Synthesis,Crystal Structures,Thermal and Magnetic Properties of New Selenocyanato Coordination Polymers with Pyrazine as Co‐Ligand

Reaction of iron(II), cobalt(II) and nickel(II) selenocyanate with pyrazine in water at room temperature leads to the formation of the isotypic new ligand‐rich 1:2 (1:2 = ratio between metal and co‐ligand) compounds [M(NCSe)₂(pyrazine)₂]_n (M = Fe ( 1 ), Co ( 2 ), Ni ( 3 )). The crystal structure of 2 was determined by X‐ray single crystal analysis and those of 1 and 3 were refined from X‐ray powder data with the Rietveld method. In their crystal structure the metal(II) cations are coordinated by four pyrazine co‐ligands, which connect them into layers, and two terminally N‐bonded selenocyanato anions in a distorted octahedral arrangement. The terminal coordination mode of the selenocyanato anions was further emphasized by IR spectroscopic investigations. On heating, all compounds decompose in a single heating step without the formation of ligand‐deficient intermediates like previously reported for related thiocyanato compounds. Magnetic measurements of compound 1 show a long‐range antiferromagnetic ordering with an ordering temperature of T_N = 6.7 K, which must be mediated by the aromatic π‐system of the pyrazine ligand, whereas 2 and 3 show only Curie–Weiss behavior with antiferromagnetic exchange interactions.     

Synthesis,Crystal Structure,and Magnetic Properties of a New Coordination Polymer Framework [CoII(4,4′‐bpy)(N3)2]n

A new cobalt(II) coordination polymer containing 4,4′‐bipyridine and azide as bridging ligand, [Co^II(4,4′‐bpy)(N₃)₂]_n ( 1 ) was synthesized under mild hydrothermal conditions and was characterized by single‐crystal X‐ray diffraction studies and magnetic susceptibility measurements. It exhibits an acentric structure, in which cobalt(II) ions are linked through end‐to‐end (EE) azido groups. The 4,4′‐bpy ligands are coordinated on the axial positions of the octahedral environment reinforcing the intermetallic connections and resulting in a network. Circular dichroism spectra of the compound exhibit a maximum negative Cotton effect at 260 nm, which indicates the chiral nature of 1 . Variable temperature magnetic susceptibility measurements in the temperature range 2–300 K reveal the existence of antiferromagnetic couplings in the framework.     

Two New Lead(II) Coordination Polymers with (Substituted) Bipyridine and Auxiliary Nitrate Ligands

The reaction of lead(II) nitrate with 4,4′‐bipyridine (4,4′‐bpy) and 4,4′‐dimethyl‐2,2′‐bipyridine (4,4′‐dm‐2,2′‐bpy) or 5,5′‐dimethyl‐2,2′‐bipyridine (5,5′‐dm‐2,2′‐bpy) resulted in the fomation of single crystals of [Pb₂(4,4′‐bpy)(5,5′‐dm‐2,2′‐bpy)₂(NO₃)₄] ( 1 ) and [Pb₃(4,4′‐bpy)₂(4,4′‐dm‐2,2′‐bpy)₂(NO₃)₆] ( 2 ). The new compounds have been characterized by single‐crystal X‐ray diffraction structure analysis as well as through elemental analysis, IR, ¹H‐NMR and ¹³C‐NMR spectroscopy and their stability has been studied by thermal analysis. In the crystal structure of ( 1 ) formula‐like dimers are further connected to a 2‐D network through the auxiliary nitrate ligands. The crystal structure of ( 2 ) exhibits two crystallographically independent Pb^II central atoms (in a ratio of 1:2). With the aid of the 4,4′‐bpy and the nitrate ions, a 3‐D polymeric structure is achieved.     

