Coordination Polymer Networks Research Articles

Formation of tannic acid-calcium polymeric network in pore solution: Characterization and kinetics

This study investigates the changes of tannic acid (TA) at varying concentrations in cement pore solution. Interestingly, TA spontaneously forms nanosheet tannic acid-calcium polymeric networks (TA-Ca) by interacting with Ca2+. Spectral, thermal, ionic and organic carbon analyses determine the composition and structural characteristics of these networks and detail the formation mechanism. The networks are connected via hydrogen bonding, C–C coupling and complexation. Moreover, network composition, structure and formation are closely dependent on TA concentration. At low concentrations, crystalline coordination polymer networks form, following second-order kinetics (key factor: Ca2+ concentration). At high concentrations, amorphous C–C coupled polymer networks form, following first-order kinetics (key factor: catalytic oxidation of Ca2+). This study aims to elucidate the reaction and mechanism of TA in cement paste, providing a novel theoretical basis for applying renewable bio-admixtures in sustainable construction.

Poly[[μ-1,3-bis-(pyridin-3-yl)urea]bis-(μ4-glutarato)dicopper(II)

The title compound, [Cu2(C5H6O4)2(C11H10N4O)]n, contains square-pyramidally coordinated CuII ions linked by anti-gauche conformation glutarate (glu) ligands into [Cu2(glu)2]n di-periodic coordination polymer layers with embedded [Cu2(OCO)4] paddlewheel clusters. In turn, the layer motifs are connected by 1,3-di(pyridin-3-yl)urea (3-dpu) linkers to form a [Cu2(glu)2(3-dpu)]n tri-periodic coordination polymer network. Treating the [Cu2(OCO)4] clusters as 6-connected nodes reveals an underlying 41263 pcu topology according to TOPOSPRO software [Blatov et al. (2014 ▸). Cryst. Growth Des. 14, 3576-3586].

A cobalt-coordination polymer as a highly selective and sensitive luminescent sensor for detecting 2,4,6-trinitrophenol

In this paper, a new three-dimensional network coordination polymer {[Co(TPTC)(HBPDPE)2·2H2O]·3H2O} n [[[(1:1′:4′,1″-terphenyl)-3,3″,5,5″-tetracarboxylic cobalt (II)] dipyridine dihydrate] trihydrate] (Complex 1) was generated under solvothermal synthesis by rigid conjugated ligand H4TPTC ([1:1′:4′,1″-terphengl]-3,3″,5,5″-tetracarboxylic), V-shaped BPDPE (4,4′-bis (pyridyl) diphenyl ether) and Co(II) ion. In complex 1, the neighboring Co(II) ions are linked by deprotonated TPTC4- to achieve a 1D zigzag chain [Co(TPTC)(HBPDPE)2] n , then the adjacent [Co(TPTC)(HBPDPE)2] n chains linked each other by various H-bondings to extend the structure from 1D chain to 3D network. Complex 1 has excellent fluorescence sensing performance and exhibits high sensitivity and selectivity for detecting 2,4,6-trinitrophenol (TNP), the quenching constant K sv is up to 2.08 × 105 M−1 along with the correlation coefficient R 2 of 0.993. Furthermore, the quench mechanisms of this Co-MOF as a sensor to detect nitro- aromatic explosives were studied as well.

Two new Keggin-based copper-organic complexes constructed from pyrazole derivatives: Syntheses, structures and catalytic properties

By regulating the initial reactant molar ratio, two new Keggin-based copper-organic complexes formulated as [Cu2(H2O)(L)2(HL)2](HPMo12O40)·2H2O (1) and [Cu4L4(H2O)2](H3PMo12O40) (2) (HL = 1-(4-carboxylbenzyl)-3-(pyrazine-2-yl)]pyrazole) have been synthesized triumphantly under hydrothermal conditions. Single crystal X-ray diffraction analyses show that compound 1 is a 3D supramolecular structure constructed by 1D metal–organic chains [Cu2(H2O)(L)2(HL)2]n2n+ and PMo12 anions via hydrogen bonds. Compound 2 is a 2D [Cu2L2(H2O)]n coordination polymeric network containing left and right helical chains. By hydrogen bonding interactions between adjacent [Cu2L2(H2O)]n networks and PMo12 anions, the 2D network extends to a 3D supramolecular structure. The two compounds can not only photocatalytic degrade methylene blue and Rhodamine B, but also have electrocatalytic reduction of H2O2, BrO3- and NO2– and oxidation of ascorbic acid. Moreover, their electrochemical sensing properties have also been studied. These results suggest compounds 1 and 2 can be used as multifunctional materials.

