化合物[Co(2,2'-bpy)2H2O]12[Mo12V6O42(VO4)][Mo8V8O40(VO4)]3·8H2O的水热合成与晶体结构

用中温水热法合成出一种新的α-Keggin结构化合物[Co(2,2'-bpy)2H2O]12[Mo12V6O42(VO4)][Mo8V8O40(VO4)]3·8H2O,并对其进行了元素分析、IR谱、TGA及X-射线单晶衍射等系列表征.该簇合物属三斜晶系,空间群P-1,a=1.57287(2)nm,b=2.46159(3)nm,c=0.52347(3)nm,α=76.6220(3)°,β=92.078°,γ=79.9390(4) °,V=9.1934(2)nm3,Z=2,Dc=4.642 g·cm-3,μ=4.642mm-1,F(000)=12420,R1=0.0751,wR2=0.1964.化合物中基本构筑单元为三种具有α-Keggin结构的聚阴离子簇,簇与簇之间通过配位阳离子[Co(2,2'-bpy)2H2O]2+桥连成三维结构.化合物中包含少见的六帽α-Keggin结构簇单元.并且在同一晶胞中同时存在聚阳离子和聚阴离子.     

VOPO4⋅2H2O and Fe(H2O) x (VO)1-x PO4⋅2H2O Supported on TiO2 as Catalysts for Oxidative Dehydrogenation of Ethane

The effect of iron substitution on bulk and TiO₂-supported VOPO₄2H₂O on the catalytic performances in oxidative dehydrogenation of ethane has been studied in a fixed-bed reactor at 550 °C. The samples have been characterized by XRD, BET measurements, TPR and ammonia TPD experiments. A uniform dispersion of the active phase on the support has been obtained. Both iron substitution and dispersion on TiO₂ significantly modify redox and acid properties of vanadyl orthophosphate. A good correlation between the acid and redox properties of the catalysts and their catalytic performances has been observed.     

Suppressing fire hazard of poly(vinyl alcohol) based on (NH4)2[VO(HPO4)]2(C2O4)·5H2O with layered structure

Two-dimensional layered ammonium vanadium oxalate-phosphates (AVOPh) with the structural formula of (NH₄)₂[VO(HPO₄)]₂(C₂O₄)·5H₂O are synthesized though a hydro-thermal method, which is dispersed into poly(vinyl alcohol) (PVA) matrix to prepare PVA/AVOPh composites. The results of thermal analysis indicate that AVOPh and PVA have similar decomposition temperature from 280 to 500°C, which is critical for choosing flame retardant. The incorporation of AVOPh significantly improves the thermal stability and flame retardancy of PVA/AVOPh composites that the T_5% value of PVA/2 wt% AVOPh composites is up to 215°C, and the residue of PVA/8 wt% AVOPh composites is enhanced to 16.9%, while those of pure PVA are only 178°C and 2.4%. PVA/4 wt% AVOPh composites can pass V-0 level, and its limiting oxygen index value is up to 32.0%. Furthermore, the peak heat release rate (PHRR) and total heat release (THR) of PVA/AVOPh composites are obviously decreased, which reduced by 43.4% and 43.8% with the addition of 4 wt% AVOPh, compared with those of pure PVA. The excellent thermal stability and flame retardancy are mainly attributed to the uniform dispersion and barrier effect of 2D layered AVOPh, the release of crystal water, ammonia and phosphorus free radicals and the two-phase flame retardant catalytic mechanism of vanadium and phosphorus.     

(NH4)2C2O4·H2O和NH4HC2O4·0.5H2O 单晶的培养研究

利用六次甲基四胺缓慢水解产生的NH3和草酸反应,扩散法培养出(NH4)2C2O4·H2O和NH4HC2O4·0.5H2O两种单晶.     