Synthesis,Structures, and Magnetic Properties of New Thiocyanato Coordination Polymers with 4‐(3‐Phenylpropyl)pyridine as Ligand

The reaction of different metal salts with 4‐(3‐phenylpropyl)pyridine (ppp) lead to the formation of compounds of composition M(NCS)₂(ppp)₄ [M = Mn ( Mn‐1 ); Fe ( Fe‐1 ), Ni ( Ni‐1 ); Cd ( Cd‐1 )], M(NCS)₂(ppp)₂(H₂O)₂ [M = Mn ( Mn‐2 ); Ni ( Ni‐2 )] and [M(NCS)₂(ppp)₂]_n [M = Mn ( Mn‐3 ); Ni ( Ni‐3 ); Cd ( Cd‐3 )]. On heating compounds M‐1 decompose without the formation of any ppp deficient intermediate. In contrast, on heating, Ni‐2 transforms into a compound of composition M(NCS)₂(ppp)₂ that does not correspond to Ni‐3 . Unfortunately, this compound is of low crystallinity and therefore, its structure cannot be determined. The crystal structures of compounds M‐1 and M‐2 consist of discrete complexes, in which the metal cations are octahedrally coordinated. In compounds M‐3 the metal cations are linked by pairs of μ‐1,3‐bridging anions into chains. IR spectroscopic investigations show, that the value of the asymmetric CN stretching vibration depend on the coordination mode of the anionic ligand as well as on the nature of the metal cation. Magnetic measurements reveal that Ni‐3 shows only Curie‐Weiss behavior without any magnetic anomaly. A similar behavior is also found for Ni‐3 . Comparison of the magnetic properties of Ni‐3 with those of similar compounds indicates that the magnetic properties are only minor influenced by the Co‐ligand.     

(4,4′‐Bipyridine)mercury(II) Coordination Polymers,Syntheses, and Structures

Mercury(II) complexes with 4,4′‐bipyridine (4,4′‐bipy) ligand were synthesized and characterized by elemental analysis, and IR, ¹H‐ and ¹³C‐NMR spectroscopy. The structures of the complexes [Hg₃(4,4′‐bipy)₂(CH₃COO)₂(SCN)₄]_n ( 1 ), [Hg₅(4,4′‐bipy)₅(SCN)₁₀]_n ( 2 ), [Hg₂(4,4′‐bipy)₂(CH₃COO)₂]_n(ClO₄)_2n ( 3 ), and [Hg(4,4′‐bipy)I₂]_n ( 4 ) were determined by X‐ray crystallography. The single‐crystal X‐ray data show that 2 and 4 are one‐dimensional zigzag polymers with four‐coordinate Hg‐atoms, whereas 1 is a one‐dimensional helical chain with two four‐coordinate and one six‐coordinate Hg‐atom. Complex 3 is a two‐dimensional polymer with a five‐coordinate Hg‐atom. These results show the capacity of the Hg‐ion to act as a soft acid that is capable to form compounds with coordination numbers four, five, and six and consequently to produce different forms of coordination polymers, containing one‐ and two‐dimensional networks.     

Investigations on the Structure Diversity and Thermal Degradation Behavior of CdII and ZnII Thiocyanato Coordination Compounds based on 3‐Acetylpyridine as Neutral Co‐Ligand

