A series of metal-organic frameworks constructed with arenesulfonates and 4,4′-bipy ligands

Five transition metal compounds containing arenesulfonates and 4,4′-bipy ligands, namely [Zn₂(N,N′-4,4′-bipy)(N-4,4′-bipy)₂(H₂O)₈](bpds)₂ · 5H₂O (1), [Ag₂(N,N′-4,4′-bipy)₂(bpds)] (2), [Cd(N,N′-4,4′-bipy)(H₂O)₄]₂(4-abs)₄ · 5H₂O (3), [Cu(N,N′-4,4′-bipy) (O-bs)₂(H₂O)₂] · 4H₂O (4), and [Zn(N,N′-4,4′-bipy)₂(H₂O)₂](4,4′-bipy)(bs)₂ · 4H₂O (5) (4,4′-bipy = 4,4′-bipyridine, bpds = 4,4′-biphenyldisulfonate, 4-abs = 4-aminobenzenesulfonate, bs = benzenesulfonate), have been synthesized and characterized by X-ray single crystal diffraction, elemental analyses and TG analyses, in order to investigate the coordination chemistry of arenesulfonates and 4,4-bipy, as well as to construct novel coordination frameworks via mixed-ligand strategy. Compounds 2, 4 and 5 could be obtained via hydrothermal or aqueous reactions. Compound 1 forms a binuclear octahedral metal complex. Compounds 2–4 form polymeric chains. Compound 5 consists of 2D square grids with one intercalated 4,4′-bipy molecule. Weak Ag–Ag interactions are observed in compound 2. These complexes show great structural varieties and there are three different coordination modes observed for both the 4,4′-bipy and the sulfonate ligands.     

New Cu(II)4 and Zn(II)4 complexes: Synthesis, characterization and magnetic and biological studies

Two new isomorphous tetranuclear complexes [Cu₄L₂(4,4′-bipy)₂]·(ClO₄)₄·2CH₃CN·2H₂O (1) and [Zn₄L₂(4,4′-bipy)₂]·(ClO₄)₃·CH₃O·4H₂O (2) have been obtained and fully characterized (where bipy = bipyridine, H₂L = macrocycle is the [2+2] condensation product of 2,6-diformyl-4-fluoro-phenol and 1,4-diaminobutane). They exhibit wheel-like configuration in which two 4,4′-bipy molecules connect two dinuclear [M₂L]²⁺ units. The interactions of the complexes with calf thymus DNA were studied by UV-Vis and CD spectroscopic techniques. The binding constants of 1 and 2 are 2.27 × 10⁶ and 3.89 × 10⁵ M⁻¹, respectively. The magnetic measurement of 1 reveals that there are strong antiferromagnetic coupling (J = -272.6 cm⁻¹) between two Cu(II) ions in the macrocyclic unit and ferromagnetic interaction (j′ = 41.7) between the Cu(II) ions in two adjacent macrocyclic units. Furthermore, the cyclic voltammogram of 1 shows that it undergoes two quasi-reversible processes with the half wave potentials -0.232 and -0.606 V, respectively.     

Four divalent transition metal carboxyarylphosphonate compounds: Hydrothermal synthesis, structural chemistry and generalized 2D FTIR correlation spectroscopy studies

Four divalent transition metal carboxyarylphosphonates, [Ni(4,4′-bipy)H₂L¹(HL¹)₂(H₂O)₂]·2H₂O 1, [Ni₂(4,4′-bipy)(L²)(OH)(H₂O)₂]·3H₂O 2, Mn(phen)₂(H₂L¹)₂3 and Mn(phen)(HL²) 4 (H₃L¹=p-H₂O₃PCH₂-C₆H₄-COOH, H₃L²=m-H₂O₃PCH₂-C₆H₄-COOH, 4,4′-bipy=4,4′-bipyridine, phen=1,10-phenanthroline) were synthesized under hydrothermal conditions. 1 features 1D linear chains built from Ni(II) ions bridging 4,4′-bipy. In 2, neighboring Ni₄ cluster units are connected by pairs of H₃L² ligands to form 1D double-crankshaft chains, which are interconnected by pairs of 4,4′-bipy into 2D sheets. 3 exhibits 2D supramolecular layers via the R₂²(8) ringed hydrogen bonding units. 4 has 1D ladderlike chains, in which the 4-membered rings are cross-linked by the organic moieties of the H₃L² ligands. Additionally, 2D FTIR correlation analysis is applied with thermal and magnetic perturbation to clarify the structural changes of functional groups from H₃L¹ and H₃L² ligands in the compounds more efficiently.     

