Resulting Coordination Polymer Research Articles

Determination of Tetracycline Antibiotics in Milk by Solid-Phase Extraction Using a Coordination Polymer Based on Cobalt Trimesinate as a Sorbent.

The coordination polymer was obtained based on cobalt trimesinate. It was characterized by elemental analysis, IR spectroscopy, X-ray diffraction analysis and scanning electron microscopy. The polymer was studied as a sorbent for solid-phase extraction of tetracycline antibiotics. Cobalt trimesinate had a high adsorption capacity (400 mg/g). Antibiotic adsorption followed the pseudo-second-order kinetic model and the Freundlich isotherm model. The process proceeded spontaneously, as indicated by the calculated thermodynamic parameters. The resulting coordination polymer has good stability and recyclability. The possibility of using cobalt trimesinate for the determination of tetracycline in various milk samples was investigated. This work holds great promise for the development and application of a cobalt trimesinate-based coordination polymer for use in sample preparation to replace the time-consuming vacuum evaporation procedure with a relatively simple solid-phase extraction procedure.

Analytical Determination of Cephalosporin Antibiotics Using Coordination Polymer Based on Cobalt Terephthalate as a Sorbent.

In this work, a coordination polymer based on cobalt terephthalate was obtained and characterized by elemental analysis, infrared spectroscopy, X-ray diffraction analysis, and scanning electron microscopy. The coordination polymer was tested as a sorbent for the solid-phase extraction of cephalosporin antibiotics, including ceftriaxone, cefotaxime, and cefazolin, from aqueous solutions. The coordination polymer had a high adsorption capacity (520.0 mg/g). Antibiotics adsorption followed pseudo-second order kinetic model and the Freundlich isotherm model. The calculated thermodynamic parameters indicate a spontaneous process. The resulting coordination polymer has good stability and reusability. The possibility of separating the studied cephalosporins on a chromatographic column filled with a coordination polymer was shown. This work opens great prospects for the development and application of a coordination polymer based on cobalt terephthalate for the removal of cephalosporins from ambient water.

Structural characterization and antimicrobial evaluation of chromium(III) and cobalt(III) complexes with 2,2-diMe-1,3-pdta: Tuning dimensionality of coordination polymer and the water content by alkyl substitution

Hexadentate 2,2-dimethyl-1,3-propanediamine-N,N,N’,N’-tetraacetate (2,2-diMe-1,3-pdta) ligand, containing two methyl substituents at the central carbon atom of a 1,3-propanediamine, has been prepared and used for the synthesis of Na[Cr(2,2-diMe-1,3-pdta)]·3.75H2O (1) and Na[Co(2,2-diMe-1,3-pdta)]·3.88H2O (2) complexes. These complexes were characterized by IR and electronic absorption spectroscopy, and single-crystal X-ray diffraction analysis. NMR (1H and 13C) spectroscopy was additionally applied for the characterization of complex 2. Crystallographic data indicate that the two investigated crystals are isostructural and contain 2,2-diMe-1,3-pdta ligand coordinated to metal ion through 2N and 4O atoms forming an octahedral complex in which the six-membered 1,3-propanediamine chelate ring adopts a twist-boat conformation. There are four such complex anions in the symmetry independent part of the unit cell. Each complex anion is further connected to the sodium counterion(s) via the bridging carboxylate group(s). Structural changes in 2,2-diMe-1,3-pdta-Cr(III) complex stimulated solely by the presence of alkyl side groups are discussed. The present study shows that in 1,3-pdta-type complexes of Cr(III) and Co(III), the environment at coordination centre can be modified by introducing substitution in one of the carbon atoms of the diamine and the resulting difference in the subunit structure can bring about noticeable change in molecular and crystal structure. The examples illustrate the importance of the steric effect for the fine tuning of the dimensionality of the resulting coordination polymer and the water content. The antimicrobial activity of complexes 1 and 2 was evaluated against different bacterial and Candida spp., while their cytotoxic effects were tested on the normal human lung fibroblast cell line (MRC-5).

