Three-dimensional Coordination Polymer Research Articles

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.

5,5′-Dibenzoimidazole as building block for a new 3D Co(II) coordination polymer: A combined EPR and DFT study using UB3LYP model

A new Co(II) three-dimensional coordination polymer, [Co(L)(L′)]n (1) [where L = 5,5′-dibenzoimidazole, and L′ = doubly deprotonated terephthalic acid] has been synthesized hydro(solvo)thermally and its molecular and crystal structure have been elucidated through single crystal X-ray diffraction analysis. Each Co(II) ion displays a slightly distorted trigonal bipyramidal geometry, the apical positions being occupied by the nitrogen atoms of two symmetry-related dibenzoimidazole ligands, while the oxygen atoms from three distinct terephthalic acids are in the equatorial plane. Considering the Co2C2O6 dimeric moieties as nodes, and the ancillary ligands as connectors, the structure can be simplified as a 8-c uninodal net of the type bcu, body centered cubic, with point symbol {424·64} and vertex symbol [4·4·4·4·4·4·4·4·4·4·4·4·4(3)·4(3)·4(3)·4(3)·4(3)·4(3)·4(3)·4(3)·4(3)·4(3)·4(3)·4(3)·*·*·*·*]. The EPR spectra for 1 have been reported, showing g|| = 2.176 and g⊥ = 2.052 at RT (room temperature), and g|| = 2.172 and g⊥ = 2.060 at LNT (liquid nitrogen temperature). Finally, the electronic nature of the molecular geometry of 1 has been explored by DFT computation applying the UB3LYP/def2-TZVP level of theory, showing the energy difference between the high spin and low spin configurations.

Synthesis, Structural Features, and Catalytic Activity of an Iron(II) 3D Coordination Polymer Driven by an Ether-Bridged Pyridine-Dicarboxylate

New iron(II) three-dimensional coordination polymer (3D CP), [Fe(µ3-Hcpna)2]n (1), was assembled under hydrothermal conditions from 5-(4’-carboxyphenoxy)nicotinic acid (H2cpna) as a trifunctional organic N,O-building block. This stable microcrystalline CP was characterized by standard methods for coordination compounds in the solid state (infrared spectroscopy, elemental analysis, thermogravimetric analysis, powder and single-crystal X-ray diffraction). Structure and topology of 1 were examined and permitted an identification of a 3,6-connected framework of the rtl topological type. In addition, compound 1 acts as effective catalyst precursor for oxidative functionalization of alkanes (propane and cyclic C5−C8 alkanes) under homogeneous catalysis conditions, namely for the oxidation of saturated hydrocarbons with H2O2/H+ system to produce ketones and alcohols, and for alkane carboxylation with CO/H2O/S2O82− system to obtain carboxylic acids. The influence of an acid promoter and substrate scope (propane and cyclic C5−C8 alkanes) were investigated.

Crystal Structures and Melting Behaviors of 2D and 3D Anionic Coordination Polymers Containing Organometallic Ionic Liquid Components.

Although coordination polymers generally do not melt, several that do melt have been synthesized recently and have drawn much attention. In this study, two- and three-dimensional coordination polymers that melt were synthesized, [Ru(Cp)(C6 H5 R)][M{C(CN)3 }2 ] (R=H, Me, Et; M=K, Rb; Cp=C5 H5 ), which are complex salts comprising M[C(CN)3 ] and organometallic ionic liquids [Ru(Cp)(C6 H5 R)][C(CN)3 ]. They have anionic [M{C(CN)3 }2 ]n - coordination polymer frameworks, whose dimensionalities depend on the size of the organometallic cation inside. Their melting points decreased with increasing cation substituent length and size of the alkali metal ion (Tm =102-239 °C), and these low-melting-point coordination polymers exhibited incongruent melting, forming mixtures of solid M[C(CN)3 ] and ionic liquid upon melting. Using the same method, coordination polymers were synthesized with various bridging ligands, [Co(Cp)2 ][MX2 ] (X=B(CN)4 , C(CN)3 , N(CN)2 ; M=K, Na), as well as a paramagnetic coordination polymer, [Fe(Cp)2 ][K{C(CN)3 }2 ].