Syntheses,structures, network topologies and photoluminescence of four Zn(II) and Cd(II) coordination polymers based on 5-carboxyl-1-carboxymethyl-2-oxidopyridinium

5-Carboxyl-1-carboxymethyl-2-oxidopyridinium (H₂CCOP) and a combination of N-donor ligands, such as 4,4′-bipyridine (4,4′-bipy) and 1,10-phenanthroline (phen) with d¹⁰ metal ions Zn(II) and Cd(II) give rise to four coordination polymers, namely, [Zn₂(CCOP)(OH)₂(H₂O)] (1), [Zn(CCOP)(phen)(H₂O)]·H₂O (2), [Cd(CCOP)(H₂O)₂]·3H₂O (3), and [Cd(CCOP)(H₂O)] (4). Polymer 1 features an unusual bilayer motif and forms the final (3,8)-connected 3D topology by hydrogen bonds. Polymer 2 consists of one-dimensional (1D) chains which are further connected with each other via hydrogen bonds to form the final interesting (3,6)-connected rutile network. Polymer 3 is made up of an unusual 2D structure containing cylinder channels in the b axis and features the (4,4)-connected 3D network by hydrogen bonds. Polymer 4 presents an interesting uninodal 4-connected net compared to polymer 3. These four coordination polymers are obtained by evaporation or hydrothermal route and characterized by analytical, spectroscopic, and crystallographic methods. Photoluminescence studies revealed that these four coordination polymers display structure-related fluorescent emission bands (λ_ex = 342 nm) at 361 nm for polymer 1, 404 nm for polymer 2, 367 nm for polymer 3, and 371 nm for polymer 4 in the solid state at room temperature.     

Crystal structures and properties of four coordination polymers constructed from flexible pamoic acid

Four novel coordination polymers constructed from flexible pamoic acid, namely [Co(pam)(4,4′-bipy)]_n·nH₂O (1), [Ni(pam)(4,4′-bipy)(H₂O)₂]_n·2nCH₃CN (2), [Cd(pam)(py)₂]_n·npy (3) and [Mn₂(pam)₂(py)₆(H₂O)₂]_n·2npy (4), (H₂pam = pamoic acid, 4,4′-bipy = 4,4′-bipyridine, py = pyridine), have been synthesized and characterized by elemental analysis, infrared spectra and X-ray crystallography. Complex 1 is a 2-D coordination polymer constructed from chelating bis-bidentate pam and 4,4′-bipyridine bridging ligands. Complex 2 is a 2-D coordination polymer assembled by bis-monodentate pam and 4,4′-bipyridine, where acetonitrile is filled in the rectangle channels. Both 2-D coordination polymers display undulated (4,4) grid layers as sql topology. Complex 3 displays a 1-D polymeric chain using chelating bis-bidentate pam as bridging ligand. Complex 4 exhibits an interesting bis-monodentate pam-Mn(II) 1-D polymeric chain, in which exist two-type six-coordinated manganese centers. Mn(1) is bound to four pyridine ligands, whereas Mn(2) is combined to two pyridine and two H₂O molecules. Their thermal stabilities have been investigated. Cadmium complex 3 displays strong green luminescence with emission maximum at 543 nm.     

