Copper Coordination Polymers Research Articles

Systematic and non-systematic substituent effects gleaned from studies on CuTCNQFn (n = 0, 1, 2, 4): Electrocrystallisation and characterisation of CuTCNQF

Exploitation of ligand substituent effects provides a method for systematically tuning the properties of inorganic compounds. Thus, fluorination of TCNQ (TCNQ = 7,7,8,8-tetracyanoquinodimethane) followed by reduction to their anionic and dianionic forms allows a series of copper(I) coordination polymers to be prepared that vary systematically with respect to redox and other properties. However, the catalytic properties of CuTCNQFn (n = 0, 1, 2, 4) do not vary systematically with the extent of fluorination as revealed by combining data obtained in this study using TCNQF and TCNQF2 with that published with TCNQ and TCNQF4. Initial studies confirmed that the cyclic voltammetry of 8.0 mM TCNQF0 (TCNQF0 = 2-fluoro-7,7,8,8-tetracyanoquinodimethane) displays two ideal one-electron reversible diffusion controlled TCNQF0/1− and TCNQF1−/2− processes at a glassy carbon electrode in acetonitrile (0.1 M Bu4NPF6). Upon introduction of equimolar [Cu(MeCN)4]+, a series of new processes involving oxidation and reduction of surface confined electrocrystallised Cu+-TCNQF1− as well as a Cu+-TCNQF2− derivative were detected. Mechanisms for the electrocrystallisation of kinetically and thermodynamically favoured phases of CuTCNQF are proposed. Variable morphology of elecrocrystallised TCNQF-based material onto ITO electrodes was evident from SEM images. CuTCNQF in the thermodynamically favoured phase was also synthesised chemically by reaction of TCNQF with copper(I) iodide or copper foil or via the reaction between TCNQF1− generated by bulk electrolysis in MeCN (0.10 M Bu4NPF6 and a stoichiometric amount of [Cu(MeCN)4]+. The catalytic activity of CuTCNQF and CuTCNQF2, formed on the surface of a copper foil, with respect to the [Fe(CN)6]3−/S2O32− aqueous redox reaction was investigated by analysis of spectrophotometric and open circuit potential measurements. Comparison with published data with CuTCNQ-Cu foil and CuTCNQF4-Cu foil revealed that the extent of catalysis achieved in these materials were similar and slow. In contrast, reaction rates in the presence of the CuTCNQF2 and CuTCNQF4-Cu foil analogues were much faster, but also similar to each other. This non-systematic effect implies that catalysis requires the TCNQ(Fn)2− (reduced dianion) to be accessible, thus the reversible potential for neither the Cu-TCNQFn1−/2− (n = 0, 1) are sufficient to achieve substantial catalysis while the reversible potential for both the Cu-TCNQFn1−/2− (n = 2, 4) reactions are well in excess of the minimum value required to achieve catalysis. The conductivity of CuTCNQF was 1.86 × 10−5 S cm−1 which is at the low end of the semiconductor range, and hence orders of magnitude less than for the kinetically favoured phase of CuTCNQ; 0.2 S cm−1. Interestingly, the fluorinated analogues of the readily accessible, highly conducting (kinetically favoured) CuTCNQ phase I are only detected transiently under voltammetric conditions for CuTCNQFn (n = 1, 2) and have not been detected for the CuTCNQF4 derivative.

Temperature-induced structural transformations accompanied by changes in magnetic properties of two copper coordination polymers

Two ferromagnetic copper compounds have been synthesized under different temperature, which represented the rare example of structural transformations resulting from the coordination modes of organic ligands supported by magnetic results.

One-pot concomitant preparation of two copper(II) coordination polymers with different configurations of bridging bithiophene ligands.