Coordination polymers of Cu(II), Co(II) and Cd(II) based on a tetramethyl-substituted terphenyldicarboxylic acid

Three new 3D-metal–organic frameworks based on 2′,3′,5′,6′-tetramethyl-[1,1′:4′,1′′-terphenyl]-4,4′′-dicarboxylic acid (H2L) and Co, Cu, and Cd nodes have been synthesized. The complexes were characterized by elemental, thermogravimetric analysis, IR spectroscopy, single crystal, powder X-ray diffraction and gas sorption experiments. The crystal structure of [Cu2L2(H2O)2]n (1) corresponds to a two-dimensional coordination polymer, in which the metal nodes are two crystallographically equivalent Cu(II) atoms linked by four μ2-O,O′ carboxylate ligands in a centrosymmetric {Cu2O10} paddle-wheel building block. The structure of compound [CoL(dmso)]n (2) has a 3D metal–organic coordination lattice, in which the metal centers are connected by the linear organic ligand to generate a dense three-dimensional coordination polymer. Also, a three-dimensional coordination network was identified in the case of compound [Cd2L2(dmf)]n (3), whose structure is very similar to that of compound 2. In compound 3, the carboxylate groups of the linear L2− spacers behave as μ2-κ3O, O′:O tridentate bridging ligands. The compounds have a high thermal stability. Polymers 3 and 1 have moderate porosity (specific surface areas of approximately 900 m2/g and 600 m2/g, respectively), while polymer 2 has a dense structure.

One-, two- and three-dimensional coordination polymers based on copper paddle-wheel SBUs as selective catalysts for benzyl alcohol oxidation

Copper-based coordination polymers, Cu2(μ2-MeCO2)4(DABCO) (1), [Cu(1,4-BDC-Br)(DABCO)0.5]. xDMF.yH2O (2) and Cu(1,4-BDC-OH)(DMF) (3) (1,4-BDC-Br = 2-bromoterephthalate, DABCO = triethylenediamine, 1,4-BDC-OH = 2-hydroxyterephthalate) were solvothermally synthesized. Two polymorphs of 1 (1a and 1b) were obtained which both contain 1-D chains with similar connectivity and different packing. Compound 2 is a 3-D metal-organic framework (MOF) and 3 exhibits a 2-D structure. Structural analyses of the coordination polymers showed that they all have similar paddle-wheel secondary building units (SBUs). The coordination polymers 1–3 were characterized by FT-IR, thermogravimetric analysis (TGA), powder X-ray diffraction (XRD) and atomic absorption spectroscopy. Compound 2 is further analyzed by nitrogen adsorption/desorption technique. The obtained coordination compounds were employed as heterogeneous catalysts for selective oxidation of benzyl alcohol to benzoic acid using CH2Cl2 as solvent and tert-butyl hydroperoxide (TBHP) as oxidant. The catalysts displayed good activity in the oxidation reaction and could be reused without noticeable loss of activity.

Temperature-Controlled Assembly/Reassembly of Two Dicarboxylate-Based Three-Dimensional Co(II) Coordination Polymers with an Antiferromagnetic Metallic Layer and a Ferromagnetic Metallic Chain.

Two new dicarboxylate-based three-dimensional cobalt coordination polymers, [Co(Me2mal)(bpe)0.5(H2O)]n (1) and [Co(Me2mal)(bpe)0.5]n (2), were synthesized from dimethylmalonic acid (H2-Me2mal) in temperature-controlled solvothermal reactions. Lower temperatures (60–80 °C) favored the formation of 1, while higher temperatures (120 °C) favored the production of 2. Compound 1 is comprised of Co(II) corrugated layers linked by syn–anti carboxylate bridges from the Me2mal2− ligands and pillared through bis-monodentate bpe groups. Compound 2 is comprised of a three-dimensional network involving one-dimensional Co–carboxylate chains bonded by antisymmetric µ4-Me2mal2− ligands and aligned parallel to the [001] direction. The solvothermal retreatment of crystalline samples of 1 in a DMF/H2O solvent at 120 °C allowed the structural reassembly, with complete conversion within 2 over 48 h. Magnetic analyses revealed that compound 1 exhibits both spin-orbital coupling and antiferromagnetic interactions through a syn–anti carboxylate (Me2mal2−) bridge exchange pathway [Co–Co separation of 5.478 Å] and compound 2 showed a ferromagnetic interaction resulting from the short Co–Co separation (3.150 Å) and the small Co–O–Co bridging angles (98.5° and 95.3°) exchange pathway which was provided by µ4-Me2mal2− bridging ligand.

