Polymeric Coordination Compound Research Articles

Trimethyltin(IV) (p-fluoro-/p‑hydroxy-/p-nitro-)benzoates and their benzimidazole complexes: X-ray structures of [Me3Sn(p-NO2C6H4CO2)]n, and [Me3Sn(p-NO2C6H4CO2). bz], DFT calculations, DNA binding, and DNA cleavage studies

A series of trimethyltin(IV) carboxylates with Sn‒O bonds: [Me3Sn(p-FC6H4CO2)] (1), [Me3Sn(p-HOC6H4CO2)] (2), [Me3Sn(p-NO2C6H4CO2)]n (3), and their benzimidazole complexes with Sn‒N bond: [Me3Sn(p-FC6H4CO2).bz] (4), [Me3Sn(p-HOC6H4CO2).bz] (5), and [Me3Sn(p-NO2C6H4CO2).bz] (6) (bz = benzimidazole) have been synthesized and characterized by elemental analysis, FT-IR, 1H, 13C, 119Sn NMR, and electrospray ionization mass spectrometric (ESI-MS) studies. The crystal structures for (3) and (6) have been authenticated by X-ray diffraction. In the crystal structure, polymeric coordination compound (3) and the monocrystal system (6) have trigonal bipyramidal geometry around the Sn centre, where most electronegative atoms occupied the axial positions, and three methyl groups occupied the equatorial positions. The gas-phase tetrahedral geometries of (1) and (2), asymmetric unit (Sc-XRD) of (3), and trigonal bipyramidal geometries of (4–6) have been optimized using the B3LYP function and LanL2Z basis, and obtained ∠C-Sn-C bond angles agree with those obtained from NMR/X-ray studies. The interaction of (1–6) with calf thymus DNA (ctDNA) has been investigated by spectroscopic titrations such as UV–visible, fluorescence, and circular dichroism (CD) titrations, and calculated binding constant values found in the 104–105 M−1 range which suggest a groove binding or electrostatic interaction between complexes and ctDNA. The gel electrophoresis studies suggest that (1–6) effectively cleaved the plasmid pBR322 DNA into three bands: the supercoiled, nicked/circular, and linear structures. The intriguing biophysical findings from the study indicate that these complexes have properties that make them strong contenders for additional research as potential anti-cancer agents.

Quantum magnetism in Fe2Cu2 polymeric branched chains: insights from exactly solved Ising-Heisenberg model

The spin-1/2 Ising-Heisenberg branched chain, inspired by the magnetic structure of three isostructural polymeric coordination compounds [(Tp)2Fe2(CN)6X (bdmap)Cu2(H2O)] ⋅ H2O to be further denoted as Fe2Cu2 (Tp = tris(pyrazolyl)hydroborate, bdmapH = 1,3-bis(dimethylamino)-2-propanol, HX = acetic acid, propionic acid or trifluoroacetic acid), is rigorously studied using the transfer-matrix method. The overall ground-state phase diagram reveals three distinct phases: a quantum antiferromagnetic phase, a quantum ferrimagnetic phase and a classical ferromagnetic phase. In the zero-temperature magnetization curve, two quantum ground states are manifested as intermediate plateaus at zero and half of the saturation magnetization, while the magnetization reaches its saturated value within the classical ferromagnetic phase. The bipartite entanglement between nearest-neighbor Heisenberg spins is more pronounced in the quantum ferrimagnetic phase compared to the quantum antiferromagnetic phase due to a fully polarized nature of the Ising spins. A reasonable agreement between theoretical predictions for the spin-1/2 Ising-Heisenberg branched chain and experimental data measured for a temperature dependence of the magnetic susceptibility and a low-temperature magnetization curve suggests strong antiferromagnetic coupling between nearest-neighbor Cu2+-Cu2+ magnetic ions and moderately strong ferromagnetic coupling between nearest-neighbor Cu2+-Fe3+ magnetic ions in the polymeric compounds Fe2Cu2. A thermal entanglement between nearest-neighbor Cu2+-Cu2+ magnetic ions persists up to a relatively high threshold temperature T ≈ 224 K and undergoes a transient magnetic-field-driven strengthening.