By employing the conjugated bithiophene ligand 5,5'-bis(1H-imidazol-1-yl)-2,2'-bithiophene (bibp), which can exhibit trans and cis conformations, two different CuII coordination polymers, namely, poly[[μ-5,5'-bis(1H-imidazol-1-yl)-2,2'-bithiophene-κ2N:N'](μ2-4,4'-oxydibenzoato-κ2O:O')copper(II)], [Cu(C14H8O5)(C14H10N4S2)]n or [Cu(bibp)(oba)]n, (I), and catena-poly[μ-aqua-bis[μ-5,5'-bis(1H-imidazol-1-yl)-2,2'-bithiophene-κ2N:N']bis(μ3-4,4'-oxydibenzoato)-κ3O:O':O'';κ4O:O',O'':O'-dicopper(II)], [Cu2(C14H8O5)2(C14H10N4S2)(H2O)]n or [Cu2(bibp)(oba)2(H2O)]n, (II), have been prepared through one-pot concomitant crystallization and characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis, powder X-ray diffraction (PXRD) and thermogravimetric (TG) analysis. Single-crystal X-ray diffraction indicates that the most interesting aspect of the structure is the existence of sole trans and cis conformations of the bibp ligand in a single net of (I) and (II), respectively. Compound (I) displays a threefold interpenetrating three-dimensional framework with a 4-connected {65.8} cds topology, whereas (II) features a one-dimensional chain structure. In the crystal of (II), the polymeric chains are further extended through C-H...O hydrogen bonds and C-H...π interactions into a three-dimensional supramolecular architecture. In addition, strong intramolecular O-H...O hydrogen bonds formed between the bridging water molecules and the carboxylate O atoms improve the stability of the framework of (II). Furthermore, solid-state UV-Vis spectroscopy experiments show that compounds (I) and (II) exhibit optical band gaps which are characteristic for optical semiconductors, with values of 2.70 and 2.26 eV, respectively.

Synthesis, characterization, and catecholase mimic activity of a new 1D Cu(II) polymer constructed from iminodiacetate

In this work, we report the synthesis of one-dimensional copper(II) coordination polymer [Cu(ida)(H2O)2]n (1) (H2ida = iminodiacetic acid). The polymer is characterized by different spectroscopic techniques (FTIR, EPR, UV-visible, luminescence, TGA, and PXRD) along with the single crystal X-ray diffraction analysis (SCXRD). The SCXRD study shows that 1 crystallizes in an orthorhombic system with the Pbca space group and adopts a distorted octahedral coordination geometry. 1 possesses a 1D chain structure further packed into 2D supramolecular architectures by O⋯H interactions. The FTIR spectrum of 1 ascertains the binding modes of the ligands. The EPR spectral analysis shows an isotropic signal at g = 2.09, indicating a Jahn—Teller distortion of the Cu2+ (d9) ion. Further, 1 exhibits a catecholase-like activity in methanol. It can easily oxidize the 3,5-di-tert-butylcatechol (3,5-DTBC) substrate to its respective quinone. The polymer shows a significant catalytic activity with Kcat = 214.66 h–1.

Structures and properties of three new homobinuclear nanosized supramolecular copper coordination polymers derived from carboxylate type ligands and benzimidazole

Three new homobinuclear nanosized supramolecular copper coordination polymers are hydrothermally synthesized by self-assembly reaction of L-tyrosine (Tyr), terephthalic acid (H2bdc), pyromellitic acid (H4btec) and benzimidazole (Hbzim) with copper chloride salt to generate with formula [[Cu2(tyr)2(bzim)2(Cl)2(H2O)2]]n 1, [[Cu2(bdc)2(bzim)2(H2O)6].3H2O]n 2 and [Cu2(H2btec)(bzim)(H2O)6].2H2O]n 3, which have been investigated by elemental analysis, molar conductivity and magnetic measurements, FT-IR and UV-Vis spectroscopy, (TGA/DTA) thermal analysis and X-ray powder diffraction(XRPD) analysis as well as MM2 theoretical calculations. The magnetic moment and electronic spectra of the complexes are certainly indicating the octahedral geometries. Thermal analysis of the complexes confirms the suggested structures and thermal stability. The results of the XRPD analysis and the average nanosized values of the complexes have nanosized supramolecular polymers in the triclinic system. The MM2 theoretical calculations are supported by the proposed structures.

Polymorphs of a copper coordination compound: interlinking active sites enhance the electrocatalytic activity of the coordination polymer compared to the coordination complex

A copper coordination polymer exhibits highly enhanced HER activity in neutral medium compared to a coordination complex with a similar coordination environment.

