Assembly of an eight connected porous Cd(II) framework with octahedral and cubo-octahedral cages: Sorption and luminescent properties

An eight connected 3D porous coordination polymer, {[Cd(BTC)_0.66(BPz)₂] · 6H₂O}_n (1) (BTC = benzene-1,3,5-tricarboxylic acid, BPz = 3,3′,5,5′-tetramethyl-4,4′-bipyrazole) has been synthesized from hydrothermal reaction of Cd(NO₃)₂ · 4H₂O with BPz and BTC. Complex 1 is a thermally stable microporous MOF having cubo-octahedral and octahedral cages as the Supermolecular Building Block (SBB) with an eight connected reo topology. It shows moderate N₂ sorption (101 cm³ g^− 1) at 77 K with a BET surface area of 330 m² g^− 1. Complex 1 also exhibits photoluminescent property in solid state with λ_max at 397 nm.     

Assembly of a water-insoluble strontium metal–organic framework with luminescent properties

A new strontium metal–organic framework, [Sr₂(BTEC)(H₂O)₄]?2H₂O (1) (H₄BTEC = benzene-1,2,4,5-tetracarboxylic acid), has been successfully synthesized by mixing the starting reagents. The single-crystal structure analysis showed that compound 1 displayed three-dimensional structures containing inorganic motifs with two-dimensional layers pillar-connected through organic linkers and forming water-coordinated neutral framework. Further studies revealed that compound 1 was insoluble in water and that it emitted strong luminescence at approximately 437 nm after dehydration.     

Zn-Er heterometallic carboxylate framework based on 3,5-pyrazoledicarboxylic acid with nested sandwich structure and its luminescent property

A three-dimensional 3d-4f heterometallic coordination polymer, {[Er₂Zn(Hpdc)₄(H₂O)₈]·2H₂O}_n (1)(H₃pdc = 3,5-pyrazoledicarboxylic acid), was hydrothermally synthesized and characterized by techniques of single crystal X-ray diffraction, infrared spectra (IR), thermogravimetric analysis(TGA), elemental analysis, powder X-ray diffraction(PXRD), and luminescent measurements. X-ray crystal structure analyses reveal that complex 1 shows a 3D heterometallic framework with nested sandwich-type structure, built by the 2D Er-Hpdc networks, [Zn(Hpdc)₂(H₂O)₂] units, and hydrogen bonds. In addition, the solid-state luminescent property investigation shows that emission lifetime span of the complex was at the microsecond level in the visible region, which is classified as a phosphorescent material. Moreover, when excited at 375 nm, the complex exhibits the characteristic emission ⁴I_13/2 → ⁴I_15/2 of Er(III) at 1514 nm.     

Assembly of an imidazole templated indium-oxalate porous 3D framework with tcj/hc topology: Synthesis,structure and sorption property

A 3D In(III) metal organic framework {[(CH₃)₂NH₂][In₂(Ox)_3.5(Im)]∙H₂O∙DMF}_n (1) (Ox = oxalic acid, Im = imidazole) which is templated by imidazole molecules has been synthesized solvothermally. Compound 1, is an anionic framework with 1D open channels which are filled with (CH₃)₂NH₂⁺, DMF and water molecules. The network exhibits a 3,4-c binodal net with a rare tcj/hc topology. The total solvent accessible volume in the crystal is 43.2%. Sorption studies show that it can adsorb a maximum amount of 47 cm³ g^− 1 of CO₂ gas at 195 K while the uptake of N₂ and CH₄ is negligible.     