Synthesis and Characterization of Metal-Organic Polymer based on Fe(III)

In this work, a coordination polymer based on iron trinuclear acetate was synthesized. The coordination polymer was obtained in two stages. At the first stage [Fe3O(CH3CO2)6(H2O)3]·2H2O – tricyclic iron acetate was synthesized. As the dicarboxylate ligand, we chose muconic acid, which is not toxic to the body. Double bonds in its structure create additional nodes for interaction with drugs. The optimal conditions for the synthesis of a coordination polymer based on tricyclic iron acetate and muconic acid were selected: solvothermal synthesis at 78 °C, autogenous pressure and using ethanol as a solvent. The resulting coordination polymer is a nanosized mesoporous framework with a narrow pore distribution, an average radius of~1.18 nm, and a developed specific surface area of 512.1 m2/g. The composition and crystal structure of tricyclic iron acetate and a coordination polymer based on it have been confirmed by the methods of elemental and X-ray phase analysis.

Enhancement of singlet oxygen generation based on incorporation of oxoporphyrinogen (OxP) into microporous solids

Singlet oxygen, 1O2, generating compounds are highly useful for photodynamic therapy or organic oxidative transformations. In this work, the synthesis and photochemical performances for singlet oxygen generation of a range of oxoporphyrinogen-containing porous coordination polymers (OxP-PCPs) are reported. Oxoporphyrinogens, a previously unreported class of singlet oxygen generators derived from the oxidation of the antioxidant-substituted porphyrin tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)porphyrin, were converted to molecular tectons by the introduction of oligophenylene-carboxylate linkers and incorporated into porous coordination polymers using well-known oxo-Zr(IV)6 cluster chemistry. Their structures and textural properties were analyzed revealing substantial surface areas up to 650 m2 g−1 for the optimum linker length (biphenylyl). The oxoporphyrinogen precursors exhibit good quantum yields of singlet oxygen generation (up to Φ = 0.37), and a high level of activity is maintained in the resulting coordination polymers, which appear to be superior for singlet oxygen generation to the precursors and to a reported reference material. These OxP-PCP materials were applied for the selective oxidation of sulfides to sulfoxides. This work demonstrates that the excellent singlet oxygen generator oxoporphyrinogens can be successfully incorporated as porous solids and conveniently applied in heterogeneous oxidative transformations.

CRYSTAL STRUCTURE OF METAL-ORGANIC FRAMEWORKS OBTAINED FROM A HETEROMETALLIC PIVALATE COMPLEX [Li2Zn2(py)2(piv)6

In the interaction of the heterometallic complex [Li2Zn2(py)2(piv)6] (piv– is the pivalate anion, py is pyridine) with 2,5-dibromoterephthalic acid (H2Br2-bdc) or 9,10-anthracenedicarboxylic acid (H2adc), two coordination polymers [Li(DMF)(HBr2-bdc)] (1) and (Me2NH2)[Zn(Hadc) (adc)]·DMF·H2O (2) are obtained. During the synthesis, the initial tetranuclear heterometallic fragment is completely fragmentated. When the same complex interacts with nitroterephthalic acid (H2NO2-bdc), a heterometallic metal-organic framework (Me2NH2)[LiZn(NO2- bdc)2]·DMF (3) is formed. Resulting coordination polymer 3 has a three-dimensional porous structure; binuclear heterometallic carboxylate moieties {LiZn(COO)3} act as secondary building blocks.

Synthesis, crystal structure and luminescent properties of isoreticular lanthanide–organic frameworks based on a tetramethyl-substituted terphenyldicarboxylic acid

