzag chains. The chains, which are packed parallel in 1 and 2, are interconnected by lattice solvent through O–H···O and C–H···O hydrogen bonds to form 3-D supramolecular networks. We discuss solvent effects on assembly of the two coordination polymers. The results reveal that coordinated solvent has influence on the assembly procedure.     

Coordination compounds of cobalt(II), nickel(II), and copper(II) with 4-(3-hydroxyphenyl)-1,2,4-triazole: Synthesis and study

New Co(II), Ni(II), and Cu(II) complexes with 4-(3-hydroxyphenyl)-1,2,4-triazole (L) with the compositions [Co₃L₆(H₂O)₅(C₂H₅OH)](NO₃)₆ · 2H₂O · C₂H₅OH (I), [Ni₃L₆(H₂O)₆](NO₃)₆ · 2H₂O (II), and [M₃L₆(H₂O)₆](ClO₄)₆ · nH₂O (M = Co2⁺, n = 2 (III); Ni²⁺, n = 2 (IV); Cu²⁺, n = 0 (V)) are synthesized. The complexes are studied by X-ray structure analysis, X-ray diffraction analysis, UV and IR spectroscopy, and the statistical magnetic susceptibility method. All compounds have the linear trinuclear structure. Ligand L is coordinated to the metal ions by the N(1) and N(2) atoms of the heterocycle according to the bidentate bridging mode. In all compounds the coordination polyhedron of the metal atom is a distorted octahedron. The molecular and crystal structures of compound I, [Co₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IIIa), and [Ni₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IVa) are determined.     

Synthesis,crystal structures,and properties of copper(II) complexes with 2,6-bis(benzimidazol-2-yl)pyridine

Three new mononuclear copper(II) complexes, [CuL(2-fca)(CH₃OH)]ClO₄?·?CH₃OH (1), [CuL(m-nba)(CH₃OH)]ClO₄ (2), and [CuL(pic)(ClO₄)]?·?CH₃OH (3), were synthesized and structurally characterized, where L is 2,6-bis(benzimidazol-2-yl)pyridine, while 2-fca, m-nba, and pic are the anions of 2-furoic acid, m-nitrobenzoic acid, and picolinic acid, respectively. All of them were characterized by elemental analysis, infrared, UV-Vis, and X-ray crystallography. In 1 and 2, the Cu(II) resides within a distorted square-pyramidal N₃O₂ coordination sphere with three nitrogens of L, one carboxylate oxygen, and one methanol. In 3, Cu(II) is coordinated with three nitrogens of L, one nitrogen and one oxygen of picolinate, and one oxygen of perchlorate in a distorted octahedral geometry. Two molecules of 1, 2, and 3 are interacted by intermolecular hydrogen-bonding interactions and strong π–π stacking interactions to form a dinuclear structural unit. The dinuclear units are further connected by H-bonds via perchlorate or lattice methanol to form a 1-D chain for 1 and 2-D network structures for 2 and 3. Hydrogen-bonding and π–π stacking interactions are important for the stabilization of the final supramolecular structures of the three complexes.     

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.     

Syntheses and structures of three chiral complexes derived from nucleophilic addition of L-proline to di-2-pyridyl ketone

In the presence of nickel acetate, a chiral ligand, (S)-Hdphp ((S)-N-[di(2-pyridyl)-hydroxy-methyl]-proline), was synthesized in situ by nucleophilic addition of L-proline to di-2-pyridyl ketone. Based on this ligand, three chiral mononuclear complexes, {Ni[(S)-dphp](DMF)(H₂O)}(ClO₄) (1), {Ni[(S)-dphp](H₂O)₂}(ClO₄)(H₂O)_1.5 (2), and {Ni[(S)-dphp](SCN)(H₂O)} (3), have been obtained and characterized by single-crystal X-ray diffraction, elemental analyses, and infrared spectra. By virtue of charge-assisted O–H?···?O hydrogen-bonding interactions, all the complexes possess double chain structures. The double chains were connected into 2-D networks via π?···?π stacking and CH?···?π interactions in 1. For 2, O–H?···?O hydrogen-bonding interactions between free water molecules and other oxygens as well as π?···?π stacking and CH?···?π interactions extend the chains into a 3-D network. Complex 3 exhibits 3-D structure via O–H?···?S interactions.     

Three polynuclear complexes with bridging triazole ligand: crystal structures

Three polynuclear clusters, [Cu₄L₈](ClO₄)₄·4H₂O (1), [Zn₃L₆(H₂O)₆](ClO₄)₆·6H₂O (2), and [Mn₃L₆(CH₃OH)₆](ClO₄)₆·4.5H₂O (3) (L?=?4-(4-hydroxyphenyl)-1,2,4-triazole), obtained by the reactions of M(ClO₄)₂·6H₂O with L have been isolated and structurally characterized. Complex 1 featured a tetranuclear Cu(I) structure. Both 2 and 3 are linear hexapositive trimers linked by three N1,N2–1,2,4-triazole ligands to the divalent central and terminal metal ions. Furthermore, the luminescence properties of 2 were investigated at room temperature in the solid state.