Synthesis of thermo- and pH-responsive polysilsesquioxane with carboxylic acid group

The thermoresponsive polysilsesquioxanes containing N-(methoxyethyl)methylamide structures with carboxylic acid groups were newly prepared. In the syntheses of the polysilsesquioxanes, the silane coupling reagent, obtained from the reaction of (3-isocyanatopropyl)trimethoxysilane and (2-methoxyethyl)methylamine, was used for the co-condensation with (3-mercaptopropyl)trimethoxysilane to give the polysilsesquioxane with mercapto group (MMEPSQ). MMEPSQ was employed as the intermediary compound to introduce carboxylic acid group through thiol-ene reaction. The polysilsesquioxane, which was prepared from the reaction of MMEPSQ and methacrylic acid showed the expected amphiphilic and thermoresponsive properties in an aqueous solution with addition of sodium hydroxide. The lower critical solution temperature (LCST) owing to hydrophobic aggregation increased with pH value of the aqueous solution. Furthermoe, the use of MMEPSQ for the reactions with maleic anhydride and successive ring-opening reaction by the amines, which contained pyridine or 15-crown-5-ether ring, enabled the formations of multi-functionalized polysilsesquioxanes. In the case of the polysilsesquioxane containing carboxylic acid groups and pyridine rings, the pyridinium salt structure was favorable to keep an enough solubility in water and the reversible thermoresponsive behavior. The polysilsesquioxane containing the crown ether and carboxylic acid groups, the selective ion recognition property to alkali metal ion was observed.     

通过带有裸露羧酸根的Suzuki反应合成联苯羧酸衍生物的研究

Suzuki偶联反应是合成联苯结构的重要方法之一,本文以溴带芳烃和有机硼酸酯为原料,尝试了带有裸露羧酸根的Suzuki反应,并以62%的产率得到了联苯羧酸衍生物。这为联苯衍生物以及含有联苯结构的生物活性分子的快速生产提供了更为多样化的合成路线,为有效地推动联苯结构化合物的工业化生产做出了贡献。     

Synthesis and characterization of polyanilines doped with several carboxylic acids and with a carboxylic acid equivalent

Polyanilines (PANIs) doped with several organic acids—maleic acid, squaric acid and 2‐propynoic acid—were chemically synthesized in good yields, while PANI doped with 2,6‐dihydroxybenzoic acid did not form under similar polymerization conditions. The resulting PANIs were characterized by spectroscopic and thermal analysis, and it was found that the spectroscopic and thermal properties of these PANIs were affected by the type of dopant ion. Formation of different oxidation states of these PANIs were confirmed by the spectroscopic (UV‐visible and FT‐IR) analysis. Thermogravimetric analysis suggested that PANI doped with maleic acid indicated higher thermal stability than those with the other dopants. The yield and conductivity of PANI doped with maleic acid were found to be higher than those with the other dopants. The PANI doped with 2‐propynoic acid was readily soluble in organic solvents including tetrahydrofuran and dioxane. Copyright © 2005 Society of Chemical Industry     

Effect of substituent carboxylic group on the self-assembly of cadmium coordination polymers: Syntheses,topological analyses and photoluminescence properties

Two coordination polymers, formulated as {[Cd(1,4-BDC)(ppene)]·CH₃CN}_n (1) and [Cd(H₂O)(1,2,4-HBTC)(ppene)_0.5]_n (2) have been synthesized through the solvothermal reactions between Cd(NO₃)₂·4H₂O and 4-pyr-poly-2-ene (ppene) in the presence of 1,4-benzenedicarboxylic acid (1,4-H₂BDC) or its derivative 1,2,4-benzenetricarboxylic acid (1,2,4-H₃BTC). These two compounds were structurally characterized by infrared spectroscopy, elemental analysis, single crystal X-ray diffraction and powder X-ray diffraction. Compound 1 exhibits a three-dimensional two-fold interpenetrating 4¹²6³-pcu network. The coordination network of 2 shows a three-dimensional (4,5)-connected framework with rare (4⁴6²)(4⁴6⁶) tcs topology. Owing to the linkage of hydrogen bonding interactions between protonated carboxylic groups, 2 further displays a three-dimensional (5,5)-connected supramolecular network with an unprecedented Schläfli symbol (4⁸6²)(4⁶6⁴). Thermal stability and photoluminescence properties of 1 and 2 were also investigated.     