The Sensitivity of Structure to Ionic Radius and Reaction Stoichiometry: A Crystallographic Study of Metal Coordination and Hydrogen Bonding in Barbiturate Complexes of All Five Alkali Metals Li-Cs.

A systematic study has been conducted on barbiturate complexes of all five alkali metals, Li-Cs, prepared from metal carbonates or hydroxides in an aqueous solution without other potential ligands present, varying the stoichiometric ratio of metal ion to barbituric acid (BAH). Eight polymeric coordination compounds (two each for Na, K, and Rb and one each for Li and Cs) have been characterised by single-crystal X-ray diffraction. All contain some combination of barbiturate anion BA- (necessarily in a 1:1 ratio with the metal cation M+), barbituric acid, and water. All organic species and water molecules are coordinated to the metal centres via oxygen atoms as either terminal or bridging ligands. Coordination numbers range from 4 (for the Li complex) to 8 (for the Cs complex). Extensive hydrogen bonding plays a significant role in all the crystal structures, almost all of which include pairs of N-H···O hydrogen bonds linking BA- and/or BAH components into ribbons extending in one dimension. Factors influencing the structure adopted by each compound include cation size and reaction stoichiometry as well as hydrogen bonding.

Dynamic metal-linker bonds in metal-organic frameworks.

Metal-linker bonds serve as the "glue" that binds metal ions to multitopic organic ligands in the porous materials known as metal-organic frameworks (MOFs). Despite ample evidence of bond lability in molecular and polymeric coordination compounds, the metal-linker bonds of MOFs were long assumed to be rigid and static. Given the importance of ligand fields in determining the behaviour of metal species, labile bonding in MOFs would help explain outstanding questions about MOF behaviour, while providing a design tool for controlling dynamic and stimuli-responsive optoelectronic, magnetic, catalytic, and mechanical phenomena. Here, we present emerging evidence that MOF metal-linker bonds exist in dynamic equilibria between weakly and tightly bond conformations, and that these equilibria respond to guest-host chemistry, drive phase change behavior, and exhibit size-dependence in MOF nanoparticles.

Engineering the heterogeneous photocatalytic activity of crystalline decatungstate-based coordination polymers

Four novel decatungstate-based coordination polymers were constructed, exhibiting differentiated catalytic activities due to their distinct decatungstate coordination modes.

Thin Films of a Complex Polymer Compound for the Inhibition of Iron Alloy Corrosion in a H3PO4 Solution.

The etching of iron alloy items in a H3PO4 solution is used in various human activities (gas and oil production, metalworking, transport, utilities, etc.). The etching of iron alloys is associated with significant material losses due to their corrosion. It has been found that an efficient way to prevent the corrosion of iron alloys in a H3PO4 solution involves the formation of thin complex compound films consisting of the corrosion inhibitor molecules of a triazole derivative (TrzD) on their surface. It has been shown that the protection of iron alloys with a mixture of TrzD + KNCS in a H3PO4 solution is accompanied by the formation of a thin film of coordination polymer compounds thicker than 4 nm consisting of TrzD molecules, Fe2+ cations and NCS-. The layer of the complex compound immediately adjacent to the iron alloy surface is chemisorbed on it. The efficiency of this composition as an inhibitor of iron alloy corrosion and hydrogen bulk sorption by iron alloys is determined by its ability to form a coordination polymer compound layer, as experimentally confirmed by electrochemical, AFM and XPS data. The efficiency values of inhibitor compositions 5 mM TrzD + 0.5 mM KNCS and 5 mM TrzD + 0.5 mM KNCS + 200 mM C6H12N4 at a temperature of 20 ± 1 °C are 97% and 98%, respectively. The kinetic parameters of the limiting processes of hydrogen evolution and permeation into an iron alloy in a H3PO4 solution were determined. A significant decrease in both the reaction rate of hydrogen evolution and the rate of hydrogen permeation into the iron alloy by the TrzD and its mixtures in question was noted. The inhibitor compositions 5 mM TrzD + 0.5 mM KNCS and 5 mM TrzD + 0.5 mM KNCS + 200 mM C6H12N4 decreased the total hydrogen concentration in the iron alloy up to 9.3- and 11-fold, respectively. The preservation of the iron alloy plasticity in the corrosive environment containing the inhibitor under study was determined by a decrease in the hydrogen content in the alloy bulk.