Reaction of Cd^II and Zn^II thiocyanate with 3‐acetylpyridine leads to the formation of the new Cd^II and Zn^II coordination compounds [Cd(NCS)₂(3‐acetylpyridine)₄] ( 1A ), [Cd(NCS)₂(3‐acetylpyridine)₂]_n ( 1B ), [Cd(NCS)₂(3‐acetylpyridine)]_n ( 1C ) and [Zn(NCS)₂(3‐acetylpyridine)₂] ( 2A ). Compound 1A consists of discrete complexes, in which the metal centers are octahedrally coordinated by four terminal bonded N‐donor co‐ligands and two terminal N‐bonded thiocyanato anions. In compound 2A the metal centers are only tetrahedrally coordinated by two terminal bonded N‐donor co‐ligands and two terminal N‐bonded thiocyanato anions. In compound 1B the Cd^II cations are octahedrally coordinated by two terminal bonded N‐donor co‐ligands and four thiocyanato anions. The metal centers are linked by μ‐1, 3 bridging thiocyanato anions into chains. In compound 1C the metal cations are octahedrally coordinated by two μ‐1, 5 bridging 3‐acetyl‐pyridine ligands and four μ‐1, 3 bridging thiocyanato anions building up a three‐dimensional coordination network. Investigations on the thermal degradation behavior of all compounds using simultaneous differential thermoanalysis and thermogravimetry as well as X‐ray powder diffraction and IR spectroscopy prove that on heating compound 2A decompose without the formation of 3‐acetylpyridine‐deficient intermediates. In contrast, for compound 1A a stepwise decomposition is observed, leading to the formation of the 3‐acetylpyridine‐deficient compound [Cd(NCS)₂(3‐acetylpyridine)₂]_n ( 1B ) which decomposes on further heating     

Synthesis,Crystal Structures,and Thermal Properties of New Zinc(II) Thiocyanato Coordination Compounds

Reaction of zinc(II) thiocyanate with pyrazine, pyrimidine, pyridazine, and pyridine leads to the formation of new zinc(II) thiocyanato coordination compounds. In bis(isothiocyanato‐N)‐bis(μ₂‐pyrazine‐N,N) zinc(II) ( 1 ) and bis(isothiocyanato‐N)‐bis(μ₂‐pyrimidine‐N,N) zinc(II) ( 2 ) the zinc atoms are coordinated by four nitrogen atoms of the diazine ligands and two nitrogen atoms of the isothiocyanato anions within slightly distorted octahedra. The zinc atoms are connected by the diazine ligands into layers, which are further linked by weak intermolecular S ··· S interactions in 1 and by weak intermolecular C–H ··· S hydrogen bonding in 2 . In bis(isothiocyanato‐N)‐bis(pyridazine‐N) ( 3 ) discrete complexes are found, in which the zinc atoms are coordinated by two nitrogen atoms of the isothiocyanato ligands and two nitrogen atoms of the pyridazine ligands. The crystal structure of bis(isothiocyanato‐N)‐tetrakis(pyridine‐N) ( 4 ) is known and consists of discrete complexes, in which the zinc atoms are octahedrally coordinated by two thiocyanato anions and four pyridine molecules. Investigations using simultaneous differential thermoanalysis and thermogravimetry, X‐ray powder diffraction and IR spectroscopy prove that on heating, the ligand‐rich compounds 1 , 2 , and 3 decompose without the formation of ligand‐deficient intermediate phases. In contrast, compound 4 looses the pyridine ligands in two different steps, leading to the formation of the literature known ligand‐deficient compound bis(isothiocyanato‐N)‐bis(pyridine‐N) ( 5 ) as an intermediate. The crystal structure of compound 5 consists of tetrahedrally coordinated zinc atoms which are surrounded by two isothiocyanato anions and two pyridine ligands. The structures and the thermal reactivity are discussed and compared with this of related transition metal isothiocyanates with pyrazine, pyrimidine, pyridazine, and pyridine.     

Syntheses,Crystal Structures,and Properties of Metal(II) Coordination Polymers based on Flexible Ligand 1,3‐Bis(4‐phenoxy)benzenedicarboxylic Acid and Bis(benzimidazole)