Fabrication of porous carbon monoliths with a graphitic framework

Macro/mesoporous carbon monoliths with a graphitic framework were synthesized by carbonizing polymeric monoliths of poly(benzoxazine-co-resol). The overall synthesis process consists of the following steps: (a) the preparation of polymeric monoliths by co-polymerization of resorcinol and formaldehyde with a polyamine (tetraethylenepentamine), (b) doping the polymer with a metallic salt of Fe, Ni or Co, (c) carbonization and (d) the removal of inorganic nanoparticles. The metal nanoparticles (Fe, Ni or Co) formed during the carbonization step catalyse the conversion of a fraction of amorphous carbon into graphitic domains. The resulting carbon monoliths contain >50 wt.% of graphitic carbon, which considerably improves their electrical conductivity. The use of tetraethylenepentamine in the synthesis results in a nitrogen-containing framework. Textural characterization of these materials shows that they have a dual porosity made up of macropores and mesopores (∼2–10 nm), with a BET surface area in the 280–400 m² g⁻¹ range. We tested these materials as electrodes in organic electrolyte supercapacitors and found that no conductive additive is needed due to their high electrical conductivity. In addition, they show a specific capacitance of up to 35 F g⁻¹, excellent rate and cycling performance, delivering up to 10 kW kg⁻¹ at high current densities.     

Structure and luminescent property of a novel one-dimensional organomercury complex

A novel organomercury complex, [Hg₂(μ-CH₃COO)(CH₃COO)(L)]_n (L = 1,3-bis(pyridine-2-ylmethoxy)benzene) 1, has been synthesized. Complex 1 has a one-dimensional chain structure formed by acetate anions bridging Hg(II) atoms in crystallographical c-axis. The orthomercuration of the ligand takes place at C-4 and C-6 of benzene ring rather than C-2 position. It shows intense fluorescent emission by solid-state luminescent analysis.     

Encapsulation of unique anionic carboxylic acid/water cluster chains into channels of a three-dimensional cationic framework

The hydrothermal reactions of CuCl with 1,3-bis(4-pyridyl)propane (bpp), 1,3-benzenedicarboxylic acid (1,3-H₂bdc), and KOH in water afforded {[Cu₈Cl₄(bpp)₈][(1,3-Hbdc)₄(H₂O)_9.5]}_n (1). Single-crystal X-ray diffraction revealed that 1 has anionic [(1,3-Hbdc)₄(H₂O)_9.5]_n^4n? water cluster chains that are encapsulated into the 1D channels of a 3-D [Cu₈Cl₄(bpp)₈]_n⁴ⁿ⁺ cationic framework. The thermal and luminescent properties of 1 in the solid state were also investigated.     

The effect of carboxylic acid group on conductivity of the aromatic polyazomethines and char composites

One of the properties gained by COOH groups of polymer, exists in aromatic polyazomethine (PAM) in the main chain, is the increase in the conductivity. In this study, the PAMs including carboxylic acid in subgroups as condensation polymerization products were obtained. The electrical conductivity of the polymers was enhanced by many orders of magnitude by PAM. The carboxylic acid group increase the electrical conductivity in two ways are: (i) increasing chain flexibility and (ii) allowing movement of the charge carrier more easily along the chain. Additionally, in this study, the polymer composites were obtained using the carbon material (char) derived from the 400°C pyrolysis of waste polyethylene terephthalates. It was observed that conductivity also increased due to char in the composites formed by the PAMs with char. The lowest E_g value of 0.55 eV was determined in poly‐2‐carboxyl‐1,4‐bis[(diphenylether)methylene]phenylenediamine/char composite. The structures of the obtained polymers were confirmed by FTIR, UV–vis, TGA,¹H NMR, and EDX techniques. The molecular weight distribution parameters of the synthesized compounds were determined with the size exclusion chromatography. POLYM. COMPOS., 35:372–380, 2014. © 2013 Society of Plastics Engineers     