Study on the Coordination Effect of Different Flexible Polybenzimidazoles with Copper Ions

High-performance polymers such as polybenzimidazole (PBI) can have their thermomechanical properties greatly enhanced by the coordination of their rich imidazole groups with metal ions. The molecular chain’s flexibility influents on metal ion coordination greatly. In this paper, PBI with different chain flexibility was synthesized by varying the number of ether bond-containing monomers during the polymerization process. Rheological characterization of supramolecular networks obtained by coordination of different flexible PBI with copper ions was performed to explain in depth the effect of molecular chain flexibility on the reaction between copper ions and imidazole groups. The enhanced mechanical properties of the copper ion coordination polymer networks were compared to provide insight into the enhanced toughening mechanism of PBI with metal ion coordination.

Poly[[bis-[μ4-3-(2-carboxyl-atophen-yl)propionato]{N-[2-(pyridine-3-amido)-eth-yl]nicotinamide}-dicopper(II)] penta-hydrate

In the title compound, {[Cu2(C10H8O4)2(C14H14N4O2)]·5H2O}n, the CuII cations are coordinated in a square-pyramidal fashion, with four 3-(2-carb-oxy-phen-yl)propionate (cpp) carboxyl-ate O-atom donors in the basal plane, along with an N-atom donor from a N-[2-(pyridin-3-yl-amino)-eth-yl]nicotinamide (pen) ligand in the apical position. [Cu2(cpp)2]n coordination polymer layer motifs with embedded {Cu2(OCO)4} paddlewheel clusters are thereby constructed. These layer motifs are connected into a three-dimensional [Cu2(cpp)2(pen)]n coordination polymer network by tethering pen ligands. Treating the {Cu2(OCO)4 paddelwheel clusters as 6-connected nodes reveals an underlying cross-pillared self-penetrated rob network with 48668 topology. The water mol-ecules of crystallization are held to the coordination polymer network by N-H⋯O and O-H⋯O hydrogen-bonding patterns.

Mussel-inspired poly(hydroxyethyl acrylate-co-itaconic acid)-catechol/hyaluronic acid drug-in-adhesive patches for transdermal delivery of ketoprofen

This research aimed to create new hydrophilic drug-in-adhesive patches for transdermal drug delivery. Poly(hydroxyethyl acrylate-co-itaconic acid)-catechol (PHI-cat) and hyaluronic acid (HA) were used as main components in the pressure-sensitive adhesive. Citric acid and aluminium hydroxide were exploited as crosslinking agents and ketoprofen was employed as a model delivering compound. The adhesive performance, physicochemical properties, drug-polymer interaction, drug crystallization, drug content, drug permeation through the skin, and coordination polymer network of the patches were investigated. In addition, skin irritation and adhesion potential in human subjects were assessed. Due to the ability of catechol groups to form interaction with the skin tissue, the patches containing PHI-cat and HA offered a considerably greater adhesion ability to human skin compared with the patches without catechol and commercial patches. Furthermore, the patches had good physical and chemical stability. Therefore, these catechol-functionalized patches may be potential transdermal drug delivery systems with excellent adhesive properties for the delivery of a drug through the skin.