Three new coordination polymers, [Zn(PBDC)(bbbm)_0.5]_n ( 1 ), [Co(PBDC)(bbbm)]_n ( 2 ), and [Cd(PBDC)(bbbm)]_n ( 3 ) were prepared via hydrothermal reactions of different metal(II) nitrates with flexible 1,3‐bis(4‐phenoxy)benzenedicarboxylic acid (H₂L) and 1,1‐(1,4‐butanediyl)bis(benzimidazole) ligand. All these complexes were fully characterized by elemental analysis, FT‐IR, thermogravimetric analysis (TGA), powder X‐ray diffraction, and single‐crystal X‐ray diffraction. Structure analyses revealed that complex 1 has a 2D→2D twofold interpenetrating framework simplified by a 4‐connected sql net with point symbol (4⁴.6²), whereas complexes 2 and 3 are isostructural and exhibit a 2D→2D twofold interpenetrating framework rationalized as a three‐connected hcb net with point symbol (6³). Complexes 1 – 3 further expand to 3D supramolecular structures through non‐covalent C–H ··· O interactions. Additionally, the luminescent and magnetic properties of some of these complexes were studied. Complex 3 presents ideal photoluminescent behavior, whereas complex 2 shows antiferromagnetic coupling between the central Co^II ions, suggesting its latent application in magnetic material.     

Synthesis,Structure, and Magnetic Properties of a Copper(II) Metal‐Organic Framework with Biphenyl‐2,2′,4,4′‐tetracarboxylic Acid

The 2D Cu^II metal‐organic framework [Cu₂(bptc)(H₂O)₄]_n · 4nH₂O ( 1 ) (H₄bptc = biphenyl‐2,2′,4,4′‐tetracarboxylic acid) was hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction and magnetic measurements. In the structure, bptc^4– serves as a twisted Π‐shaped organic building block to connect paddlewheel [Cu₂(COO)₄] dinuclear units and mononuclear units through 2‐/2′‐carboxylate and 4‐/4′‐carboxylate, respectively. According to the magnetic analysis using a dimer‐plus‐monomer model, strong antiferromagnetic coupling is operative within the dinuclear unit (J = –311 cm^–1 based on H = –J S ₁ S ₂), and the compound behaves like a mononuclear molecule at low temperature.     

The Coordination Chemistry of Iron with the 1,4‐Bis(2‐pyridyl‐methyl)piperazine Ligand

The behaviour of Fe^II and Fe^III ions in combination with the potential ligand 1,4‐bis(2‐pyridyl‐methyl)piperazine (BPMP) under anhydrous conditions has been investigated. BPMP has been reacted with FeCl₂, FeCl₃ and [Fe(OTf)₂(MeCN)₂]. This led to the isolation of four new complexes, which were fully characterized and structurally investigated by single crystal X‐ray diffraction. It turned out that in the presence of chloride co‐ligands Fe^III favours the tetradentate coordination mode of BPMP with the piperazine unit in a boat configuration, like for instance in [BPMP(Cl)Fe(μ‐O)FeCl₃] or [BPMP‐FeCl₂][FeCl₄], ( 1 ). However, the employment of FeCl₂ leads to the formation of a coordination polymer [BPMP‐FeCl₂]_n, ( 2 ), containing the piperazine ring in a chair configuration binding to two iron centres each. 2 can only be dissolved in very polar solvents like dmf which is capable of breaking up the polymeric structure under formation of [Cl₂(dmf)Fe(μ‐BPMP‐1κ²N,N:2κ²N,N))Fe(dmf)Cl₂]·2 dmf, ( 3 ). In contrast, using [Fe(OTf)₂(MeCN)₂] instead of FeCl₂ as the starting material leads to a mononuclear Fe^II complex with BPMP bound in the desirable tetradentate fashion: [BPMP‐Fe(OTf)₂], ( 4 ). Unlike other complexes with tetradentate N/py ligands the two residual ligands in 4 are bound almost trans to each other with the potential to adopt a cis orientation under oxidising conditions, and it will be interesting to exploit its catalytic properties in future.     