Two new supramolecular assemblies based on Keggin-type polyoxometalates through AgO and ππ stacking interactions

Two new supramolecular assemblies based on Keggin-type polyoxometalates, [Ag₃(4,4′-bipy)₂(2,2′-bipy)₂][Ag(2,2′-bipy)₂][{Ag(2,2′-bipy)}HSiW₁₁VO₄₀] (1) and [Ag₃(4,4′-bipy)₂(2,2′-bipy)₂][Ag(2,2′-bipy)₂][{Ag(2,2′-bipy)}PW₁₁VO₄₀] (2) (4,4′-bipy = 4,4′-bipyridine, 2,2′-bipy = 2,2′-bipyridine), have been synthesized under the hydrothermal conditions and structurally characterized by IR, XPS, TG and single-crystal X-ray diffraction. Compound 1 has a 2D layer network structure via weak Ag^...O interactions. Compound 2 is isostructural with compound 1. In addition, the fluorescence of compound 1 is reported.     

Hydrothermal synthesis,characterization and properties of a d10 metal coordination polymer with a layered structure based on carboxyphosphinate ligand, 4,4′-bipyridine and four-coordinated zinc ion

Abstract

Hydrothermal reaction of Zn(NO₃)₂ · 6?H₂O with 2-carboxyethyl(phenyl)phosphinate (H₂L) and 4,4'-bipyridine (4,4′-bipy) led to a novel zinc(II) carboxyphosphinate [ZnL(4,4′-bipy)_0.5]_n (1). The zinc ion is tetrahedrally coordinated by two phosphinate oxygen atoms, one carboxylate oxygen atom, and one nitrogen atom of 4,4′-bipy ligand. The L^2- ligand and zinc ion can be seen as three- and four-connected nodes, respectively. Compound 1 shows a layered network with (3,4)-connected topology. It exhibits a broad blue fluorescent emission band at 459?nm, which can be attributed to 4,4′-bipy intraligand emission as well as to H₂L emission. It is a diamagnetic system between 300?K and 11?K.     

Hydrothermal syntheses, crystal structures and properties of 0-D, 1-D and 2-D organic-inorganic hybrid borotungstates constructed from Keggin-type heteropolyanion [α-BW12O40] and transition-metal complexes

Three novel organic-inorganic hybrid borotungstates {[Ni(phen)₂(H₂O)]₂H(α-BW₁₂O₄₀)}·4H₂O (1), [Cu^I(2,2'-bipy)(4,4′-bipy)_0.5]₂{[Cu^I(2,2′-bipy)]₂Cu^I(4,4′-bipy)₂(α-BW₁₂O₄₀)} (2) and {[Cu^I(4,4′-bipy)]₃H₂(α-BW₁₂O₄₀)}·3.5H₂O (3) (phen=1,10-phenanthroline, 2,2′-bipy=2,2′-bipyridine, 4,4′-bipy=4,4′-bipyridine) have been hydrothermally synthesized and structurally characterized by elemental analyses, IR, UV spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), single-crystal X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and photoluminescence. The structural analysis reveals that 1 consists of a 0-D bisupporting polyoxometalate cluster where two [Ni(phen)₂(H₂O)]²⁺ cations are grafted on the polyoxoanion [α-BW₁₂O₄₀]^5- through two terminal oxygen atoms, 2 shows a 1-D infinite chain constructed from [α-BW₁₂O₄₀]^5- polyoxoanions and {[Cu^I(2,2′-bipy)]₂Cu^I(4,4′-bipy)₂}³⁺ cations by means of alternating fashion, and 3 displays an unprecedented 2D extended structure built by [α-BW₁₂O₄₀]^5- polyoxoanions and -Cu^I-4,4′-bipy- linear chains, in which each [α-BW₁₂O₄₀]^5- polyoxoanion acts as a tetradentate inorganic ligand and provides three terminal oxygen atom and one two-bridging oxygen atom. The presence of Ni^II and W^VI in 1, Cu^I ions and W^VI in 2 and 3 are identified by XPS spectra. The photoluminescence of 2 and 3 are also investigated.     