Solvent templated luminescent metal-organic frameworks for specific detection of vitamin C in aqueous media

Two novel polymeric coordination compounds of same stoichiometry [Zn(2,6-ndc)(api)]n (where H2ndc = naphthalene-2,6-dicarboxylic acid and api = 1-(3-aminopropyl)-imidazole) have been synthesized. The two compounds PUC3 and PUC4 have been separated by a different mixture of solvents, namely DMA/MeOH/H2O and DMF/MeOH/H2O, respectively, leading to a different solid-state architecture. The single crystal structural analysis of PUC3 evidenced a four-fold interpenetrated 3D framework, while PUC4 is a porous framework formed by 2D corrugated layers. Thus, the two coordination polymers are an example of supramolecular isomerism induced by the template effect of solvent and flexibility of the aminopropyl-imidazole molecule. The synthesized PUC3 and PUC4 compounds have been successfully characterized with the help of single crystal X-ray diffraction (SCXRD), PXRD, FTIR, TGA, DSC and XPS. The two MOF's, applied as sensitive and selective probes for ascorbic acid (AA) detection in aqueous phase, appeared to react only with AA and not with any of the reactive oxygen/nitrogen species (ROS/RNS) tested. The calculated quenching constant (Ksv) values, of 0.4 × 105 M−1 (PUC3) and 0.5 × 105 M−1 (PUC4), indicate strong interaction between each metal organic framework (MOFs) and AA. They disclosed an excellent detection limit of 0.032 and 0.025 μM, respectively. Moreover, fluorescence resonance energy transfer (FRET) process is proposed as quenching mechanism and validated by DFT results.

Sequential Assembly and Stabilization of Cu6S6 Octahedral Clusters in NaCl-, NiAs-, and CdI2-Related Structures and Their Utility toward Thermochromism and Multicomponent Hantzsch Reaction.

Seven new inorganic-organic coordination polymer compounds have been synthesized and their structures are determined by single-crystal structure determination. The compounds were prepared by the sequential assembly of a [Cu6(mna)6]6- moiety in the presence of a Mn salt and a secondary amine ligand. Of the seven compounds, [{Cu6(mna)6}Mn3(H2O)(H2O)1.5]·5.5H2O (I), [{Cu6(mna)6}Mn3(H2O)(Im)1.5]·3.5H2O (Ia), [{Cu6(mna)6}{Mn(BPY)(H2O)}2{Mn(H2O)4}]·2H2O (III), and [{Cu6(mna)6}{Mn(BPE)0.5(H2O)2}2{Mn(BPE)(H2O)2}] (IV) have a three-dimensional structure, whereas [{Cu6(mna)4.5(Hmna)1.5}{Mn(BPA)(H2O)2}{Mn(H2O)}]{Mn0.25(H2O)3}·7H2O (II), [{Cu6(mna)6}{Mn(4-BPDB)0.5H2O}{Mn(H2O)2}].{Mn(H2O)6}·6H2O (V), and [{Cu6(mna)4(Hmna)2}·{Mn(H2O)3}2]·(4-APY)2·6H2O (VI) have a two-dimensional structure. Some of the prepared compounds exhibit structures that closely resemble the classical inorganic structures, such as NaCl (Ia, III), NiAs (I), and CdI2 (IV and VI). The stabilization of such simple structures from the assembly of octahedral Cu6S6 clusters and different Mn species and aromatic nitrogen-containing ligands suggests the subtle interplay between the constituent reactants. The compounds were examined for the multicomponent Hantzsch reaction, which gave the product in good yields. The compounds, II and VI, on heating to 70 °C change color reversibly from pale yellow to deep red, which suggests the possible use of these compounds as thermochromic materials. The present study suggests that the Cu6S6 octahedral clusters can be assembled into structures that resemble classical inorganic structures.