Three-fluorescence sensor for minute-time scale low-cost analysis of urinary oxalate in urolithiasis metabolic assessment

Since oxalate plays an important role in the metabolic assessment of urolithiasis, there is need for convenient and efficient methods for oxalate detection. Herein, we report a three-signal fluorescence strategy for oxalate analysis based on the ability of oxalate to reduce Cu2+ to Cu+, and the ability of pyrophosphate-cerium coordination polymeric networks (PPi-Ce CPNs), cadmium telluride quantum dots (CdTe QDs), and N-Methyl Mesoporphyrin (NMM) to selectively detect Cu2+ and Cu+. The detection range was 100 nM to 1 mM, the turnaround time was 6 min, while the limits of detections for PPi-Ce CPNs, QDs and NMM as reporters were 25 nM, 10 nM and 40 nM, respectively. Visual detection of oxalate relied on color change in the solution, which could be observed using the naked eye. The fluorescent system was used for oxalate analysis in 44 urine samples (32 calcium oxalate stone patients, 12 controls without urolithiasis), and the results were consistent with clinical diagnosis and imaging data. Moreover, the visual system was used to analyze 8 urine samples (4 patients and 4 controls), and showed good consistency with clinical diagnosis and computed tomography imaging results. These findings suggest that the method has potential application for the metabolic assessment of urolithiasis.

Structural diversity and luminescence properties of M(II) complexes based on 4-carboxyphenoxybutanoic acid and N-containing ligands

4-Carboxyphenoxybutanoic acid (H2cpob) and its monosodium salt (NaHcpob) are synthesized and characterized. The crystal structure of NaHcpob shows that the sodium atoms are connected by the carboxyl group of Hcpob−, forming a three-dimensional coordination polymer network. NaHcpob reacts with metal salts and N-containing ligands produced following complexes: [Co(cpob)(H2O)2]n1, [Zn(cpob)(phen)(H2O)]22, [Cd(cpob)(phen)]n3, [Mn(cpob)(phen)·4H2O]n4, and [Cd2(cpob)2(bimb)]n5 (phen ​= ​1,10-phenanthroline, bimb ​= ​1,4-bis(imidazole-1-ylmethyl)benzene). Single-crystal X-ray diffraction analysis showed that these complexes have different metal-organic frameworks, ranging from binuclear (2) to one-dimensional (3 and 4), two-dimensional (1), and three-dimensional (5) arrangements. When only H2cpob forms a complex with metal ions, the ligand connects the metal ions into a higher-dimensional structure. In contrast, the terminal ligand (phen) added as an auxiliary ligand forms a low-dimensional complex. And when the bridging auxiliary ligand (bimb) is added, the high-dimensional complex can still be formed. The flexible conformation of H2cpob and the different N-containing ligands may be responsible for the structural diversity of binary H2cpob metal complexes. These metal complexes also displayed many differences in their fluorescence properties in the solid state.

Heterogeneous Dendrimer-Based Catalysts.

The present review compiles the advances in the dendritic catalysis within the last two decades, in particular concerning heterogeneous dendrimer-based catalysts and their and application in various processes, such as hydrogenation, oxidation, cross-coupling reactions, etc. There are considered three main approaches to the synthesis of immobilized heterogeneous dendrimer-based catalysts: (1) impregnation/adsorption on silica or carbon carriers; (2) dendrimer covalent grafting to various supports (silica, polystyrene, carbon nanotubes, porous aromatic frameworks, etc.), which may be performed in a divergent (as a gradual dendron growth on the support) or convergent way (as a grafting of whole dendrimer to the support); and (3) dendrimer cross-linking, using transition metal ions (resulting in coordination polymer networks) or bifunctional organic linkers, whose size, polarity, and rigidity define the properties of the resulted material. Additionally, magnetically separable dendritic catalysts, which can be synthesized using the three above-mentioned approaches, are also considered. Dendritic catalysts, synthesized in such ways, can be stored as powders and be easily separated from the reaction medium by filtration/centrifugation as traditional heterogeneous catalysts, maintaining efficiency as for homogeneous dendritic catalysts.

A time-resolved ratiometric luminescent anthrax biomarker nanosensor based on an Ir(III) complex-doped coordination polymer network.

Herein, an Ir(III) complex-doped coordination polymer network (Ir(III)@GMP-Eu3+) is fabricated for the first time for the ratiometric luminescent detection of the anthrax biomarker 2,6-dipicolinic acid (DPA) through the analysis of time-resolved emission spectra (TRES). The linear detection range is from 10 nM to 5 μM with a detection limit of 3.3 nM in aqueous solution. Attributed to the long lifetime of Ir(III)@GMP-Eu3+, the developed sensor exhibits an excellent DPA monitoring ability in a high-background solution through TRES.