Ultrasound assisted syntheses of a nano-structured two-dimensional mixed-ligand cadmium(II) coordination polymer and direct thermolyses for the preparation of cadmium(II) oxide nanoparticles

A nano-sized mixed-ligand Cd(II) coordination polymer, {[Cd(bpa)(4,4′-bipy)₂(H₂O)₂](ClO₄)₂}_n (1); bpa = trans-1,2-bis(4-pyridyl)ethane and 4,4′-bipy = 4,4′-bipyridine, has been synthesized by a sonochemical method and characterized by IR and ¹H NMR spectroscopy. Compound 1 grows in one dimension by two different bridging ligands, 4,4′-bipy and bpa. The thermal stability of compound 1 in the bulk form and nano-sized was studied by thermogravimetric (TG) and differential thermal analysis (DTA). The crystallinity of this compound was studied by X-ray powder diffraction and compared with an XRD simulation of the single crystal data. CdO nanoparticles were obtained by direct calcination at 500 °C and decomposition in oleic acid at 200 °C of the nano-sized compound 1. The obtained cadmium(II) oxide nano-particles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).     

Hydrothermal synthesis and structural characterization of two 1-D and 2-D Dawson-based phosphotungstates

Two new Dawson-based phosphotungstates (H₂en)_0.5H[Cu(en)₂(H₂O)]₂{[Cu(en)₂](α₁-P₂W₁₇CuO₆₁)}·8H₂O (1) (en=ethylenediamine) and [4,4′-H₂bpy]₂{[Cu(4,4′-bpy)₃][Cu(4,4′-bpy)₄(H₂O)₂]₂[Cu(4,4′-bpy)][α-P₂W₁₈O₆₂]₂}·6H₂O (2) (4,4′-bpy=4,4′-bipyridine) have been hydrothermally synthesized and structurally characterized. 1 crystallizes in the triclinic space group P−1 with a=11.7626(17), b=13.246(2), c=29.350(5) Å, α=87.355(5), β=79.583(5), γ=66.993(3)°, V=4138.3(11) Å³, Z=2, GOF=1.089, R₁=0.0563 and wR₂=0.1505, whereas 2 belongs to the orthorhombic space group Iba2 with a=22.277(8), b=47.04(2), c=22.153(8) Å, V=23215(17) Å³, Z=4, GOF=1.051, R₁=0.0627 and wR₂=0.1477. 1 consists of a 1-D linear chain structure constructed from monocopper^II-substituted Dawson polyoxoanions, while 2 represents the first 2-D sheet-like structure with a (4,4)-connected topological net built up from plenary Dawson-type polyoxoanions and Cu^II-4,4′-bpy complex cations in polyoxometalate chemistry.     

Synthesis,crystal structure and hydrolysis of a dinuclear copper(II) complex constructed by N2O donor Schiff base and 4,4′-bipyridine: Discrete supra-molecular ensembles vs. oligomers

The tridentate Schiff base ligand, 7-amino-4-methyl-5-aza-3-hepten-2-one (HAMAH), prepared by the mono-condensation of 1,2-diaminoethane and acetylacetone, reacts with Cu(BF₄)₂ · 6H₂O to produce initially a dinuclear Cu(II) complex, [{Cu(AMAH)}₂(μ-4,4′-bipy)](BF₄)₂ (1) which undergoes hydrolysis in the reaction mixture and finally produces a linear polymeric chain compound, [Cu(acac)₂(μ-4,4′-bipy)]_n (2). The geometry around the copper atom in compound 1 is distorted square planar while that in compound 2 is essentially an elongated octahedron. On the other hand, the ligand HAMAH reacts with Cu(ClO₄)₂ · 6H₂O to yield a polymeric zigzag chain, [{Cu(acac)(CH₃OH)(μ-4,4′-bipy)}(ClO₄)]_n (3). The geometry of the copper atom in 3 is square pyramidal with the two bipyridine molecules in the cis equatorial positions. All three complexes have been characterized by elemental analysis, IR and UV–Vis spectroscopy and single crystal X-ray diffraction studies. A probable explanation for the different size and shape of the reported polynuclear complexes formed by copper(II) and 4,4′-bipyridine has been put forward by taking into account the denticity and crystal field strength of the blocking ligand as well as the Jahn–Teller effect in copper(II).     