Novel Zn(II) Binuclear and Ni(II) 1D Polymeric Coordination Compounds Based on Dianilineglyoxime and Dicarboxylic Acids: Synthesis and Structure

Two coordinating compounds of zinc(II) (1) [Zn2(DAnH2)2(1,3-bdc)2(DMSO)4] and nickel(II) (2) [Ni(DAnH2)(1,4-bdc)(DMF)2]n were obtained based on dianilineglyoxime (DAnH2), 1,3-benzenedicarboxylic acid (1,3-bdcH2) and 1,4-benzenedicarboxylic acid (1,4-bdcH2), where DMSO is dimethylsulfoxide and DMF is dimethylformamide. The molecular and crystalline structure of reported compounds were established by infrared spectroscopy and single crystal X-ray diffraction, and for 1, additionally, the 1H and 13C NMR spectroscopy was used. According to data, the Zn(II) molecular complex is a binuclear and the Ni(II) is a 1D polymer compound.

Supramolecular structural influences from remote functionality in coordination complexes of 4-picolylamine ligands

A series of nine cobalt(II), copper(II) and silver(I) coordination complexes of structurally similar picolylamine ligands, N-(4-picolyl)piperidine (L1) and N-(4-picolyl)morpholine (L2), have been prepared and analyzed. These consist of a dinuclear copper(II) complex [Cu2(OAc)4(L1)2] (1), tetranuclear copper(II) complexes [Cu4OCl6(L1)4]·MeCN·H2O (2) and [Cu4OCl7(L2)2 (L2H)]·2MeCN·9H2O (3), trichlorocobaltate complexes [CoCl3 (L1H)]·MeCN (4) and [CoCl3(L2H)] (5), silver coordination polymers poly-[AgL1]SbF6·0.5THF) (6), poly-[Ag(L2)]SbF6·0.5THF (7) and poly-[Ag(L1)(CO2CF3)] (9) and discrete dinuclear silver complex [Ag2(L2)2(THF)4](SbF6)2 (8). While the coordination and classical N–H···X hydrogen bonding in these species is related and largely independent of backbone functionality, differences in ligand composition dictate the d weak interactions and the supramolecular structure. In 1, 2, 4, 6 and 9 piperidine acts as a weak hydrogen bond donor, with C–H···Cl/O/F contacts mostly observed from the methylene groups adjacent to the amine. In the morpholine species 3, 5, 7 and 8 the tendency for morpholine to associate via reciprocated C–H···O interactions overrides the other crystal packing tendencies, changing both the local and extended structures. By studying both strong and weak packing interactions, this study presents a test case for the design of discrete and polymeric coordination compounds with finely tuned modes of intermolecular interaction.

Dual-responsive luminescent sensitivities of a 3D Co-CP with turn-on and ratiometric sensing toward ascorbic acid and turn-off detecting acetylacetone

By selecting the luminescent tricarboxylate ligand H3L, a novel 3D Co(II)-based coordination polymer (compound 1) with the formula [Co(HL) (bpe)] (H3L ​= ​5-(3,4-dicarboxylphenoxy) nicotic acid; bpe ​= ​1,2-bis(4-pyridyl) ethylene) has been solvothermally synthesized, which features a 2-nodal (3, 5)-connected net with the Schläfli sign of (63·69·8). Particularly, it is found that compound 1 possesses good chemical and thermal stability. Luminescence measurements indicate that this material shows rare ratiometric turn-on luminescence response toward ascorbic acid (AA). The relative luminescent intensity ratio (I362/I410) increases linearly with increasing AA concentration in the 0–25 ​μM range with detection limit of 0.68 ​μM. Compound 1 could also respond to acetylacetone through luminescence turn-off mechanism. The limit of detection is estimated to be 1.35 ​μM. Both proposed sensing systems show good sensitivity, high selectivity and excellent anti-interference performance. In addition, the possible sensing mechanisms are also elaborately investigated.