A fluorescent and scattering dual-mode probe based on a carbon dot@cerium-guanosine monophosphate coordination polymer network for tetracycline detection.

Dual-mode sensing with a two-signal read-out is conducive to the improvement of detection accuracy. Herein, a fluorescent and scattering dual-mode chemosensor for tetracycline (TC) is proposed based on a carbon dot@cerium-guanosine monophosphate (CD@GMP-Ce) coordination polymer network. The inexpensive CD@GMP-Ce was prepared by exploiting the adaptive inclusion capability of coordination polymers and possessed remarkable fluorescence and strong Rayleigh scattering. The functional CD@GMP-Ce demonstrated fluorescence and scattering, the two optical-signal responses to TC simultaneously. Based on TC-specific fluorescence and scattering decline, the dual-mode detection of TC was established and the probe's detection limits were 43 nM in the fluorescence mode and 77 nM in the scattering mode, respectively. Furthermore, the potential application of the dual-mode sensor was verified by measuring TC in milk and tap-water samples. The study not only provides a new perspective for the development of assay methods for TC but also expands the applications of cerium coordination polymers.

Hydrogen-bonded 3D like structures of Cu(II)/Zn(II) coordination polymers: photoluminescence, TDDFT study and semiconductive properties

Two Cu/Zn complexes [Cu(4,4'-bipy)(H2O)2(ClO4)2] nn(4,4'-bipy) (1) and [Zn(4,4'-bipy)(H2O)4]3 n 6n(4,4'-bipy)6n(ClO4)·2nH2O (2) (4,4'-bipy = 4,4'-bipyridine) have been prepared via hydrothermal reactions and characterized by single-crystal X-ray diffraction. Both complexes feature an infinite 1-D chain-like structural motif with the metal ions surrounded by two nitrogen atoms and four oxygen atoms to yield a octahedral configuration. Both complexes have a 3-D coordination polymer network formed by the rich hydrogen-bonding interactions. Powder photoluminescence studies reveal that they have an emission in the blue (1) or red (2) region of the light spectrum. Time-dependent density functional theory investigation discover that the nature of the emission is resulted from the ligand-to-metal charge transfer for 1, as well as ligand-to-ligand charge transfer for 2. Narrow optical band gaps of 1.43 eV (1) and 2.24 eV (2) are found by the solid-state UV/vis diffuse reflectance spectra.

Encapsulating Ru(bpy)32+ in an infinite coordination polymer network: Towards a solid-state electrochemiluminescence sensing platform for histamine to evaluate fish product quality

In this work, we demonstrate a novel solid-state electrochemiluminescence (ECL) sensor based on the Ru(bpy)32+@terbium-guanosine monophosphate infinite coordination polymer network ((Ru(bpy)32+@Tb-GMP ICPn). Comparing with the traditional luminescence of Ru(bpy)32+ observed in a liquid system, the proposed method of encapsulating Ru(bpy)32+ into ICPn for immobilization greatly improves the ECL signal and efficiency, which is attributed to the unique porous structure and large specific surface area of ICPn. Moreover, the solid-state Ru(bpy)32+ ECL sensor has good biocompatibility and low toxicity. Taking histamine (HA) as a detection model, a good linear relationship between ECL intensity and logarithm of HA concentration was obtained with a low detection limit of 17 nM, and satisfactory results were obtained for detecting HA levels in fish samples as well. The proposed solid-state Ru(bpy)32+ ECL sensor has great application prospects in the safety of food.

A One‐Pot Synthesis of “K(hfa) glyme” Adducts: Effect of the Polyether Length on the Ion Coordination Sphere

AbstractPotassium complexes are starting to gather more and more interest from academia and industry because of their intriguing application possibilities. Novel adducts of potassium hexafluoroacetylacetonato [K(hfa)] with polyethers (monoglyme, diglyme, triglyme, and tetraglyme) were synthesized through a single step reaction and characterized through FT‐IR spectroscopy as well as 1H and 13C NMR spectroscopy. Single crystal X‐ray diffraction studies enabled the identification of fascinating K coordination polymeric networks.