Synthesis,Structures, and Properties of Cadmium(II) and Nickel(II) Coordination Polymers Based on a 4,4′‐Biphenyl‐Containing Ligand and Aliphatic Carboxylic Acids

The coordination polymers [Cd₂(bbmb)₂(L₁)(HL₁)_0.5(H₂O)]_n ( 1 ), [Cd₂(bbmb)₂(L₂)₂(H₂O) · (H₂O)]_n ( 2 ), and [Ni(bbmb)₂(L₃)]_n ( 3 ), were synthesized by the hydrothermal reaction of 4,4′‐bis(benzimidazol‐1‐ylmethyl)biphenyl (bbmb) with Cd^II/Ni^II ions in the presence of three flexible aliphatic acids [tricarballylic acid (H₃L₁), succinate (H₂L₂), and adipate (H₂L₃)]. Complexes 1 – 3 were structurally characterized by elemental analysis, IR spectroscopy and single‐crystal and X‐ray powder diffraction analyses. Complex 1 presents a 3D 3‐nodal (3,4,4)‐connected net with 3 , 4 , 4T78 topology, 2 exhibits a 3D network with 6⁶‐ dia topology, whereas 3 is a chain structure and further extended by hydrogen bonding interactions to form a 2D supramolecular network. Structural diversity of these complexes indicates that these frameworks could be tuned by the conformation of bbmb ligand and the different coordination modes of the aliphatic carboxylate co‐ligands. The thermal and fluorescence properties, the catalytic activities of complexes 1 – 3 in a Fenton‐like process were investigated.     

Three Novel 1‐H‐Benzimidazole‐5‐Carboxylate‐Based Nickel(II)/Cobalt(II) Coordination Polymers: Synthesis,Crystal Structures,Luminescent, and Magnetic Properties

Three 1H‐benzimidazole‐5‐carboxylate (Hbic^–)‐based coordination polymers, {[Ni(H₂O)(Hbic)₂] · 2H₂O}_n ( 1 ), {[Ni(H₂O)₂(Hbic)₂] · 3H₂O}_n ( 2 ), and {[Co₂(H₂O)₄(Hbic)₄] · 4DMF · 3H₂O}_n ( 3 ) were obtained by reactions of the ligand H₂bic and Ni^II or Co^II salts in the presence of different structure directing molecules. They were structurally characterized by single‐crystal X‐ray diffraction, IR spectra, elemental analysis, thermal stability, luminescent, and magnetic measurements. Structural analysis suggests that the three polymers exhibit a 2D (4, 4) layer for 1 and 1D linear double chains for both 2 and 3 due to the variable binding modes and the specific spatial orientation of the Hbic^– ligand towards the different paramagnetic metal ions, which were further aggregated into different 3D supramolecular architectures by popular hydrogen‐bonding interactions. Weak and comparable antiferromagnetic couplings mediating by Hbic^– bridge are observed between the neighboring spin carriers for 2 and 3 , respectively. Additionally, complexes 1 – 3 also display different luminescence emissions at room temperature due to the ligand‐to‐metal charge transfer.     

Crystal Structure and Magnetic Properties of Copper(II) and Nickel(II) Binuclear Complexes with Bisacylhydrazones Based on 2,6‐Diformyl‐4‐methylphenol

The series of binuclear Cu(II) and Ni(II) complexes with an asymmetrical exchange fragment based on 2,6‐diformyl‐4‐methylphenol bishydrazone has been synthesized for the first time. The compositions and structures of both ligands and its complexes have been established with the data of IR, ¹H NMR, and extended X‐ray absorption fine structure (EXAFS) spectroscopical studies as well as magnetic measurements. The structure of [Ni₂L₃(μ‐Pz)] · 2CH₃OH (L = triply deprotonated form of bishydrazone, Pz = pyrazol) was confirmed by X‐ray crystallographic analysis. In this complex, the coordination environment of two nickel ions is quite different, one nickel atom is square‐planar and the other is distorted octahedral coordinated. The values of exchange parameter calculated in terms of HDVV theory have been compared with the features of an asymmetrical exchange fragment's electronic and geometrical structure.     