A facile approach for preparing Zr-BDC and Zr-BDC-NH2 MOFs using solvothermal method

In the last two decades, researchers have developed new compounds made of central metals that bond in coordination with organic ligands as linkers (for example, benzene-dicarboxylic acid or BDC). These compounds are called metal-organic frameworks (MOFs) which are also known as coordination polymer compounds. MOFs have large surface area and porosity so they can be used for various purposes, such as for adsorption and removal of hazardous materials of CO2 and Hg. Here, we proposed a facile solvothermal method for preparing two kinds of MOFs with Zr as a central metal, i.e. Zr-BDC and Zr-BDC-NH2. The synthesized MOFs were characterized using XRD, FTIR, SEM, TEM, and BET. The results show that both MOFs have a crystalline structure with cubic form on the surface of MOFs. Results of the FTIR analysis show the peak at 3400 1/cm that is due to the stretching of O-H bonds of both MOFs. In the Zr-BDC-NH2, peak at 1378 1/cm represents the stretching of N-H bonds in the amino benzene-dicarboxylic or terephthalic acid linker. The surface areas of Zr-BDC and Zr-BDC-NH2 MOFs are 714 and 757 m2/g, respectively. We will utilize these MOFs as a sensor for HER2 protein, a biomarker of breast cancer.

From Isostructurality to Structural Diversity of Ag(I) Coordination Complexes Formed with Imidazole Based Bipodal Ligands, and Disclosure of a Unique Topology.

Two Ag(I) complexes with 1,3-bis(imidazol-1-ylmethyl)benzene (bib) and counterions BF4− (1) and PF6− (2) were synthesized in order to check their behavior in forming molecular/crystal structures. This allows comparison with the final products of analogous syntheses performed with similar bidentate ligands containing methyl substituents on the benzene ring, namely 1,3-bis(imidazol-1-ylmethyl)-5-methylbenzene (bimb) and 1,3-bis(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (bitmb). The Ag(I) complexes obtained with the methylated ligands mentioned above form isostructural pairs of waved 1D chains or dinuclear boxes, of general formula {[Ag(bimb)]X}n and [Ag2(btmb)2]X2, respectively (X = BF4−, PF6−), under the same reaction conditions. SCXRD analyses of 1 and 2 revealed the formation of polymeric coordination compounds of formula {[Ag2(bib)3](BF4)2}n and {[Ag(bib)]PF6}n, respectively, different from those observed for bimb. The 3D coordination polymer 1 forms a unique 5,5-c net of 5,5T188 topological type, observed for the very first time for a coordination compound, with silver cations adopting a trigonal geometry, whereas 2 shows the presence of 1D single-stranded cationic helices with linear coordination of the metal centers. Interestingly, these complexes differ not only from the mentioned isostructural pairs of related Ag(I) complexes, but also from the isostructural pair of compounds obtained as the final product when reacting bib and bimb with the larger counterion CF3SO3−. Hirshfeld surface analyses indicate a higher contribution of F⋯H intermolecular contacts in 2 than in 1, with H⋯H contacts being dominant in the latter.

Crystal structure of poly[[di-aqua-tetra-μ2-cyanido-platinum(II)iron(II)] methanol 4/3-solvate]: a three-dimensional Hofmann clathrate analogue.

In the title polymeric coordination compound, {[FePt(CN)4(H2O)2]·1.33CH3OH} n , the FeII cation (site symmetry 4/mm.m) is coordinated by the N atoms of four cyanide anions (CN-) and the O atoms of two water mol-ecules, forming a nearly regular [FeN4O2] octa-hedron. According the Fe-N and Fe-O bond lengths, the FeII atom is in the high-spin state. The cyanide anions act in a bridging manner to connect the FeII and PtII atoms. The [Pt(CN)4]2- moieties (Pt with site symmetry 4/mm.m) have a perfect square-planar shape. The latter anion is located perpendicular to the FeN4 plane, thus ensuring the creation of a three-dimensional framework. The crystal structure features methanol solvent mol-ecules of which 4/3 were located per FeII cation. These solvent mol-ecules are located in hexa-gonal pores; they inter-act with coordinating water mol-ecules through weak hydrogen bonds. Other guest mol-ecules could not be modelled in a satisfactory way and their contribution to the scattering was removed by a mask procedure.