Quantitative principal component analysis of multiple metal ions with lanthanide coordination polymer networks

Approaches oriented toward multi-target analysis are of practical value in obtaining comprehensive information. Herein, discrimination and quantification of multiple metal ions are achieved with fluorescent lanthanide coordination polymer networks (Ln-CPNs) and principal component analysis (PCA). By self-assembly of poly-phosphates (pyrophosphate, PPi or tripolyphosphate, STPP) and cerium ion (Ce3+), two Ln-CPNs are synthesized and emit intense fluorescence due to the ligand field effects of PPi and STPP on Ce3+. Relying on the coordination between poly-phosphates and various metal ions, additional metal ions may compete with Ce3+ for PPi or STPP, forming metal ion-doped Ln-CPNs and adjusting ligand field effect, which subsequently results in the variation of fluorescence intensity. The changes in fluorescence are further processed with PCA and presented with two principal component factors (PC1 and PC2). Accordingly, 14 lanthanide and 12 transition/post-transition metal ions can be evidently identified. Meanwhile, Cu2+ and Ag+ can be accurately quantified depending on relations between dominant PC1 and concentrations of metal ions. Moreover, the fluorescence-PCA sensor is employed to evaluate the composition of Eu3+/Tb3+ and Fe3+/Fe2+ pairs in their mixtures, manifesting its superiority over inductively coupled plasma-atomic emission spectroscopy. Therefore, this work provides an alternative perspective of developing nanomaterials-based fluorescence sensor for multi-target analysis.

Multisite Coordination Ligands on Cyclotriphosphazene Core for the Assembly of Metal Clusters and Porous Coordination Polymers

AbstractIn this review, we account the recent advancements on cyclotriphosphazene (N3P3Cl6) based multi‐site coordination ligands for the synthesis of multi‐metallic architectures. In case of N3P3Cl6, Phosphorous centres with two chlorides use to be bonded with nitrogen [−P(Cl2)=N−]3 at alternative positions in six membered ring to provide a robust planar structure to anchor the ligand arms with wide flexibility. Cyclic P−N robust motif is renowned as the potential support for the design of multi‐site ligands originating from phosphorus centres by viable substitution of variable number of ligand units (1 to 6) consist of one or more coordination site(s) via geminal and/or non‐geminal modes. Despite these phosphorus centres are promising to support in ligand structure, occasionally involve in coordination with transition metals as well. Three of alternative nitrogen atoms in this heterocyclic core are supposed to function as Lewis base centres while the electron releasing substituents occurred to tether on phosphorus centres, also when the resultant ring size favours adequate interaction towards the transition metal ions with respect to skeletal flexibility. The ligand modes vary with respect to numbers and orientation of coordination sites, which is imperative to enrich the ligation ability. Moreover, several examples of cyclotriphosphazene core ligands consist of the spacer oxygen atom while tethering with exocyclic ligand units to incorporate more flexibility. In accordance with coordination sites on ligand framework and choice of metal, the skeletal ring nitrogen atom(s) of the cyclotriphosphazene can be involved in coordination with metal ions. Indeed, the coordination of ligands is reported to coordinate with main group, transition and lanthanide metal ions to form variety of metal clusters and porous coordination polymers. Subsequently, the geometry of homo or heterometallic complexes with respect to versatile coordination modes of metallic complexes tends to afford inherent chemical properties for specific application. In terms of exocyclic ligands, the heterocyclic units such as pyridyloxy‐, pyrazolyl‐, pyridylalkylamino‐, bipyridyl‐, 1,10‐phenanthroline, porphyrinato, hydrazide, hydrazone, Schiff's base and spirocyclic amine units attached to cyclotriphosphazene were exploited to form series of metal complexes. Similarly, the variety of metal clusters, polymeric network (1D to 3D) and porous coordination polymers have been reported on basis of cyclic core molecule substituted with ligand units, pyridyloxy‐, multi‐carboxylic, aromatic amines substituted pyridyloxy‐ and imidazole moiety involved to form variety of products.