A series of 3D metal–organic frameworks derived from 2′,3′,5′,6′-tetramethyl-[1,1′:4′,1′′-terphenyl]-4,4′′-dicarboxylic acid (H2L) as organic linker and various lanthanides have been prepared. The resulting coordination polymers [Ln3L4(NO3)(DMF)x(H2O)]n (where x = 2 or 3) were characterized by elemental analysis, thermogravimetric investigations, IR and TG-FTIR spectroscopy, as well as powder X-ray diffraction measurements. The crystal structure for six of these isostructural networks based on La(III), Ce(III), Nd(III), Sm(III), Tb(III) and Dy(III) was established using single crystal X-ray crystallography. As an example, the asymmetric part of [La3L4(NO3)(DMF)3(H2O)]n consists of two deprotonated ligand molecules L2- and two La(III) ions, one of them occupying a general position with full site occupancy, while the other one has a fractional occupancy of 0.5. Investigation of the luminescence of these coordination polymers showed that compounds containing La3+, Nd3+ and Gd3+ possess only the emission associated with the anion of the organic ligand (L2-), polymers containing Eu3+ and Tb3+ show pure metal-centered radiation, while networks containing Dy3+ and Sm3+ display dual metal- and ligand-centered luminescence. The organic linker acts as a good antenna for Tb3+, Eu3+, Dy3+ and Sm3+ ions.

Electrochemically Directed Synthesis of Cobalt(II) and Nickel(II) TCNQF21–/2– Coordination Polymers: Solubility and Substituent Effects in the TCNQFn (n=0, 1, 2, 4) Series of Complexes

The reversible diffusion controlled cyclic voltammetry for the reduction of TCNQF­n0/1–/2– (where n=0, 1, 2, 4) changes significantly on addition of Co2+ and Ni2+ transition metal ions (M2+) because the kinetics associated with electrocrystallisation of the resulting coordination polymers [M(TCNQF2)2(H2O)2] and [M(TCNQF2)] are rapid on the voltammetric time scale. The voltammetry of solutions containing M2+ and TCNQF­2 was undertaken in acetonitrile (0.1M Bu4NPF6) at both GC and ITO electrodes. New one electron reduced TCNQF2 materials prepared via electrochemically directed synthesis were shown to have the formula [M(TCNQF2)2(H2O)2], assessed by vibrational (IR and Raman) spectroscopy, elemental analysis and thermogravimetric analysis. The solubility of [Ni(TCNQF2)2(H2O)2] (Ksp=8.29×10−11 M3) was significantly higher than the [Co(TCNQF2)2(H2O)2] (Ksp=1.43×10−11M3). Cyclic voltammetric data suggest the electrocrystallisation of two phases of [Ni(TCNQF2)2(H2O)2] occurs, which is not evident for [Co(TCNQF2)2(H2O)2]. Electrocrystallisation of the highly insoluble [M(TCNQF2)] was achieved at low M2+ and TCNQF2 concentrations. A comparison with published data on the voltammetry of TCNQF­n (n=0, 1, 2 and 4) for the series of TCNQF­n (n=0, 1, 2 and 4) containing M2+ is provided. An assessment of the electronic impact of the fluorine substituent of the underlying redox reactions also is established. Predictions are made for the voltammetric behaviour expected for the other transition metal cations with reduced TCNQFn derivatives.

How Does the Fluorination of the Linker Affect the Stability of Trimesate-Based Coordination Polymers and Metal–Organic Frameworks?

The syntheses and crystal structures of the monopotassium salts of difluorinated and tri/perfluorinated trimesic acid (1,3,5-benzenetricarboxylic acid ≡ H3BTC) are presented, namely, K(H2 dF-BTC) ( Fdd2, Z = 16) and K(H2 pF-BTC) ( Cc, Z = 4). For the first time, together with already known K(H2 mF-BTC), all fluorination degrees of trimesic acid are accessible and can be used for a systematic study of the influence of fluorination on the stability of the resulting coordination polymers and metal-organic frameworks (MOFs). The monopotassium salts show a decreasing (chemical) stability in water upon heating, as well as a decreasing thermal stability, as evidenced by differential scanning calorimetry/thermogravimetric analysis (DSC/TGA). A similar decreasing thermal stability is found for two series of isostructural coordination polymers (UHM-33 topology: ∞2[Cu2(L)2(DMA)2]·2DMA with L2- = H mF-BTC2- and H dF-BTC2-) and MOFs (∞3[Ba(L)(H2O)2]·1/2H2O with L2- = HBTC2-, H mF-BTC2- and H dF-BTC2-). Remarkably, while the decomposition temperatures decrease with increasing fluorination of the linker, the releasing temperatures for embedded solvent molecules (DMA and H2O, respectively) increase. To identify possible candidates for the synthesis of isostructural coordination polymers and MOFs with BTC3- ligands with different degrees of fluorination, a database-adapted approach was developed, which utilizes the increased torsion angle between the carboxylate groups and the phenyl rings in these materials as a structure-determining parameter.