Insight into Ground-State Spin Arrangement and Bipartite Entanglement of the Polymeric Coordination Compound [Dy2cu2]N Through the Symmetric Spin-1/2 Ising-Heisenberg Orthogonal-Dimer Chain

Insight into Ground-State Spin Arrangement and Bipartite Entanglement of the Polymeric Coordination Compound [Dy2cu2]N Through the Symmetric Spin-1/2 Ising-Heisenberg Orthogonal-Dimer Chain

Enhancing the Electrocatalytic Oxygen Evolution Reaction Performance of PBA Core-Shell Nanocubes By Phosphorized WS2 Coating

As the world's population continues to grow, increasing energy consumption has raised significant demands on the availability of non-renewable fossil fuel reserves. The day is not too far when there will be an acute shortage of energy. With less dependency on fossil fuels, green energy production is the primary aim of the research community. One of the cheap and reliable energy sources is the electrochemical water-splitting (EWS) reaction. However, the oxygen evolution reaction (OER) performance needs to be improved by developing cheap and highly efficient electrocatalysts, lowering the high activation energy barrier, and boosting the EWS reaction kinetics.1 Porous coordination polymer compounds and mainly Prussian blue analogs (PBAs) receive extensive attention in electrocatalyst designing owing to their tuneable architecture.2 Overcoming structural and compositional complexity challenges, we report the successful synthesis of trimetallic core-shell PBA nanocubes. We developed a multi-component composite catalyst, Co-Co@Ni-Fe PBA@WS2, which was subsequently transformed into a porous architecture by a low-temperature gas phosphorization process. We present here a unique impressive structure of phosphorized porous woolen balls, Co-Co@Ni-Fe PBA@WS2-P.These phosphorized woolen balls exhibit a superior electrocatalytic OER performance in alkaline medium, requiring a low overpotential of only 280 mV@10 mA cm-2 with a Tafel slope value of 70 mV dec-1, and have excellent stability under the operating conditions. The work highlights the synergism between the WS2 and the core-shell structure due to the d-band electronic structure modulation and aligned arrangement of the WS2 planes. The in-situ oxidation of the transition metal phosphides during the OER process results in amorphous metal hydroxides/oxides formation, responsible for their high performance.3–5 The loose arrangement of the multi-components in the hollow frame increases the contact area between the electrolyte and the catalyst, thus, favors the rapid release of oxygen gas bubbles produced at the electrode site. Hence, the present work suggests a way to improve the electrocatalytic OER performance by utilizing the vast potential of PBA-based materials for electrocatalytic applications. References Morales-Guio, C. G., Liardet, L. & Hu, X. Oxidatively Electrodeposited Thin-Film Transition Metal (Oxy)hydroxides as Oxygen Evolution Catalysts. J. Am. Chem. Soc. 138, 8946–8957 (2016).Zakaria, M. B. & Chikyow, T. Recent advances in Prussian blue and Prussian blue analogues: synthesis and thermal treatments. Coord. Chem. Rev. 352, 328–345 (2017).Singh, B. & Indra, A. Designing Self‐Supported Metal‐Organic Framework Derived Catalysts for Electrochemical Water Splitting. Chem. – An Asian J. 15, 607–623 (2020).Jin, S. Are Metal Chalcogenides, Nitrides, and Phosphides Oxygen Evolution Catalysts or Bifunctional Catalysts? ACS Energy Lett. 2, 1937–1938 (2017).Jamesh, M.I. & Harb, M. Tuning the electronic structure of the earth-abundant electrocatalysts for oxygen evolution reaction (OER) to achieve efficient alkaline water splitting – A review. J. Energy Chem. 56, 299–342 (2021). Figure 1

A dual fluorescent sensor coordination polymer for efficient recognition of acetylacetone and Cr(VI) anions

A novel Cu(II) coordination polymer (compound 1) formulated as [Cu(HL)(bpy)]·H2O (H3L = 4-(2′,3′-Dicarboxylphenoxy) benzoic acid, bpy = 2,2′-bipyridine) has been successfully prepared via solvothermal methods and characterized by structural analyses. Crystallographic research reveals that compound 1 exhibits a 1D metal-carboxylate chain, which self-assembles into a final 3D supramolecular network through the interchain hydrogen bonds. Further investigation indicates that compound 1 possesses excellent chemical stability. It maintains good stability in various solvents and aqueous solution with pH range of 2–11 for two weeks. The luminescence investigations manifest that compound 1 can be used as a multi-responsive fluorescence sensor for sensing acetylacetone (Hacac), CrO42− and Cr2O72− with high selectivity, sensitivity and excellent anti-interference ability through luminescence quenching. Furthermore, the probable mechanisms of selective detection have been explored in detail.