Guest inclusion by Borromean weave coordination networks

Reaction of N,Nʺ-ethylene-1,2-diylbis(3-pyridin-3-ylurea) (L) with AgNO3 in a variety of solvents gives a total of five 2-D Borromean weave coordination polymer networks that adopt three structural types depending on the interactions to the solvent pocket. The Borromean network is of formula [Ag2(L)3](NO3)2 ·solvent where the solvent is either a cluster of water molecules, mixtures of water and acetonitrile, water and methanol or chloroform and methanol. The Borromean structure is a thermodynamic sink and under fast crystallization conditions an alternative 2 + 2 metallomacrocycle forms that can result in metallogel formation. The metallogel structure transforms into the crystalline Borromean network over time.

Syntheses, structures and magnetic behaviors of 1D and 3D µ1,5-dicyanamide bridged copper(II) coordination polymers containing a symmetrical 1,2-diamine as a chelator

Two neutral copper(II) coordination polymers, [Cu(en)(µ1,5-dca)(dca)]n (1) and [Cu3(en)2(µ1,5-dca)6]n (2) [en = 1,2-ethanediamine, dca = dicyanamide], with µ1,5-dicyanamide bridges have been isolated. X-ray structural analysis reveals that each Cu(II) center in the asymmetric unit of 1 adopts a distorted square pyramidal geometry with a CuN5 chromophore ligated through two N atoms of the symmetrical 1,2-ethanediamine (en) ligand, one nitrile N atom of a terminal dca ligand and two nitrile N atoms of the μ1,5 bridging dca ligand. 1 is an example of coordination polymer containing both μ1,5-dca and terminal dca. Adjacent copper atoms are connected by dca ligands in the μ1,5-bridging mode affording a 1D chain structure. In the crystalline state, these 1D chains are further associated through weak intermolecular NH⋯N hydrogen bonds to form a 2D sheet structure, viewed along the crystallographic b axis. The asymmetric unit of 2 contains two types of copper(II) centers (Cu1 and Cu2). Cu1 adopts a distorted square pyramidal geometry with a CuN5 chromophore coordinated through two N atoms of the bidentate ligand (en) and three nitrile N atoms of three different μ1,5 bridged dca ligands, whereas Cu2 is connected to six nitrile atoms of six different μ1,5 bridged dca ligands, resulting in a distorted octahedral geometry with a CuN6 chromophore. Adjacent copper atoms are connected by μ1,5-bridging dca ligands to form a 3D network coordination polymer structure, which contains multiple NH∙∙∙N hydrogen bonds in the crystalline state. A variable-temperature magnetic susceptibility study shows very weak antiferromagnetic interactions among the neighboring metal centers through the μ1,5-dca bridges with J = −0.12 cm−1 for complex 1 and J = −0.19 cm−1 for complex 2.

Exploring the influence of metal ions/ligands ratio for the structure of polyoxometalate-based host-guest compounds, exhibiting different magnetic phenomena

Three novel metal-organic hosts with POM guests coordination polymers, [Co(bim)4][HPMoVI10VIV4O42] (1), {[Co(bim)2(H2O)]2 [PMoVI8VIVVV3O40(VIVO)2]}·2H2O (2), and {[Ni(bim)2(H2O)]2 [PMoVI8VIVVV3O40(VIVO)2]}□8H2O (3) (bim = bis (1-imidazolyl) methane) have been successfully prepared under hydrothermal conditions. Compound 1 shows one dimensional chain with bi-capping Keggin anion [HPMoVI10VIV4O42]2- (abbreviated as PMo10V4) as guest molecule, which forms a three dimensional array by hydrogen bonds. Considering that there are a large number of free coordinating N present on the organic ligand in 1, we increased the ratio of Co2+/bim and got a new polyoxometalate-based complex 2. Compound 2 mainly consists of host two dimensional rigid MOF sheets and guest bi-capping Keggin anion [PMoVI8 VIVVV3O40(VIVO)2]4- (denoted as PMo8V6) cluster, which are covalently-linked together to form a three dimensional array. Compound 3 and 2 are isomorphic, but contains the metal ions Ni2+ instead of Co2+ and the number of free water is different. Magnetothermal studies indicate that compound 1 and 2 all have antiferromagnetic interactions. Interestingly, compound 2 represents the novel 3D host-guest coordination polymer network with a gradual and partial spin-crossover phenomenon.