Influence of CF3 Substituents on the Spin Crossover Behavior of Iron(II) Coordination Polymers with Schiff Base-like Ligands

A Schiff base-like ligand bearing CF₃ substituents was synthesized and converted to iron(II) coordination polymers [{FeL(L_ax)}_n] using five different bridging ligands L_ax. The structure of the coordination polymers was investigated using powder X-ray diffraction and single-crystal X-ray diffraction in the case of [{FeL(bipy)}_n]. The later revealed an untypical ABAB pattern of alternating equatorial ligands rotated by 180° with regard to each other along the chain. The temperature-dependent magnetic behavior was investigated with a SQUID magnetometer and the spin states at room temperature were confirmed by ⁵⁷Fe-Mössbauer spectroscopy. Three out of five coordination polymers show spin crossover behavior in the temperature range between 50 and 400 K with different kind of curve progressions (abrupt, gradual, step-wise). The other two coordination polymers are either fully highspin or fully low spin.     

Hydrogen‐Bond‐Based Magnetic Exchange Between μ‐Diethylnicotinamide(aqua)bis(X‐salicylato)copper(II) Polymeric Chains

Polymeric salicylatocopper(II) complexes of unusual composition [C u(X‐ sal)₂( μ‐denia)(H₂O)]_n [denia = diethylnicotinamide, and X‐sal = 5‐methylsalicylate ( 1 ), 3‐methylsalicylate ( 2 ), 4‐methoxysalicylate ( 3 ), 3,5‐dichlorosalicylate ( 4 ) and 3,5‐dibromosalicylate ( 5 )] were synthesized and characterized. Magnetic measurements were performed in the temperature range 1.8–300 K. The structural unit of all complexes consists of a Cu^II atom, which is monodentately coordinated by the pair of X‐salicylate anions in trans positions. Water and the diethylnicotinamide ligand occupy the other two basal plane positions of the tetragonal pyramid. The axial positions are occupied by a diethylnicotinamide oxygen atom of neighboring structural units, thus forming a spiral polymeric structure parallel to b axis. Magnetic measurements showed that all complexes 1 – 5 exhibit a susceptibility maximum at about 6–8 K. The obtained data fit to Bleaney–Bowers equation gave singlet‐triplet energy gaps 2J = –8.60 cm^–1 for 1 , 2J = –6.57 cm^–1 for 2 , 2J = –8.57 cm^–1 for 3 , 2J = –6.82 cm^–1 for 4 , and 2J = –6.45 cm^–1 for 5 . The supramolecular structure based on hydrogen bonds [described by supramolecular synthons R₂²(10) and R₂²(12)] is the pathway for antiferromagnetic interactions of the magnetically coupled pairs of copper atoms of neighboring chains within the 2D supramolecular layers. The results of the magnetic measurements suggest involvement of the COO groups in the magnetic interaction pathway for all five complexes.     

Fluorescent Sensing Properties of Three Coordination Polymers Constructed by 3,5‐Di(2′,5‐dicarboxylphenyl)pyridine Ligand

Three Cd^II coordination polymers (CPs), named as {[Cd₂(DDPP)(DMF)(H₂O)] · DMF}_n ( 1 ), {[Cd₂(DDPP)(H₂O)₂] · DMA · H₂O}_n ( 2 ), [Cd(H₂DDPP)]_n ( 3 ), based on 3,5‐di(2′,5‐dicarboxylphenyl)pyridine) (H₄DDPP), were synthesized under solvothermal methods. Structural analysis indicates that the H₄DDPP ligand of 1 – 3 adopt (κ₁‐κ₁)‐(κ₁‐κ₁)‐(κ₁‐κ₂)‐(κ₁‐κ₁)‐μ₈, (κ₁‐κ₁)‐(κ₁‐κ₂)‐(κ₁‐κ₂)‐(κ₁‐κ₁)‐μ₁₀, and (κ₀‐κ₀)‐(κ₁‐κ₂)‐(κ₁‐κ₂)‐(κ₀‐κ₀)‐μ₆ coordination modes, respectively. CP 1 is a 2‐nodal (4,8)‐c alb ‐ 4 , 8 ‐ Pbcn network. CP 2 is a 3D 4,8‐c flu/fluorite network. CP 3 displays a 2D layer, which is further connected with hycrogen‐bonding interactions between layers to form supramolecular framework. Moreover, the fluorescent features of 1 – 3 were studied in aqueous systems and the values of detection limit (DL) are also calculated by 3σ/k_sv. The results reveal that 1 – 3 have good ability on probing Cr^VI/Fe^III ions.     