Syntheses, Structures, and Catalytic Properties of Three Copper(II) Coordination Polymers Based on 2,3,5,6‐Tetrafluoro‐1,4‐bis(triazole‐ylmethyl)benzene and Benzene Carboxylate Ligands

Three new mixed‐ligand coordination polymers of CuII, namely, [Cu(Fbtx)(L1)(H2O)]n (1), [Cu(Fbtx)0.5(HL2)(H2O)2]n (2), and {[Cu(Fbtx)1.5(HL3)(H2O)]·H2O}n (3) [Fbtx = 2,3,5,6‐tetrafluoro‐1,4‐bis(1,2,4‐triazole‐1‐ylmethyl)benenze, H2L1 = terephthalic acid, H3L2 = trimesic acid, NaH2L3 = 5‐sulfoisophthalic acid monosodium salt], were hydrothermally synthesized and structurally characterized by elemental analysis, IR spectra, and single‐crystal and powder X‐ray diffraction techniques. All the complexes have a two‐dimensional (2D) coordination layer structure. Of these, 1 displays a planar 44‐sql structure whereas both 2 and 3 are highly undulated 63‐hcb nets. Moreover, their thermal stability and catalytic behaviors in the aerobic oxidation of 4‐methoxybenzyl alcohol were also investigated as well. The results indicate that the benzene dicarboxylate ligands have an effective influence on the structures and catalytic properties of the resulting coordination polymers.

Coordination polymers from dithiolato complexes and alkali metal cations: How a crystallizing and coordinating solvent influences the dimensionality

This article describes the influence of different solvents on the versatility of coordination-networks, formed from alkali metal coordination complex and transition metal bis(dithiolato) complex [M(btdt)2]1− (M = Cu(III) and Au(III); btdt = 2,1,3-benzenethiadiazole-5,6-dithiolate) in compounds 1–7: {[Na(CH3OH)4][Cu(btdt)2]}n (1), {[Na(THF)4][Cu(btdt)2]}n (2), {[Na(CH3COCH3)2][Cu(btdt)2]}n (3), {[Na(DMF)2][Cu(btdt)2]}n (4), {[Na(CH3CN)2][Cu(btdt)2]}n (5) {[Na(THF)2][Na(THF)(OH2)] [Au2(btdt)4]}n (6) and {[Na(CH3COCH3)2][Au(btdt)2]}n (7). The coordination polymers 1–5, based on copper(III)-bis(dithiolene) complex [CuIII(btdt)2]1−, are synthesized by the recrystallization of a dark-brown coloured precipitated precursor (P1) having a black appearance from the different solvents. The precursor P1 was obtained by the reaction of one mole equivalent of CuCl2·2H2O with two mole equivalents of H2btdt in MeOH, treated with an excess amount of NaOH in an open air atmosphere. For the preparation of compounds 6 and 7, AuCl3·2H2O was treated with H2btdt in MeOH containing NaOH to obtain precipitated precursor P2, which was recrystallized from THF and acetone to produce single crystals of 6 and 7 respectively. In the crystal structures of coordination polymers 1–7, where sodium coordination complex is a cationic component, the dimensionality of the networks of the resulting coordination polymers has greatly been influenced by the nature of hybridization of central carbon atom of the sodium-coordinated solvent, which happens to be the recrystallizing solvent. In order to investigate the influence of the counter cation on the structural diversity and dimensionality, we have compared the supramolecular chemistry of these sodium metal based coordination polymers 1–7 with that of our previously reported potassium-based coordination polymers {[K(CH3COCH3)3][Cu(btdt)2]}n and {[K(CH3CN)2][Cu(btdt)2]}n. All these compounds have been characterized unambiguously by single crystal X-ray crystallography and routine spectroscopy (IR, UV-visible and NMR). Interestingly, copper compounds 1 and 3–5 exhibit two quasi-reversible reduction responses at −0.13 V and −1.10 V vs Ag/AgCl respectively in DMF solutions.