Vanadyl formate VO(HCOO)2·H2O as a precursor for preparing nanoscale vanadium sesquioxide V2O3

Vanadyl formate monohydrate VO(HCOO)₂·H₂O has been synthesized by a facile two-stage method. The chemical and structural identity of the synthesized compound has been confirmed by X-ray diffraction, thermogravimetry, vibrational and absorption spectroscopy. It was established that during heating in water and ethylene glycol, VO(HCOO)₂·H₂O leads to vanadyl hydroxide VO(OH)₂ and vanadyl glycolate VO(OCH₂CH₂O) being formed. When heated in air or in helium at 300 °C and higher, VO(HCOO)₂·H₂O transforms into vanadium pentoxide or sesquioxide, respectively. VO(HCOO)₂·H₂O was used as a precursor for the synthesis of nanoscale vanadium sesquioxide (with an average particle size of 50 nm), which is stable under the normal conditions and is characterized by a lower metal-insulator transition temperature than the microsized (bulk) compound. The effect of transition temperature reduction for nanoscale vanadium sesquioxide agrees with the lower value of its unit cell volume (V = 296.74 Å³) as compared with that for bulk V₂O₃ (297.7 Å³). The main factor affecting the V₂O₃ particle size is the annealing temperature of precursor in inert atmosphere.     

Synthesis,structure and characterization of (NH4)2[Cu2(H2O)4(NH3CH2COO)2(NH2CH2COO)2]H2V10O28·6H2O

The decavanadate with a novel glycine–glycinato complex of copper (II) in the cationic part, (NH₄)₂[Cu₂(H₂O)₄(NH₃CH₂COO)₂(NH₂CH₂COO)₂]H₂V₁₀O₂₈·6H₂O (1), has been prepared and characterized by elemental analysis, infrared and EPR spectroscopies. The triplet X band EPR spectrum of powdered sample evidenced magnetic interaction between the Cu(II) atoms in the dimeric unit which is probably realized through the bridging water molecules in this part of the complex. A single crystal X-ray diffraction study revealed that the structure of 1 contains cationic copper complex with a rare Cu(H₂O)₂Cu double bridge. In this cation, a simultaneous bidentate N, O– and monodentate O– coordination of glycine to the same central atom was observed for the first time.     

Synthesis,characterization and sorption properties of a porous coordination polymer: Co3(citrate)2(4,4′-bipyridine)4(H2O)2·4(H2O)

A porous coordination polymer, Co₃(citrate)₂(4,4^′-bipyridine)₄(H₂O)₂·4(H₂O) has been synthesized and characterized. It adopts a 3-D framework, built up by parallel [Co₃(citrate)₂]_n chains cross-linked by 4,4^′-bipyridine ligands. The connection leads to hydrophilic cavities filled with water molecules, which interact with the citrate ligands through hydrogen bonds. Dangling 4,4^′-bipyridine ligands are observed in the structure, pointing to cavities. Two equivalents of coordination water and four equivalents of crystallization water molecules can be removed reversibly based on TGA studies.     

Al3(SO4)2(OH)5H2O与α-Al2O3晶须的制备及其生长机制

采用液相沉淀及烧结方法制备了Al3(SO4)2(OH)5H2O与α-Al2O3晶须,样品采用XRD、SEM及G-DTA等对样品物相、形貌及热行为进行了表征,结果表明晶须样品的分散性好,粒度分布均匀、表面光滑,Al3(SO4)2(OH)5H2O与α-Al2O3晶须品质优良.又从“生长基元”角度出发,讨论了Al3(SO4)2(OH)5H2O晶须的形成机制,其生长过程是生长基元是八面体[Al-(OH)6]3-与HSO4-往某一晶面稳定叠合生长的结果,Al3(SO4)2(OH)5H2O晶须经热分解后,其形貌不变,最终变为α-Al2O3晶须.     