Hirshfeld surface analysis and fingerprint plots in determining the resemblance of a new copper coordination polymer synthesized by two different methods

The syntheses and crystal structure of a new copper-based coordination polymer {[Cu(2,2'-bipy)(H2O)(3,4-pydc)]·2.5H2O}n, is here described for the first time. This compound is obtained through two different synthetic methods: hydrothermal and conventional. According to the literature, different methods may result in different products. After X-ray diffraction measu­rements, it is observed that the same crystal structure was obtained. However, sometimes, even if the asymmetric unit is the same, the packing arrangement may be different, characterizing polymorphs. In order to define whether these two structures represent the same compound, the Hirshfeld surface analysis and fingerprint plots are used since they compare not only the asymmetric structure itself, but the intermolecular interactions as well. After these analyses it is stated that different synthetic methods give the same structure for the herein described coordination polymer.

Charge Redistribution Effects in Hexacyanometallates Evaluated from XPS Data

The charge redistribution effects determine the physical and functional properties of transition metal hexacyanometallates. The π‐back bonding interaction between the CN ligand and the metal (M) linked at its C end and the σ donation from the N end to a second transition metal (T), when a coordination polymer is formed, are relevant features of such effects. The π‐back donation interaction contributes to the overlapping of the electron clouds of M and T metals in the ···–T–N≡C–M–C≡N–T‐··· chain. In this contribution, we demonstrate that XPS spectroscopy is a useful tool to sense the change in the electron density redistribution in hexacyanometallates related to these two mechanisms. The results herein discussed contribute to understand the physical and chemical properties of these materials. Initially, a series of potassium salts, Kn[M6–n(CN)6] (M = CrIII, FeII, RuII, OsII, CoIII, RhIII, IrIII, PtIV) is considered in order to evaluate the role of the π‐back donation on the electron density found at the N atom, which determines the strength for the T‐NC coordination bond and of the mentioned electron clouds overlapping. Then, a representative set of transition metal (T) hexacyanometallates, T2(1‐y)K2y[FeII(CN)6], is studied in order to shed light on the electron density redistribution when a coordination bond is formed at the N end. Within such coordination polymers, the copper (2+) salts are particularly attractive by the unique interaction between the copper atom and the hexacyanometallate ion, and the potential applications of these copper (2+) complexes in heterogeneous catalysis and other areas. From these reasons, the recorded XPS spectra for Cu (2+) hexacyanometallates were evaluated in detail. In accordance with a previous study of these copper (2+) coordination polymers using other techniques, XPS data is sensing an atypical strong bonding interaction with the CN ligand. The experimental XPS data herein discussed are relevant for the coordination chemistry of transition metal hexacyanometallates and for the research community involved in their applications.

Structure, magnetism, and Congo Red dye degradation catalysis of a copper coordination polymer with a new 4,10-connected self-penetrated topology

Crystals of [Cu4(OH)2(sip)2(bpu)(H2O)4]n (1, sip = 5-sulfoisophthalate, bpu = bis(4-pyridyl)urea) were prepared by hydrothermal methods. A single-crystal structure determination showed the presence of [Cu4(OH)2(sip)2(H2O)4] kgd layer motifs bearing “butterfly” {Cu4(OH)2} tetranuclear cluster units. These are linked by sulfonate oxygen atoms and the bpu tethers into a self-penetrated 4,10-connected binodal network with an unprecedented (46)2(41251661275) topology. Variable temperature magnetic susceptibility data showed antiferromagnetic interactions within the tetrameric “butterfly” cluster units (g = 2.094(9), J1 = –8.2(3) cm−1, and J2 = –14.3(6) cm−1). Compound 1 also demonstrated utility as a heterogeneous catalyst for the UV-mediated degradation of Congo Red dye in the presence of hydrogen peroxide oxidant.