Sorption of humic acid on zeolitic tuff: a preliminary investigation

This work involves a study of the interaction of humic acid (HA) with zeolitic (phillipsite+chabazite) Neapolitan yellow tuff (NYT). HA sorption isotherms were carried out on untreated as well as on Li⁺-, Na⁺-, K⁺-, NH₄⁺-, Ca²⁺-, Mg²⁺-, or Ba²⁺-enriched samples. Except for the Li-enriched sample, Langmuir sorption curves fitted the experimental data, allowing the calculation of the maximum HA sorbable amount, Q_max, and the affinity constant between the sorbate and the sorbent, k. The Q_max for the untreated sample was 8512±265 mg kg⁻¹, with k=10.8±1.4 l kg⁻¹. The experimental amounts of HA taken up by the Li-enriched sample were very small (183 to 2322 mg kg⁻¹) and too scattered to be consistently fitted by any significant equation. For other cation enriched-samples, the HA-Q_max amounts ranged from 6583±205 mg kg⁻¹ for the K-treated tuff to 22 029±1065 mg kg⁻¹ for the Mg-treated tuff, whereas the k values ranged from 8.0±1.7 l kg⁻¹ for the Na-treated tuff to 81.4±17.5 l kg⁻¹ for the Ba-treated tuff. The tuff samples enriched by divalent cations took up HA in amounts larger than those observed for the untreated sample; the opposite was true for the monovalent cation-enriched samples. The HA sorption curves on monovalent cation-enriched tuff were scarcely different, within experimental variance, from those observed for the untreated sample. On the contrary, both the Q_max and the k values calculated for the HA sorption on the divalent cation-enriched samples were widely and significantly larger than those of the untreated sample, with the highest Q_max for Mg- and Ca-enriched sample, and the highest k value for the Ba-enriched one. The results demonstrate that enrichment by divalent cations enhances the ability of Neapolitan yellow tuff to take up humic acid, whereas enrichment by monovalent cations reduces it; the results also show that humic acid sorption on tuff must be regarded as a complex phenomenon, occurring as a compromise between the ability of the cations to form stable bridges with the organic matter, and, on the other hand, their specific selective sorption by the tuff.     

Fabrication and microwave absorbing property of WO3@WC with a core-shell porous structure

Special microstructure can significantly improve the microwave absorption property of rare materials. In this paper, porous WC powders were successfully synthesized by spray granulation method. Then, WO₃@WC materials with core-shell porous structure can be prepared after 410 °C heating treatment at different time to form the outer WO₃ oxidation layer. In addition, the microstructure, morphology, phase analysis and electromagnetic property were fully studied by investigating the WC-based materials in different structures. For WO₃@WC core-shell porous materials, when the coating thickness was 2.1 mm, the maximum reflection loss can reach ?19.4 dB at 12.6 GHz, which shows quite good microwave absorbing effects. The core-shell porous structure enhances the original microwave absorption performance due to the multiple reflection reflections and polarizations.     

Synthesis, characterization and luminescent property of a novel zinc(II) 1,2,3,4-tetra(4-pyridyl)thiophene metal–organic framework

A novel metal–organic framework (MOF) [Zn(TPT)(MPDCO)(H₂O)·H₂O]n (TPT = 1,2,3,4-tetra (4-pyridyl)thiophene, MPDCO = 6-methylpyridine-2,4-dicarboxylic acid N-oxide) (1) was obtained via hydrothermal synthesis and characterized by the elemental analysis, IR spectroscopy, TG analysis, luminescent spectroscopy and single-crystal X-ray diffraction analysis. Single-crystal structural analysis reveals that a one-dimensional (1-D) ladderlike MOF is constructed through the mixed ligands, and it is further connected by the intermolecular hydrogen bonds to form a 3-D supramolecular network. Complex 1 exhibits efficient blue luminescence at room temperature, and the framework is stable below 235 °C.     

Assembly of a novel luminescent coordination polymer from europium nitrate and a new semirigid bridging podand

One-dimensional zig-zag coordination polymer has been rationally assembled by the reaction of europium nitrate and a new amide type semirigid bridging podand 1,4-bis{[(2′-m-picolylaminoformyl)phenoxyl]methyl}naphthalene (L). The coordination chains are further linked by the intermolecular hydrogen bonds to form two-dimensional supramolecular layer structure. At the same time, the luminescent properties of the Eu(III) complex were also investigated. Under the excitation, the complex exhibited characteristic emissions of europium ion.     