Metallo-supramolecular assemblies of dinuclear Zn(II) and Mn(II) secondary building units (SBUs) and a bent silicon dicarboxylate ligand

Two metallo-supramolecular polymers {[Zn2(L)4(DMF)2]·0.8DMF}n (1) and {[Mn2L2(DMSO)4]·2DMSO}n (2) (H2L = bis(p-carboxyphenyl)diphenylsilane) have been synthetized by the reaction of Zn(NO3)2·6H2O and Mn(NO3)2·4H2O respectively, with the above mentioned acid as ligand under solvothermal conditions. Both coordination polymers were structurally characterized by single crystal X-ray diffraction, elemental analysis, FTIR and UV–Vis spectroscopy. Single crystal X-ray diffraction analysis reveals dinuclear Zn(II) and Mn(II) nodes bridged by mono or double deprotonated ligand molecules coordinated in syn-syn bidentate mode. Thermal and moisture stability and photophysical properties of the resulting coordination polymers were studied and correlated with their structure.

Coordination driven architectures based on metalloligands offering appended carboxylic acid groups

Abstract.The field of coordination polymers (CPs) has grown rapidly in the recent time and exemplifies one of the most exciting fields in the solid state and structural chemistry. In order to search for new CPs with desirable structural features and attractive functional properties, various synthetic strategies have been adopted including the challenging metalloligand approach. This approach relies on developing a metalloligand that is capable of placing the appended functional groups to limited directions thus resulting in limited structural variations—a landmark step towards predictable architectures. Consequently, a variety of metalloligands offering assorted functional groups have been developed and explored for the construction of noteworthy CPs. This perspective article summarizes an important class of metalloligands offering appended carboxylic acid groups with a focus on the design strategies to understand the architectures of the resultant CPs being controlled by the metalloligands. In addition, a concise discussion has been included about the applications of selected CPs to demonstrate their practical utilization.Graphical AbstractSYNOPSIS This perspective summarizes an important class of metalloligands offering appended carboxylic acid groups with focus on the design strategies to understand the architectures of the resultant coordination polymers being controlled by the metalloligands.

Zinc and copper complexes of stilbene iminopyridine ligands with η2-Olefin binding mode

Two stilbene based iminopyridine ligands (L1-L2) synthesized by a condensation reaction between N,N-Dimethyl-4,4′-azodianiline and 2-pyridinecarboxaldehyde or 2,6-pyridinedicarboxaldehyde, with 73% and 65% yield, are described. The two ligands have been characterized by elemental analysis and spectroscopic techniques. The complexation of ligand L1 with ZnCl2 afforded neutral tetrahedral zinc(II) metal complex C1 formulated as [ZnL1Cl2] with a 2D supramolecular architecture reinforced by π···π stacking and hydrogen bonding in the solid state. Interestingly in the case of copper(I) complex C2, ligand L1 acts as a ditopic ligand since it coordinates one Cu(I) with an iminopyridyl fragment and a second metal center with an η2-olefin binding mode giving rise to a 1D-polymeric structure. The coordination sphere is completed with an acetonitrile solvent molecule leading to a distorted tetrahedral geometry around copper cation and the resulting coordination polymer can be formulated as {[Cu(L1)2CH3CN]BF4}. In addition complexation of L2 with zinc chloride afforded complex C3 formulated as [ZnL2Cl2]. DFT and TDDFT computations permitted to investigate the frontier MOs of all species and to assign their UV–visible absorption bands.

Coordination polymers based on dithiophosphato/dithiophosphonato nickel complexes and linear 1,4-di(3-pyridyl)buta-1,3-diyne ligand

The reactions between ligand 1,4-di(3-pyridyl)buta-1,3-diyne (L) and the differently P-substituted dithiophosphato [Ni((RO)2PS2)2] [R = Me (1), Et (2)] and dithiophosphonato [Ni((4-MeOC6H4)(RO)PS2)2] [R = Me (3), Et (4)] nickel complexes have been performed, and the solid state structures of the resulting coordination polymers [1·L]∞–[4·L]∞ investigated. L acts as spacer between the complex units driving the formation of zig-zag polymeric chains. Inter-chain interactions involving the P-substituents have been discussed and the different supramolecular 3D-constructs described. The L donor ability has been confirmed also by spectrophotometric determination of the formation constants of the species 1·2L, 2·2L and 1·2L, and by theoretical studies.