1D Copper(I) Coordination Polymer [Cu2(µ-(2,4-Cl-ba)2bn)(µ-I2)]n with a Flexible Schiff Base Ligand: Synthesis, Crystal Structure, and Thermal Stability

In this paper, bis-monodentate Schiff base ligand (2,4-Cl-ba)2bn and its 1D copper(I) coordination polymer [Cu2(μ-(2,4-Cl-ba)2bn)(μ-I2)]n are synthesized and characterized by the elemental analysis (CHN), FT-IR and 1H NMR spectroscopy. Their crystal structure is determined from the single crystal X-ray diffraction analysis. The thermal behavior of the complex is studied using thermogravimetry in order to evaluate its thermal stability and thermal decomposition pathway. The X-ray results show that the free Schiff base ligand (2,4-Cl-ba)2bn is centrosymmetric and coordinated to copper(I) ions via two iminic nitrogen atoms as a bis-monodentate bridging ligand. The coordination geometry around the copper ions is a distorted triangle formed by one nitrogen and two iodine atoms. The distance between the two symmetry-related copper atoms is very short: 2.4756(8) A.

Structural transformation of two copper coordination polymers and their enhanced benzene vapor selective detection

Two copper coordination polymers have been synthesized by using flexibly carboxylic ligand (5,5′-((1,4-phenylenebis(methylene))bis(oxy))diisophthalic acid) H4L. Structural transformations of these two coordination polymers have happened during the crystallization. By controlling the reaction time, compounds 1 and 2 can be isolated successfully, resulting in 1D and 2D structure respectively. 1D ring-like infinite chain [Cu1.5(HL)(py)2(H2O)]n·nH2O (1) was an intermediate phase during the formation of the final 2D hexagon layer [Cu2(L)(py)4(H2O)4]n·nH2O (2). To further understand the structural relationship of 1 and 2, the structural transformation between these two compounds have also been explored. Furthermore, the Quartz Crystal Microbalance (QCM) sensor modified with compound 2 has good selectivity and a high response to benzene vapor.

Polynuclear and coordination polymers of copper(II) complexes assembled by flexible polyamines and bridging rigid N-heterocyclic multicarboxylates

Four trinuclear Cu(II) complexes bridged by N-heterocyclic multicarboxylic acids: [Cu3(dien)2(μ2-Pz3,5-dc)2(H2O)2]·4H2O (1), [Cu3(pmdien)2(μ2-Py2,5-dc)2(ClO4)2(H2O)2] (2), [Cu3(trpn)2(μ2-Py2,5-dc)2(ClO4)2] (3) and [Cu3(ip3tren)2(μ2-Py2,4-dc)2(H2O)](ClO4)2 (4) and the coordination polymer: catena-[Cu2(bedmpza)2(μ2-Py2,4-dc)](ClO4)2·H2O (5) as well as the monomeric [Cu(bdmpzpy)(Py2,6-dc)]2·3H2O (6), where H3Pz3,5-dc = 3,5-pyrazole dicarboxylic acid, H2Py2,4-dc = 2,4-pyridine dicarboxylic acid, H2Py2,5-dc = 2,5-pyridine dicarboxylic acid, H2Py2,6-dc = 2,6-pyridine dicarboxylic, dien = diethylenetriamine, pmedien = N,N,N′,N″,N″-pentamethyldiethylene-triamine, bedmpza = bis(3,5-dimethylpyrazolyl-1H-ethyl)amine, trpn = tris(3-aminopropyl)amine, ip3tren = tris(2-isopropyl-2-ethyl)amine and bdmpzpy = 2,6-bis[(3,5-dimethyl-1H-pyrazolyl)methyl]pyridine were synthesized. The compounds were structurally characterized by elemental microanalyses, IR and UV–Vis spectra as well as by single crystal X-ray crystallography for 1–3, 5 and 6. In 1–3 and 5, the N-heterocyclic multicarboxylate dianion linkers are simultaneously bound by at least one N,O chelating hetero-aromatic dicarboxylato anions via ring-N atom and one O-atom of the adjacent carboxylato group and an O-atom of the carboxylates located at the other side of the heteroxyclic ring. In complex 6 the adjacent bdmpzpy ligands constitute π-π interactions through the central pyridine rings with separation of the centers of gravities = 3.666(2) Å. The degree of nuclearity in the polynuclear species depends entirely on the skeletal structure of the linker N-heterocyclic multicarboxylic acids and the amine coligands.