Cadmium(II) three-dimensional coordination polymers constructed from 1,3,5-tris(4-carboxyphenoxy)benzene: synthesis, crystal structure, fluorescence and I2 sorption characterization.

Two three-dimensional (3D) CdII coordination polymers, namely poly[[di-μ-aqua-diaquabis{μ5-4,4',4''-[benzene-1,3,5-triyltris(oxy)]tribenzoato}tricadmium(II)] dihydrate], {[Cd3(C27H15O9)2(H2O)4]·2H2O}n, (I), and poly[[aqua{μ6-4,4',4''-[benzene-1,3,5-triyltris(oxy)]tribenzoato}(μ-formato)[μ-1,1'-(1,4-phenylene)bis(1H-imidazole)]dicadmium(II)] dihydrate], {[Cd2(C27H15O9)(C12H10N4)(HCOO)(H2O)]·2H2O}n, (II), have been hydrothermally synthesized from the reaction system containing Cd(NO3)2·4H2O and the flexible tripodal ligand 1,3,5-tris(4-carboxyphenoxy)benzene (H3tcpb) via tuning of the auxiliary ligand. Both complexes have been characterized by single-crystal X-ray diffraction analysis, elemental analysis, IR spectra, powder X-ray diffraction and thermogravimetric analysis. Complex (I) is a 3D framework constructed from trinuclear structural units and tcpb3- ligands in a μ5-coordination mode. The central CdII atom of the trinuclear unit is located on a crystallographic inversion centre and adopts an octahedral geometry. The metal atoms are bridged by four syn-syn carboxylate groups and two μ2-water molecules to form trinuclear [Cd3(COO)4(μ2-H2O)2] secondary building units (SBUs). These SBUs are incorporated into clusters by bridging carboxylate groups to produce pillars along the c axis. The one-dimensional inorganic pillars are connected by tcpb3- linkers in a μ5-coordination mode, thus forming a 3D network; its topology corresponds to the point symbol (42.62.82)(44.62)2(45.66.84)2. In contrast to (I), complex (II) is characterized by a 3D framework based on dinuclear cadmium SBUs, i.e. [Cd2(COO)3]. The two symmetry-independent CdII ions display different coordinated geometries, namely octahedral [CdN2O4] and monocapped octahedral [CdO7]. The dinuclear SBUs are incorporated into clusters by bridging formate groups to produce pillars along the c axis. These pillars are further bridged either by tcpb3- ligands into sheets or by 1,4-bis(imidazol-1-yl)benzene ligands into undulating layers, and finally these two-dimensional surfaces interweave, forming a 3D structure with the point symbol (4.62)(47.614). Compound (II) exhibits reversible I2 uptake of 56.8 mg g-1 with apparent changes in the visible colour and the UV-Vis and fluorescence spectra, and therefore may be regarded as a potential reagent for the capture and release of I2.

Solid–solid and solid–liquid conversion of sodium and silver nano coordination polymers

Solid-state conversion of a three-dimensional sodium coordination polymer [Na(μ6-HTar)]n (1), (H2Tar = (+)‐tartaric acid), synthesized by a sonochemical procedure, to a two-dimensional silver coordination polymer [Ag(μ3-HTar)(H2O)]n (2) has been observed upon mechanochemical cation exchange reaction of 1 with AgNO3. The conversion of 2 to 1 via solid-state reaction has also been investigated. These samples were characterized by IR spectroscopy, X‐ray powder diffraction (XRD), thermo gravimetric and differential thermal analyses (TG-DTA), Energy-dispersive X-ray spectroscopy (EDAX) and Scanning Electron Microscopy (SEM). It was observed that the conversion of compound 1 to compound 2 is irreversible. In addition it was confirmed that [Ag(μ3-HTar)(H2O)]n (2) converted to [Ag2(HTar)]n (3) during solid–liquid reaction in water.

Synthesis and crystal structure of a new coordination polymer based on lanthanum and 1,4-phenyl-enedi-acetate ligands.

Reaction in gel between the sodium salt of 1,4-phenyl-enedi-acetic acid (Na2C10O4H8-Na2 p-pda) and lanthanum chloride yields single crystals of the three-dimensional coordination polymer poly[[tetra-aqua-tris-(μ-1,4-phenyl-enedi-acetato)-dilanthanum(III)] octa-hydrate], {[La2(C10H8O4)3(H2O)4]·8H2O}∞. The LaIII coordination polyhedron can be described as a slightly distorted monocapped square anti-prism. One of the two p-pda2- ligands is bound to four LaIII ions and the other to two LaIII ions. Each LaIII atom is coordinated by five ligands, thereby generating a metal-organic framework with potential porosity properties.