A two-fold interpenetrating 3D metal-organic framework material constructed from helical chains linked via 4,4′-H2bpz fragments

A 3-connected dia-f-type metal-organic framework compound {[Ag(L)_3/2H₂PO₄]}_n (1) has been synthesized by self-assembly of 4,4′-H₂bpz (L=4,4′-H₂bpz=3,3′,5,5′-tetramethyl-4,4′-bipyrazole) and Ag₄P₂O₇ under hydrothermal conditions. It crystallizes in the tetragonal space group I4₁/acd with a=21.406(4) Å, b=21.406(4) Å, c=36.298(8) Å, Z=32. X-ray single-crystal diffraction reveals that 1 has a three-dimensional framework with an unprecedented alternate left- and right-handed helices structure, featuring a non-uniform two-fold interpenetrated (4.14²) net. Photoluminescent investigation reveals that the title compound displays interesting emissions in a wide region, which shows that the title compound may be a good potential candidate as a photoelectric material.     

Infinite chains constructed from flexible bis(benzimidazole)-based ligands

Two neutral ligands, L¹ · 2H₂O and L² · H₂O, and seven complexes, [Cu(pmb)₂(L¹)] (1), [Cu(pmb)₂(L²)] (2), [Cu(Ac)₂(L²)] · 4H₂O (3), [Cu(4-aba)₂(L²)] (4), [Ag(4-ts)(L¹)(H₂O)] (5), [Ag₂(epes)₂(L¹)] · 2H₂O (6), [Ag(1,5-nds)_0.5(L²)] · 0.5C₂H₅OH · H₂O (7) [where L¹ = 1,1′-(1,4-butanediyl)bis(2-methylbenzimidazole); L² = 1,1′-(1,4-butanediyl)bis(2-ethylbenzimidazole), pmb = p-methoxybenzoate anion; Ac = acetate anion; 4-aba = 4-aminobenzoate anion; 4-ts = p-toluenesulfonate anion; epes = N-(2-hydroxyethyl)piperazine-N′-(2-ethanesulfonate) anion; 1,5-nds = 1,5-naphthalenedisulfonate anion], have been synthesized and characterized by elemental analysis, IR, and single-crystal X-ray diffraction. The L¹ and L² ligands in compounds 1–7 act as bridging ligands, linking metal ions into chain structures. The chains in compounds 3, 4 and 6 interlace with each other by hydrogen bonds to generate 3D supramolecular structures. In compound 5, π–π interactions between adjacent L¹ ligands hold the chains to a supramolecular layer. In compound 7, the sulfonate anions act as counterions in the framework. The thermal stabilities of 3, 6 and 7, and the luminescent properties for 5–7 in the solid states are also discussed.     

Self-assembly of triorganotin(IV) moieties with 2,3,4,5-tetrafluorobenzoic acid and 4,4′-bipy, triphenylphosphine oxide or phen: Syntheses, characterizations and supramolecular structures

A series of triorganotin (IV) complexes with 2,3,4,5-tetrafluorobenzoic acid and mixed-ligands of the types: R₃Sn(O₂CC₆HF₄)_m · L (m = 1, L = 0, R = Ph 1; m = 1, L = Ph₃PO, R = Ph 4, Me 5), [R₃Sn(O₂CC₆HF₄)]_m · L (m = 2, L = 4,4′-bipy, R = Ph 2, Me 3; m = n, L = 0, R = Me 6), and [R₃Sn(O₂CC₆HF₄) · (H₂O)]_m · L · C₂H₅OH (m = 2, L = Phen, R = Ph 7, Me 8), (4,4′-bipy = 4,4′-bipyridyl; Phen = 1,10-phenanthroline), have been synthesized by the reaction of triorganotin chloride and 2,3,4,5-tetrafluorobenzoic acid in the presence of mixed-ligands: 4,4′-bipy, triphenylphosphine oxide, or phen. All complexes were characterized by elemental analysis, IR, ¹H, ¹³C, ¹¹⁹Sn NMR spectroscopy analysis. Except for 5 and 8, all the complexes were also characterized by X-ray crystallography.     