A facile route for the synthesis of new 1D copper(II) coordination polymer as precursors for preparation of nano structures: Crystallography and Hirshfeld surface analysis

The purpose of the present study was to investigate a simple approach for synthesis of new 1D copper (II) coordination polymer as a precursor for preparation of nano-structures based on crystallography and Hirshfeld surface analysis method. In doing so, A novel 1D copper(II) coordination polymer compound of [Cu(tp)(phen)]n(1) (tp = 1,4-benzendicarboxylic acid and phen: 1,10-Phenanthroline) was synthesized using two different methods, such as branched-tube and sonochemical methods. The X-Ray Diffraction (XRD) results revealed that with applying both methods, the produced compounds have a same crystalline phase. A Single crystal X-ray analysis of produced compound 1 using the branched-tube method showed that Cu2+ ions are 6-coordinated. The contribution of intermolecular interactions in compound 1 were studied by Hirshfeld Surface Analysis method. The role of sonication power, reaction time, concentrations of reactants, temperature on the growth and final morphology of the obtained nanostructures were studied by the sonochemical method. While, the concentrations of reactants and reaction time directly affected the final size of nano-structures of compound 1, the sonication power and temperature showed an inverse impact. Compound 1 was used as a new precursors for preparation of Cu(II) oxide structures via solid-state thermal decomposition process. The nano-structures of compound 1 were further analyzed by IR spectroscopy, powder X-ray diffraction (PXRD) and Scanning Electron Microscopy (SEM).

A copper(II) zig-zag metal–organic coordination polymer: synthesis, crystal structure, topology study, hirshfeld surface analysis and survey different conditions on morphology of a novel nano structure [Cu(L)(SCN)(H2O)2]n.2H2O

One copper(II) coordination polymer compound [Cu(L)(SCN)(H2O)2]n.2H2O (1) where L stand for 2-pyridinecarboxylic acid, was synthesized following two different experimental methods, branch tube and sonochemical irradiation nano methods. Independently of the methodology used, the same crystalline phase is obtained for each compound. Single crystal X-ray analyses on compound 1 showed that Cu2+ ions are 6-coordinated. Additionally, H-bonds incorporate the zig-zag chains in 1 into 2D (along (1,1,0) direction) frameworks. Topological analysis shows that the compound 1 is 2C1 net. Hirshfeld surface analysis of compound 1 was studied. Also, theoretical and experimental morphology were studied. The thermal stability of compound 1 was studied by thermal gravimetric. Finally, the role of reaction time and temperature on growth and final morphology of the structures obtained by sonochemical irradiation are investigated. The results indicated that particle size was reduced with increasing sonication power, temperature, sonication time and decreasing concentration of reactant.

Facile synthesis of a luminescent copper(I) coordination polymer containing a flexible benzotriazole-based ligand: An effective catalyst for three-component azide-alkyne cycloaddition

A straightforward method for the synthesis of a new luminescent copper(I) coordination polymer (CP) containing the ligand 1,3-bis(1H-benzotriazol-1-ylmethyl)benzene (L) through a self-assembly process with copper(I) iodide is reported. The CP was characterized by infrared, NMR, UV–Vis and photoluminescence spectroscopy, high resolution mass spectrometry (ESI), elemental and thermogravimetric analyses, single-crystal and powder X-ray diffraction, and relativistic density functional theory calculations. Furthermore, this one-dimensional copper(I) benzotriazole-based coordination polymer catalyzed the three-component azide-alkyne cycloaddition reaction to obtain 1,4-disubstituted 1,2,3-triazoles in good to excellent yields (up to 95%) from organic halides, sodium azide and terminal alkynes.

Syntheses, structures, and properties of zinc(II) and copper(II) coordination polymers with imidazole-containing ligands

Abstract The reactions of Zn(NO3)2 · 6H2O/CuCl2 · 2H2O and 1,4-bis(1-imidazolyl)benzene (bib)/1,4-bis(1-imidazol-1-ylmethyl)benzene (biyb), carried out under hydrothermal conditions, produced two new coordination polymers [Zn(bib)(HCOO)2 · H2O] (1) and [Cu(biyb)Cl2] (2), respectively, which were characterized by elemental analysis, infrared spectroscopy, thermogravimetric analyses, and single-crystal X-ray diffraction. In complex 1, the ZnII centers are bridged by bib ligands to form a chain, where the adjacent chains are condensed by strong intermolecular O–H · · · O hydrogen-bonding and aromatic π-π stacking interactions to generate a 3D supramolecular structure. In 2, the CuII centers are bridged by biyb ligands to form, again, chains through C–H · · · Cl hydrogen bonds, and these adjacent chains with different orientations are joined to generate a 3D supramolecular structure.