Luminescent Sensing of Volatile Organic Compounds Using a Zn-based Coordination Polymer with Tunable Morphology

Here we report the mechanochemical synthesis of Zn(ADB)n coordination polymer (ADB: azobenzene 4, 4′-dicarboxilic acid) in good yield, which provides advanced over conventional route as it is simple, faster, cost-effective and reproducible. Both coordination polymers were characterized by X-ray powder diffraction (PXRD), field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and simultaneous thermal analysis. PXRD studies showed that both materials exhibited the same pattern, proving the presence of the crystalline coordination polymer core. FESEM micrograph images showed plate shape microstructures with a length of 10 µm, and a thickness in range from 14 to 21 µm, which suggested that synthetic routes affect the coordination polymer morphology. The resulting coordination polymers have low porosity with surface areas around from 1.92 to 1.25 m2 g− 1 and pore sizes in range from 0.36 to 0.61 nm for mechanochemical and room temperature stirring routes, respectively. In a preliminary fluorescent sensing study, the coordination polymer soaked with different volatile organic compounds showed noticeable shifts of the emission band in comparison with the same materials free solvent.

Anion-dependent assembly of diverse 1D–3D silver(I) coordination networks with a thioether ligand

A flexible thioether ligand, 1,3-bis(methylthiomethyl)benzene (L) has been employed to prepare supramolecular assemblies with silver salts of various anions such as NO3−, BF4−, PF6− and SbF6−. X-ray structural analysis reveals that even though the same metal ion (Ag+) and ligand (L) were used to react under the same conditions, anions have played a critical role in driving the variation of metal–ligand binding modes as well as network topologies of the resultant coordination polymers. The reaction of L with silver nitrate resulted in a 2-D coordination network 1, composed of metallomacrocycles bridged with NO3− ions. A 3-D framework 2 was observed when silver tetrafluoroborate was used. Although BF4− ions were not involved in coordinating with metal centers, the participation of water molecules led to a different metal–ligand binding mode and hence the formation of a network with higher dimension. The large, non-coordinating anion PF6− was found to be responsible for the assembly of a 2-D grid-like network 3, in which interesting 4+4 metallocycles occupied with PF6− ions were disclosed. However, the presence of a larger anion analog, SbF6− simplified the network structure to form a 1-D helical chain (4) through the coordination of solvent molecules (CH3CN) with silver(I) centers.

Selective Guest Inclusion in Oxalate-Based Iron(III) Magnetic Coordination Polymers.

The preparation and structural characterization of four novel oxalate-based iron(III) compounds of formulas {(MeNH3)2[Fe2(ox)2Cl4]·2.5H2O}n (1), K(MeNH3)[Fe(ox)Cl3(H2O)] (2), {MeNH3[Fe2(OH)(ox)2Cl2]·2H2O}n (3), and {(H3O)(MeNH3)[Fe2O(ox)2Cl2]·3H2O}n (4) (MeNH3+ = methylammonium cation and H2ox = oxalic acid) are reported here. 1 is an anionic waving chain of oxalato-bridged iron(III) ions with peripheral chloro ligands, the charge balance being ensured by methylammonium cations. 2 is a mononuclear complex with a bidentate oxalate, three terminal chloro ligands, and a coordinated water molecule achieving the six-coordination around each iron(III) ion. Its negative charge is balanced by potassium(I) and methylammonium cations. 3 and 4 are made up of oxalate-bridged and either hydroxo (3)- or oxo-bridged (4) iron(III) chiral three-dimensional (3D) networks of formulas [Fe2(OH)(ox)2Cl2]nn- (3) and [Fe2O(ox)2Cl2]n2n- (4) with methylammonium (3 and 4) and hydronium (4) as counterions. The common point these compounds share is related to their synthetic strategy, which consists of the use of mixed alkaline/alkylammonium cations as templating agents for the growth of the 1D or 3D iron(III) motifs. Interestingly, even in the presence of any given alkaline cation in the reaction solutions, the resulting coordination polymers (1, 3, and 4) exclusively contain the methylammonium cation, revealing the highly selective character of the 1D and 3D networks. Furthermore, the isolation of the very unstable compound 1 could be only achieved in the presence of the KCl salt, suggesting a probable templating effect of the potassium(I) cations. Finally, a study of the variable-temperature magnetic properties of the 3D compounds 3 and 4 showed the occurrence of weak ferromagnetic ordering due to a spin canting, the value of the critical temperature (Tc) being as high as 70 K.