Synthesis,spectral, thermal and BVS investigations on ZnS4N^N/N coordination environment: Single crystal X-ray structures of bis(dibenzyldithiocarbamato)(N^N)Zinc(II) complexes (N^N = 1,10-phenanthroline,tetramethylethylenediamine and 4,4′-bipyridine)

The current paper describes the synthesis and spectral investigations on the adducts of [Zn(dbzdtc)₂] (1) with 1,10-phen (2), tmed (3), 2,2′-bipy (4) and 4,4′-bipy (5) (where, dbzdtc = dibenzyldithiocarbamate anion, 1,10-phen = 1,10-phenanthroline, tmed = tetramethylethylenediamine, 2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridne) and single crystal X-ray structures of [Zn(dbzdtc)₂(1,10-phen)] (2) and [Zn(dbzdtc)₂(tmed)] (3) and [Zn(dbzdtc)₂(4,4′-bipy)] (5). ¹H and ¹³C NMR spectra of 1,10-phen, tmed, 2,2′-bipy and 4,4′-bipy adducts were recorded. ¹H NMR spectra of the complexes show the drift of electrons from the nitrogen of the substituents forcing a high electron density towards sulfur via the thioureide π-system. In the ¹³C NMR spectra, the most important thioureide (N¹³CS₂) carbon signals are observed in the region: 206–210 ppm. Fluorescence spectra of complexes (2) and (4) show intense fluorescence due to the presence of rigid conjugate systems such as 1,10-phenanthroline and 2,2′-bipyridine. The observed fluorescence maxima for complexes with an MS₄N₂ chromophore in the visible region are assigned to the metal-to-ligand charge transfer (MLCT) processes. Single crystal X-ray structural analysis of (2) and (3) showed that the zinc atom is in a distorted octahedral environment. Bond Valence Sum was found to be equivalent to 1.865 for (2), 1.681 for (3) supporting the correctness of the determined structure. BVS of (3) deviates from the formal oxidation number of zinc due to the non-aromatic, sterically hindering tetramethyl bonding end of tmed. Thermal studies on the compounds show the formation of Zn(NCS)₂ as an intermediate during the decay.     

Syntheses, crystal structures and photoluminescence properties of three novel organically bonded indium selenates or selenites

Three new organically bonded indium(III) selenates or selenites, namely, In₂(2,2′-bipy)₂(SeO₄)₃(H₂O)₂·2H₂O (1), In₂(2,2′-bipy)₂(SeO₄)(C₂O₄)₂·0.5H₂O (2) and In₂(2,2′-bipy)₂(SeO₃)₂(C₂O₄) (3) (2,2′-bipy=2,2′-bipyridine) have been synthesized by hydro/solvothermal reactions by using the in situ ligand synthesis technique (2 and 3) and structurally characterized. The structure of compound 1 features a dimer composed of two InO₄N₂ octahedra bridged by three SeO₄ tetrahedra via cornering sharing. The structure of compound 2 shows a 2D inorganic-organic hybrid layer in which the indium (III) ions are bridged by both selenate and oxalate anions, whereas the structure of compound 3 possesses a 2D inorganic-organic hybrid layer composed of the indium (III) ions interconnected by both selenite and oxalate anions. The adjacent layers are further interconnected via π…π interactions between the bipy ligands. Compound 1 displays an intra-ligand luminescent emission band at λ_max=360 nm whereas compounds 2 and 3 both exhibit intra-ligand luminescent emission bands at λ_max=389 nm.     