Effect of the side-chain on the topology of coordination polymers of copper(II) with amino acids

Effect of the side-chain on the topology of coordination polymers of copper(II) with amino acids

Synthesis, structure, and catalytic properties of a copper(II) coordination polymer material constructed from 5-nitro-1,2,3-benzenetricarboxylic acid and bis(4-pyridylformyl)piperazine mixed ligands

One three-dimensional coordination polymer material, {[Cu3(nbta)2(bpfp)2(H2O)2](H2O)2}n (H3nbta = 5-nitro-1,2,3-benzenetricarboxylic acid, bpfp = bis(4-pyridylformyl)piperazine), is synthesized and structurally characterized. X-Ray structural analysis shows that the compound exhibits a three-dimensional structure featuring an unusual 3-nodal 4-connected topology. The compound is further characterized by elemental analysis, infrared spectrum, thermogravimetric analysis, and UV–vis absorption spectrum. Importantly, the compound exhibits efficient heterogeneous catalytic activity to the Knoevenagel reaction at room temperature. Moreover, the recyclability and heterogeneity of the reaction were also explored.

One‐Pot hydrothermal synthesis of 1D copper (II) coordination polymers involving in-situ decarboxylation

One-Dimensional Copper(II) coordination polymers with the formula [Cu(2-pyc)2]n.nH2O (1) (2-Hpyc: Picolinic acid) and [Cu(1,10-phen)(SO4)(H2O)2]n(2) (1,10-phen: 1,10-phenanthroline) have been co-synthesized under hydrothermal conditions in the same medium. The coordination polymers characterized by elemental analysis, FT-IR spectroscopy, TG analysis, ICP-OES, PXRD and single crystal X-ray diffraction. The compound 1 crystallizes in triclinic system, space group P-1, the compound 2 crystallizes in monoclinic system, space group C2/c. In 1, the Cu(II) ions are further joined by picolinic acid ligands, generating 1D coordination polymer running parallel to the [100] direction, while the Cu(II) ions are further joined by sulfate ligands, generating 1D coordination polymer running parallel to the [001] direction in 2. Notably, the 2-Hpyc ligand is in situ generated by decarboxylation of the 2,6-pyridinedicarboxylic (2,6-pydc) acid ligand under hydrothermal conditions. Thermal stability, luminescence and electrical conductivity properties of 1 and 2 have been investigated.

Facile Synthesis of 3-(Azol-1-yl)-1-adamantanecarboxylic Acids-New Bifunctional Angle-Shaped Building Blocks for Coordination Polymers.

For the first time, orthogonally substituted azole-carboxylate adamantane ligands were synthesized and used for preparation of coordination polymers. The angle-shaped ligands were prepared by the reaction of 1-adamantanecarboxylic acid and azoles (1H-1,2,4-triazole, 3-methyl-1H-1,2,4-triazole, 3,5-dimethyl-1H-1,2,4-triazole, 1H-tetrazole, 5-methyl-1H-tetrazole) in concentrated sulfuric acid. Variation of the solvent and substituents in azole rings allowed to prepare both 1D and 2D copper(II) and nickel(II) coordination polymers, [Cu2(trzadc)4(H2O)0.7]∙DMF∙0.3H2O, [Cu(trzadc)2(MeOH)]∙MeOH, [Ni(trzadc)2(MeOH)2] and [Cu2(mtrzadc)3(MeOH)]+NO3– (trzadc-3-(1,2,4-triazol-1-yl)-adamantane-1-carboxylic acid; mtrzadc-3-(3-methyl-1,2,4-triazol-1-yl)-adamantane-1-carboxylic acid) which were structurally characterized by single crystal X-ray diffraction. Complex [Cu(trzadc)2(MeOH)]∙MeOH was shown to act as a catalyst in the Chan-Evans-Lam arylation reaction.