Two‐Dimensional Monovalent Copper Halide Coordination Polymers Incorporating Anti‐Conformation 3,3′‐Bipyridine

Hydrothermal treatment of aqueous mixtures of copper(II) halides and 3,3′‐bipyridine (3,3′‐bpy) has afforded the coordination polymers [CuCl(3,3′‐bpy)]_n ( 1 ) and [Cu₂Br₂(3,3′‐bpy)]_n ( 2 ), which were analyzed via single crystal X‐ray diffraction, infrared spectroscopy, and elemental analysis. The structure of 1 consists of two‐dimensional (2‐D) layers constructed from the linkage of castellated one‐dimensional (1‐D) [CuCl]_n stepped chains through anti‐conformation 3,3′‐bpy tethers. Compound 2 presents a related 2‐D sheet motif, albeit built from infinite 1‐D [Cu₂Br₂]_n ladders strutted by 3,3′‐bpy ligands in anti conformation. In both cases neighboring 2‐D sheets stack into 3‐D via weak C–H···halogen interactions.     

Effect of Metal Ions on the Structures of Coordination Polymers Based on Biphenyl‐2,2′,4,4′‐Tetracarboxylate

Two new coordination polymers, {[Cd₂(btc)(2,2′‐bpy)₂] · H₂O}_n ( 1 ) and [Zn₂(btc)(2,2′‐bpy)(H₂O)]_n ( 2 ) (H₄btc = biphenyl‐2,2′,4,4′‐tetracarboxylic acid, 2,2′‐bpy = 2,2′‐bipyridine), were synthesized hydrothermally under similar conditions and characterized by elemental analysis, IR spectra, TGA, and single‐crystal X‐ray diffraction analysis. In complexes 1 and 2 , the (btc)^4– ligand acts as connectors to link metal ions to give a 2D bilayer network of 1 and a 3D metal‐organic framework of 2 , respectively. The differences in the structures are induced by diverging coordination modes of the (btc)^4– ligand, which can be attributed to the difference metal ions in sizes. The results indicate that metal ions have significant effects on the formation and structures of the final complexes. Additionally, the fluorescent properties of the two complexes were also studied in the solid state at room temperature.     

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 Cu^II, 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.     

Two Zinc(II) Coordination Polymers Based on Terphenyl‐2,2′,4,4′‐tetracarboxylate and Dipyridyl Ligands: Syntheses,Crystal Structures,and Luminescent Properties

Two coordination polymers, {[Zn₂(L)(bpy)] · 2H₂O}_n ( 1 ) and [Zn₂(L)(bpe)]_n ( 2 ) [H₄L = terphenyl‐2,2′,4,4′‐tetracarboxylic acid, bpy = 4,4′‐bipyridine, and bpe = 1,2‐bis(4‐pyridyl)ethane], were hydrothermally synthesized under similar conditions and characterized by elemental analysis, IR spectroscopy, TGA, and single‐crystal X‐ray diffraction analysis. Compound 1 has a 3D framework containing Zn–O–C–O–Zn 1D chains. Compound 2 exhibits a 3D framework, which features tubular channels. The channels are occupied by bpe molecules. The differences in the structures demonstrate that the auxiliary dipyridyl‐containing ligand has a significant effect on the construction of the final framework. Additionally, the fluorescent properties of the two compounds were also studied in the solid state at room temperature.