Various coordination architectures constructed from N-[(carboxyphenyl)-sulfonyl]glycine: Structural variation via ligand isomerism effects and metal-directed assembly

Using Cu(II), Mn(II) or Co(II) salt and the flexible ligands, N-[(4-carboxyphenyl)-sulfonyl]glycine (H₃L₁) and N-[(3-carboxyphenyl)-sulfonyl]glycine (H₃L₂), a series of new coordination polymers, [Mn(phen)(H₂O)₄][HL₁] (1), [Co₃(L₁)₂(bipy)₃(H₂O)₆]_n·8nH₂O (2), [Cu₄(L₁)₂(OH)₂(bipy)₄]_n·12nH₂O (3), [Na(H₂L₁)(H₂O)]_n (4), [Mn₂(HL₂)₂(dpe)₃(H₂O)₂]_n·ndpe (5), (phen = 1,10-phenanthroline, bipy = 4,4′-bipyridine, dpe = 1,2-di(4-pyridyl)ethylene), varying from 0D to 3D, have been synthesized and structurally characterized. Compound 1 has a [Mn(phen)(H₂O)₄]²⁺ cation and a HL₁²⁻ anion. Compound 2 features a new 1D triple chain, based on octahedral cobalt atoms bridged by bipy molecules and terminally coordinated by two H₃L₁ ligands. Compound 3 has a 2D layered structure, constructed from new alternating chains where H₃L₁, hydroxyl and water molecules simultaneously act as bridging ligands. Compound 4 possesses a bilayer structure in which two adjacent layers are pillared by H₃L₁ ligands into a 2D bilayer network. Compound 5 is a unique 3D coordination polymer in which each Mn center binds two trans-located dpe molecules. The thermal stability as well as magnetic properties of 5 was also studied. This work and our previous work indicate that the positional isomer of the anionic N-[(carboxyphenyl)-sulfonyl]glycine is important in the construction of these network structures, which are also significantly regulated by the metal centers.     

Step by step palladium mediated syntheses of new 2-(pyridin-2-yl)-6-R-nicotinic acids and esters

Taking advantage of palladium peculiar “rollover” C,N cyclometallation, it is possible to promote C(3) functionalization of 6-alkyl-substituted-2,2′-bipyridines. The carbonylation reaction of rollover species [Pd(Lⁿ)Cl]₂, (HL¹ = 6-isopropyl-2,2′-bipy, 1; HL² = 6-neopentyl-2,2′-bipy, 2; HL³ = 6-ethyl-2,2′-bipy, 3; HL⁴ = 6-methyl-2,2′-bipy, 4) allowed the synthesis of 2-(pyridin-2-yl)-6-alkyl-nicotinic acids or esters. These nicotinic derivatives are extremely rare and, as far as we know, quite unreported in the case of the 6-substituted molecules.     

Characterization of three new divalent zinc coordination polymers involving fluorinated carboxylate tecton via the modulation of heterocyclic N-donor co-ligands

Three new fluorous coordination polymers with a fluorinated carboxylate tecton and N-donor co-ligands, {[Zn₂(hfipbb)₂(phen)₂]·2H₂O}_n (1), [Zn₂(hfipbb)₂(bipy)(H₂O)]_n (2), and [Zn₅(hfipbb)₄ (Hhfipbb)₂ (bpp)]_n (3), [H₂hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid), phen = 1,10-phenthroline, bipy = 4,4′-bipyridine, and bpp = 1,3-bi(4-pyridyl)propane], have been prepared and characterized by elemental analysis, IR spectra, and X-ray diffraction. Compound 1 exhibits a 3D supramolecular network assembled from two independent 1D chain motifs [Zn(hfipbb)(phen)] through π?π stacking, and C-H?F and O-H?O interactions. Compound 2 features 2D undulating layer structure with 4⁴-sql network. Whereas, in compound 3, pentanuclear [Zn₅(η²-O)₂(μ²-η¹:η¹-CO₂)]²⁻ cores are bridged by hfipbb²⁻ and bpp ligands into a 3D 6-connected sxd framework with a point symbol of (3³·4⁶·5⁵·6). The diverse arrangements of the compounds show the modulation of the heterocyclic N-donor co-ligands can suitably mediate the coordination requirement of metal centers as well as the binding modes of fluorinated carboxylate tecton, which consequently generate diverse crystalline architectures. In addition, the properties of thermogravimetric analysis, X-ray powder diffraction, and photoluminescent behaviors of the compounds have also been discussed.