Coordination Polymers in Dicyanamido-Cadmium(II) with Diverse Network Dimensionalities

The synthesis and structural characterization of six dicyanamido-cadmium(II) complexes are reported: catena-[Cd(μ1,3-dca)(μ1,5-dca)(3-ampy)] (1), catena-[Cd3(μ1,3,5-dca)2(μ1,5-dca)4(pyNO)2(H2O)2] (2), catena-{Cd(H2O)2(μ1,5-dca)2](2,6-lut-NO)} (3), catena-[Cd(Me2en)(μ1,5-dca)2] (4), catena-[Cd(Me4en)(μ1,5-dca)2] (5), and [Cd(1,8-damnp)2(dca)2] (6), where dca = dicyanamide anion, 3-ampy = 3-aminopyridine, pyNO = pyridine-N-oxide, 2,6-lut-NO = 2,6-lutidine-N-oxide, Me2en = N,N-dimethyl-ethylenediamine, Me4en = N,N,N′,N′-tetramethyl-ethylenediamine, and 1,8-damnp = 1,8-diaminonaphthaline. The coordination polymers have different dimensionalities: 1 and 5 form 3D networks structures; 3 and 4 form polymeric 1D chains and 1DD double chains, respectively. Ribbons of three fused polymeric chains are observed in 2. In 6, the mononuclear complex units form a hydrogen-bonded supramolecular 3D network. In the coordination polymer compounds, the dca linkers display three bonding modes: the most common μ1,5-dca and the least popular μ1,3- and μ1,3,5-dca bonding. The luminescence emission and thermal properties of the complexes were investigated.

Lithium-, Sodium-, and Potassium-ion Conduction in Polymeric and Discrete Coordination Systems

Abstract Coordination compounds have been increasingly studied as a new class of promising candidates for the matrix of ionic conducting materials because of their designability and high crystallinity. The ionic conduction of light alkali metal ions (Li+ and Na+) has been developed in polymeric coordination systems, which are commonly used under nonaqueous conditions. Recent studies have shown that discrete coordination compounds, as well as hydrated polymeric coordination compounds, can function as excellent ionic conductors even for heavier K+.

Chromous carbonates containing a square-grid layer of {Cr2(CO3)4}n4n- based on a dichromium(II,II) paddlewheel core.

Polymeric coordination compounds based on Cr2n+ paddle-wheel building blocks with non-carboxylate O,O-donor ligands chelating and bridging the Cr-Cr centers have been underexplored hitherto. This paper reports the synthesis and crystal structure of a new homo-valent chromium(ii,ii) compound, Na3HCr2(CO3)4·10H2O (1). It has a two-dimensional structure in which the paddlewheel chromium(ii,ii) units of Cr2(CO3)44- are cross-linked through the carbonate groups. The layers are stacked along the [100] direction, and Na ions fill the intra and interlayer spaces with a neighboring layer distance of about 11.3 Å. The investigation of the primary magnetic properties and theoretical studies with density functional theory (DFT) reveal the partial paramagnetic properties of compound 1 arising from the Boltzmann distribution between a ground state σ2π4δ2 with S = 0 and a low-lying excited state σ2π4δδ* with S = 1 for the Cr2(ii,ii) dimer. According to Raman spectra measurements combined with theoretical calculations, the two Raman bands in the small-wavenumber region at 335 and 297 cm-1 were assigned to the vibration of the Cr-O bonds and the band at 371 cm-1 was assigned to the stretching of the Cr-Cr quadruple bond.