Alkaline earth-based coordination polymers derived from a cyclotriphosphazene-functionalized hexacarboxylate

Combination of hexakis(4-carboxylatephenoxy)cyclotriphosphazene with alkaline earth ions of increasing ionic radii (Mg2+, Ca2+ and Ba2+) under different solvothermal conditions yielded three new coordination polymers, and their crystal structures were determined by single-crystal X-ray diffraction analysis. The magnesium compound displays a three dimensional (3D) network structure constructed from the deprotonated ligand and the secondary building block Mg(COO)4, which can be rationalized as a (4,6)-connected topological net with the Schläfli symbol of (44·62)3(49·66)2. The calcium compound consists of 1D infinite “Ca-O” inorganic chains connected by the deprotonated ligands to from a 3D framework. The barium compound exhibits a 3D framework in which 1D “Ba-O” inorganic chains are connected together by the deprotonated organic linkers. Due to the semi-rigid nature, the ligand adopts distinctly different conformations in the three compounds. The metal ions’ influence exerted on the final structure of the resulting coordination polymers is also discussed. When the radii of alkaline earth ions increases descending down the group from Mg(II) to Ba(II), the coordination number becomes larger and more versatile: from 6 in the magnesium compound, to 6,7 and 10 in the calcium compound, and to 8 and 9 in the barium compound, thus substantially influencing the resulting final framework structures. Also, the photophysical properties were investigated systematically, revealing that the three compounds are photoluminscent in the solid state at room temperature. This work demonstrates that although the multiplicity of conformation in the hexacarboxylate ligand based on the inorganic scaffold cyclotriphosphazene makes it difficult to predict how this ligand will form extended network, but provides unique opportunities for the formation of diverse inorganic-organic hybrids exhibiting rich structural topologies.

Assembly of [Tp*WS3Cu2]-Supported Coordination Polymers from Linkers with a Unique μ-Pyridyl Bridging Mode and Their Enhanced Third-Order Nonlinear Optical Performances

We have prepared a family of [WS3Cu2]-based coordination polymers with a rare μ-N type coordination by a simple one-pot assembly of [Et4N][Tp*WS3] (1) with CuCN in the presence of pyridine (py), 4,4′-bipyridine (bipy), 1,2-bis(4-pyridyl)ethane (bpea), and 2,4,6-tri(4-pyridyl)-1,3,5-triazine (tpt) at room temperature. The resulting coordination polymers [Tp*WS3Cu2(CN)(μ-py)]2·py (2·py), [Tp*WS3Cu2(CN)2Cu(μ-py)2]2·3py (3·3py), [Et4N][{Tp*WS3(CuCN)2Cu}2(CN)(μ4-bipy)] (4), [Tp*WS3Cu2(CN)(μ4-bpea)0.5]2·CH2Cl2 (5·CH2Cl2), and [Tp*WS3Cu2(CN)(μ6-tpt)1/3]2 (6) share a butterfly-shaped [Tp*WS3Cu2] motif with sizable concave to accommodate pyridyl ligands. The approximate mirror symmetry of the motif also induces the orthogonal coalignment of the pyridyl ligands, reinforcing a unique μ-type association with the Cu centers of the cluster skeleton. Such a coordination mode, though scarce in general coordination chemistry, is universal in our series with good ligand tolerance including ligand size and symmetry. In addi...