A lead(II)-orotate coordination polymer with a new coordination mode: Synthesis,structure and luminescent property

A lead(II) orotate complex [Pb(HOr)(H₂O)]_n (1), (H₃Or = orotic acid) was synthesized under hydrothermal condition and characterized by X-ray diffraction, IR, solid-state photoluminescence and thermogravimetric analysis. Lead atom in 1 is in a holodirected eight-coordinated polyhedron and the orotate ligand exhibits a new and unique hexametallic coordination mode. The lead complex shows a 6,6-connected (4⁸, 6⁶, 8)(4¹³, 6²) topology. The complex exhibits photoluminescence at 546 nm (λ_ex = 350 nm).     

Synthesis and characterizations of a paddlewheel-type dirhodium-based photoactive porous metal-organic framework

A paddlewheel-type dirhodium-based, photoactive, porous metal-organic framework, [Rh₂(ZnTCPP)(H₂O)_7.5] ([1]; ZnTCPP = zinc tetra(4-carboxyphenyl)porphyrin), was prepared and characterized via synchrotron X-ray analyses (X-ray powder diffraction, extended X-ray absorption fine structure, and X-ray absorption near-edge structure), elemental analysis, infrared spectroscopy, and N₂ gas adsorption isotherm analysis. Spectroscopic study revealed a drastic decrease in the emission intensity of [1] compared with [ZnTCPP], although features present in the absorption spectra of the two complexes were almost the same. This indicated that [1] underwent the photo-induced intramolecular charge transfer and/or energy transfer from the ZnTCPP moiety to dirhodium moiety.     

Template-free environmentally friendly synthesis and characterization of unsupported tungsten carbide with a controllable porous framework

Tungsten carbide (WC) with controlled pore size distribution was synthesized using a novel “precursor reassembly” method. The precursor crystal was assembled by mixing ammonium metatungstate (AMT) and ammonium carbonate (AC) in distilled water, followed by hydrothermal treatment. The mesostructure, crystal phase, and amount of deposited graphitic carbon can be conveniently tuned by controlling carburizing atmosphere (CO or a CO/H₂ mixture). Moreover, the influence of precursor preparation (AMT/AC mass ratio and hydrothermal temperature) on the materials was also investigated. The resultant materials with low carbon content were mesoporous WCs, which showed high specific surface areas (11.3-20.4 m² g⁻¹) and adjustable pore-size distributions (average pore size: 15.3-22.3 nm). A mechanism for the formation of WC with a controllable porous framework is proposed. Finally, cyclic voltammetry was used to investigate the inference of different mesoporous structure.     

Crystallization kinetics of poly(butylene terephthalate) (PBT): Influence of additives and free carboxylic acid chain ends

Degradation of poly(butylene terephthalate) (PBT) induced by blending time at 260°C leads to an increase of both carboxylic end groups and melt viscosity index and a decrease of the molecular weights. Crystallization kinetics of pure PBT and PBT blended with and epoxide, which was used to reduce the free carboxylic acid concentration, were compared. Lower carboxylic acid concentrations were obtained, but the molecular weights still decreased. The crystallization kinetics of PBT blended with pigments and/or mineral fillers were also studied. Dyes, some of which are known for their nucleation activity, were used for differentiating extruded PBT tubes in optical fiber loose cables. Post‐shrinkage appeared to depend on the type of pigment used. Pigments Concentration, particle size and chimical nature have been correlated to the PBT crystallization kinetics. An increase of the nonisothermal crystallization temperature was observed, more or less important according to the pigment used. Talc and mica were also tested in PBT blends, with and without pigments. Their mucleation activity parameters were measured and compared with those for the pigments. An average value of the crystallization temperature, nearly constant and independent of the Pigment, was obtain controlled shrinkage on industrial products with strict dimension requirements.