Electrical Voltage Control of the Pressure-Induced Spin Transition at Room Temperature in the Microporous 3D Polymer [Fe(pz)Pt(CN)4

Fine control and direct monitoring of the spin crossover properties driven by pressure at room temperature are reported for the porous three-dimensional coordination polymer {Fe(pz)[Pt(CN)4]} by using a homemade pressure cell that transforms a DC voltage into pressure. The pressure induced spin state switching is steadily driven through a piezoelectric ceramic element, which transforms the voltage 1−4 kV in pressures in the 0.001−0.035 GPa range. At the same time, the spin state is easily monitored through changes in the optical spectra of the title compound. The results demonstrate that {Fe(pz)[Pt(CN)4]} responds to as small pressure variations as 0.001 GPa (10 atm), thereby proving its efficacy to work as an effective pressure sensor.

Two chiral cadmium carboxylate framework isomers generated by spontaneous resolution: synthesis, structures and properties

Two three-dimensional (3-D) chiral coordination polymers, [Cd(NDC)(DMF)]n (1L and 1D: H2NDC = 1,4-naphthalenedicarboxylic acid and DMF = N,N′-dimethylformamide), have been synthesized by introducing the rigid achiral dicarboxylic acid ligand under solvo-thermal conditions, without chiral template or additives. Both chiral Cd-CPs were characterized by single crystal X-ray crystallography, and structural analysis indicates that 1L and 1D are enantiomers based on the zigzag [Cd(COO)2(DMF)]n rod secondary building units, featuring the left- or right-hand 21 Cd-O-C-O-Cd helix chains and left- or right-hand 41 screw [Cd(NDC)]n columns, respectively. The FT-IR, TGA, powder X-ray diffraction and solid-state luminescence of 1 have been investigated. It is intriguing that the evidence from the circular dichroism spectroscopies confirms enantiomeric excess in the whole spontaneous resolution crystallization.

A Zn(ii) metal-organic framework based on bimetallic paddle wheels as a luminescence indicator for carcinogenic organic pollutants: phthalate esters.

Based on the multifunctional ligand 3-(1H-1,2,4-triazol-1-yl)isophthalic acid (H2TIA), a three-dimensional coordination polymer, namely {[Zn(TIA)]·DMA}n (Zn-1) was synthesized solvothermally. Single-crystal X-ray diffraction analyses confirmed that Zn-1 is a 3D framework composed of binuclear Zn2 paddle wheels with one-dimensional channels long the a direction. Further topological analyses revealed that MOF Zn-1 existed as a (3,6)-connected rtl binodal net {4·62}2{42·610·83}. Furthermore, the luminescence explorations indicate that complex Zn-1 is the first MOF for luminescent probing of phthalate esters (carcinogenic organic pollutants) with a high quenching-efficiency constant and low fluorescence-detection limit.

An unprecedented hetero-bimetallic three-dimensional spin crossover coordination polymer based on the tetrahedral [Hg(SeCN)4]2- building block.

Self-assembly of octahedral FeII ions, trans-1,2-bis(4-pyridyl)ethane (bpe) bridging ligands and [Hg(XCN)4]2- (X = S (1), Se (2)) tetrahedral building blocks has afforded a new type of hetero-bimetallic HgII-FeII spin-crossover (SCO) 3D 6,4-connected coordination polymer (CP) formulated {Fe(bpe)[Hg(XCN)4]}n. For X = S (1), the ligand field is close to the crossing point but 1 remains paramagnetic over all temperatures. In contrast, for X = Se (2) the complex undergoes complete thermal induced SCO behaviour centred at T1/2 = 107.8 K and complete photoconversion of the low spin state into a metastable high-spin state (LIESST effect) with TLIESST = 66.7 K. The current results provide a new route for the design and synthesis of new SCO functional materials with non-Hoffmann-type structures.

The trinuclear platinum(ii) complex in Vèzes' red salt as a building block of coordination polymers.

One-dimensional (1D) and three-dimensional (3D) coordination polymers comprising triangular [Pt3(NO2)6(μ3-O)]2- ([Pt3]2-) units were prepared from K2[Pt3]·3H2O (1), also known as Vèzes' red salt. The reaction between 1 and excess 18-crown-6 ether afforded the 1D coordination polymer [K(18-crown-6)]2[Pt3] (2), whereas the reaction between 1, excess 18-crown-6 ether, and AgPF6 afforded the 1D coordination polymer [Ag(18-crown-6)]2[Pt3]·(CH3)2CO (3). However, the reaction between 1 and equimolar amounts of 18-crown-6 and AgPF6 afforded the 3D coordination polymer [Ag2(18-crown-6)][Pt3]·(CH3)2CO (4). Furthermore, the 3D coordination polymer [Ag2Pt3(μ3-O)(NO2)6((CH3)2CO)2]·(CH3)2CO (5) containing three Pt2+ → Ag+ dative bonds was obtained by the reaction of 1, Bu4NPF6, and AgPF6. The N2, O2, and CO2 gas absorption isotherms of 1-5 were obtained, revealing that the dry crystals of 4 exhibit a selective CO2 absorption ability.

SYNTHESIS AND STRUCTURE OF POTASSIUM TETRAETHYLAMMONIUM HEXATHIOCYANATOPLATINATE(IV)

Potassium tetraethylammonium hexathiocyanatoplatinate(IV) (Et4N)(K)[Pt(SCN)6] (I) was synthesized by the reaction of potassium hexathiocyanatoplatinate(IV) with tetraethylammonium chloride in acetonitrile aqueous solution. Slow evaporation of the solvent led to the formation of large red-brown crystals. The product structure was determined by XRDA. The X-ray diffraction pattern of crystal I was carried out on a Bruker D8 QUEST diffractometer (MoKα radiation, λ = 0.71073 Å, graphite monochromator). [С14H20N7KPtS6, M = 712.92, Crystal system monoclinic, space group C 2/c, a = 10.432(8), b = 14.767(13), c = 16.300(13) Å, V = 2510(4) Å3, Z = 4, µ = 6.272 mm-1, F(000) = 1384, crystal size 0.86×0.66×0.50 mm]. The tetrahedral configuration of the tetraethylammonium cation is slightly distorted (CNC angles are 105.5(5)º-111.8(4)º, bond lengths N-С are 1.503(5)-1.519(5) Å). Platinum ions in anions have octahedral coordination (trans-angles SPtS are 180º, cis-angles SPtS are (88.47(4)º-91.53(4)º). The bond lengths Pt-S are equal to 2.373 (2)-2.37(2) Å. Potassium cations are coordinated by six nitrogen atoms of thiocyanate groups (distances N K (2.828(4)-2.896 (4) Å). Trans-angles NKN (128.44 (15)º-146.9 (2)º) are far from ideal values for the octahedron. Bridged thiocyanate ligands are bonded cations of the platinum and potassium. Ambidentate thiocyanate ligands are simultaneously coordinated to the K+ cation by nitrogen atoms. By means of the bridged thiocyanate ligands a three-dimensional coordination polymer is formed. The resulting structure is a three-dimensional grid, in the cells of which the cations of tetraethylammonium (Et4N)+ are located.

Luminescent and Magnetic Properties of Coordination Polymers Induced by Coordinating Modes of a Bis(oxamate) Ligand.

The reactions of an unexploited N,N'-5-carboxyl-1,3-phenylenebis(ethyl oxamate) (HEt2 L) ligand with different Mn2+ and Cd2+ salts under solvothermal conditions afforded four three-dimensional (3D) coordination polymers (CPs): [Mn1.5 L(H2 O)2 ]⋅H2 O (1) [Mn2 L(C2 O4 )0.5 (NMP)(H2 O)] ⋅ NMP (2), [Cd1.5 L(H2 O)2.5 ] ⋅ H2 O (3) and [Cd2 L(C2 O4 )0.5 (H2 O)3 ] ⋅ H2 O (4) (NMP=N-methyl pyrrolidone). L, generated by the in-situ hydrolysis of HEt2 L, displays four kinds of coordinating modes through oxamate and carboxylate groups as well as different syn-syn and syn-trans configurations. The resulting novel (3,4,5)-, (3,4,6)-, (4,5)- and (4,4,4,5)-connected topologies for 1-4 were formed. Among them, 1 has interesting 1D metal-oxamate zigzag chains, 2 contains 1D channels with a free void of 52.5 %, 3 consists of an unprecedented Cd-oxamate layer, 4 has a novel Cd-oxamate-oxalate chain. The antiferromagnetic interactions of 1 and 2 were observed, meanwhile 3 and 4 exhibit solid-state luminescence with the maximum emission bands at 483 and 479 nm, respectively, under an excitation of 332 nm.

Two- and three-dimensional coordination polymers based on zinc(II) and furan-2,5-dicarboxylic acid: structure variation due to metal-to-linker ratio.

Two ZnII-based coordination polymers (CPs) were synthesized by the hydrothermal method, using Zn(NO3)2·6H2O and furan-2,5-dicarboxylic acid (FDCA) in dimethylformamide (DMF) solvent, at 95 °C. Poly[tetrakis(dimethylazanium) [tetrakis(μ2-furan-2,5-dicarboxylato-κ2O2:O5)dizinc(II)]], {(C2H8N)4[Zn2(C6H2O5)4]}n or {[DMA]4[ZnII2(FDC)4]}n (DMA = dimethylazanium and FDC= furan-2,5-dicarboxylate), (1), was obtained with a 1:1 molar ratio of ZnII and FDCA. It crystallized in the monoclinic space group C2/c. Coordinated by ZnII ions, FDC2- ligands form 21 double-stranded helices propagating along the b axis. The helices are interconnected and extend laterally in the a direction, forming a two-dimensional (2D) sheet-like network. The 2D sheets are stacked along the c direction without interconnections. DMA cations are cocrystallized in (1) and are hydrogen bonded with carboxylate O atoms of the FDC2- ligands. The hydrogen-bonding pattern consists of R22(4) and R22(10) motifs alternating in a chain. Poly[bis(dimethylazanium) [bis(μ4-furan-2,5-dicarboxylato-κO2:κO2':κO5:κO5)bis(μ3-furan-2,5-dicarboxylato-κO2:κO2':κO5)dizinc(II)] dimethylformamide 3.08-solvate], {(C2H8N)2[Zn2(C6H2O5)4]·3.08C3H7NO}n or {[DMA]2[ZnII3(FDC)4]·3.08DMF}n, (2), was obtained with a 1:2 molar ratio of ZnII and FDCA. It crystallized in the monoclinic space group P21/c, forming a three-dimensional network. The pores are filled with DMA cations and DMF solvent molecules.

Emissive Azobenzenes Delivered on a Silver Coordination Polymer.

Azobenzene has become a ubiquitous component of functional molecules and polymeric materials because of the light-induced trans → cis isomerization of the diazene group. In contrast, there are very few applications utilizing azobenzene luminescence, since the excitation energy typically dissipates via nonradiative pathways. Inspired by our earlier studies with 2,2'-bis[ N,N'-(2-pyridyl)methyl]diaminoazobenzene (AzoAM oP) and related compounds, we investigated a series of five aminoazobenzene derivatives and their corresponding silver complexes. Four of the aminoazobenzene ligands, which exhibit no emission under ambient conditions, form silver coordination polymers that are luminescent at room temperature. AzoAE pP (2,2'-bis[ N,N'-(4-pyridyl)ethyl]diaminoazobenzene) assembles into a three-dimensional coordination polymer (AgAAE pP) that undergoes a reversible loss of emission upon the addition of metal-coordinating analytes such as pyridine. The switching behavior is consistent with the disassembly and reassembly of the coordination polymer driven by displacement of the aminoazobenzene ligands by coordinating analytes.

Synthesis, characterization and electrochemical properties of two metal cobalt complexes constructed by tetradentate carboxylic

Two new three-dimensional coordination polymers (CPs), [Co(H2L2−) (bibp)]·2H2O (1) and [Co2(L4−) (bib)2]·8H2O (2) (bib = 1,4-diimidazolyl butane, bibp = 4,4′-diimidazolylbiphenyl) have been solvo-/hydrothermal prepared based on tetradentate ligand 5,5-(pentane-1,4-diylbis (oxy))diisophthalic acid (H4L). In CP 1, two chains was formed by Co(II) ion with ligands H2L2− and bibp, respectively, then two chains form into a 2D layer through Co(II) ion. The same two 2D layers constitute a AB layer by inverted manner, then a 3D framework was obtained through the combination of AB layer by π-π stacking. In CP 2, Co (II) atoms are connected by neighboring carboxylic acid ligands L4− to generate 2D layer, then being further connected with nitrogen-containing ligand bib, the 2D layer form a 3D supramolecular network through Co(II) ions. In addition, the electrochemical behaviors of complexes 1 and 2 have been reported.