A Novel Mixed-Valence Tetranuclear Iron-Oxygen Clusters in the Organically Templated Iron Phosphate [H3N(CH2)2NH3]2 Fe4O(PO4)4 ċH2O

A novel iron phosphate templated with ethylenediammonium cation, [H₃N(CH₂)₂NH₃]₂ Fe₄ O(PO₄)₄H₂O, has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction, thermo-gravimetric analysis, magnetic susceptibility and Mossbauer spectroscopy. The compound crystallizes in the mono-clinic space group C2 with a= 30.3801(5),b= 10.1204(5),c= 10.0977(5) Å, = 107.712(1)°, V = 2957.5(4) ų and Z = 6. The structure contains 5 and 6-coordinated Fe atoms bridged by ₄-oxygen and PO₄ groups to form two types of mixed-valence Fe₄P₄ cubane-like clusters, which are connected via Fe- O- P bonds to give rise to intersecting channels that house the ethylenediammonium cations and water molecules. Room-temperature Mossbauer data confirm the presence of Fe^II and Fe^III.     

[Co(Ⅱ)(H2O)6](C4H4O4)·2C6H12N4·4H2O修饰电极电化学催化谷胱苷肽研究

利用气相沉积法研制了基于TiO2凝胶固定化[Co(H2O)6](C4H4O4).2C6H12N4.4H2O(CoL)修饰电极。研究了该修饰电极对谷胱苷肽(GSH)的催化活性,发现在pH 7.5,0.1 mol/L NaAc-HAc的缓冲溶液中,CoL对电氧化GSH浓度之间有较好的线性关系.线性范围为2×10-6~1×10-4mol/L,检测下限为8×10-7mol/L,相对标准偏差为2.0%(cGSH=5×10-6mol/L,n=6)。应用该法测定生物样品中谷胱苷肽的含量并与紫外分光光度法进行对照,结果一致。     

Hydrothermal synthesis,crystal structure and physical properties of {[Gd(H2O)4(μ2-C6NO2H5)2Gd(H2O)4](μ3-C6NO2H4)2(ZnCl3)2} · 2H2O · 2Cl

A bimetallic 4f–3d tetranuclear complex {[Gd(H₂O)₄(μ₂-C₆NO₂H₅)₂Gd(H₂O)₄](μ₃-C₆NO₂H₄)₂(ZnCl₃)₂} · 2H₂O · 2Cl (1) has been synthesized via hydrothermal reaction and structurally characterized by single-crystal X-ray diffraction. Complex 1 is characterized by a tetranuclear Gd₂Zn₂ structure with the gadolinium and zinc atoms interconnected by isonicotinic acid ligands. The tetranuclear species of {[Gd(H₂O)₄(μ₂-C₆NO₂H₅)₂Gd(H₂O)₄](μ₃-C₆NO₂H₄)₂(ZnCl₃)₂} link to isolated chlorine ions and water molecules via π?π interactions and hydrogen bonds to yield a 3-D supramolecular framework. Photoluminescent investigation reveals that the title complex displays an emission in ultraviolet region. The solid-state diffuse reflectance spectra of 1 reveal the presence of a sharp optical gap of 3.66 eV.     

Synthesis of tributyl citrate catalyzed by Ce(SO4)2·4H2O/ NH2SO3H

研究了柠檬酸与正丁醇在Ce(SO₄)₂·4H₂O/ NH₂SO₃H复配催化剂催化作用下制备柠檬酸三丁酯的工艺条件。实验结果表明Ce(SO₄)₂·4H₂O/ NH₂SO₃H催化合成柠檬酸三丁酯的最佳反应条件为：醇酸摩尔比为4.0∶1,催化剂用量为1.5%（以柠檬酸质量计）,m[Ce(SO₄)₂·4H₂O]∶m(NH₂SO₃H)=2∶1,反应温度为150 ℃,反应时间为7 h,酯化率＞98.5%,精制后产品纯度>99.5%。     

稀土铈盐Ce(SO4)2·4H2O/NH2SO3H催化合成柠檬酸三丁酯

研究了柠檬酸与正丁醇在Ce(SO4)2·4H2O/NH2SO3H复配催化剂催化作用下制备柠檬酸三丁酯的工艺条件。实验结果表明Ce(SO4)2·4H2O/NH2SO3H催化合成柠檬酸三丁酯的最佳反应条件为:醇酸摩尔比为4.0∶1,催化剂用量为1.5%(以柠檬酸质量计),m[Ce(SO4)2·4H2O]∶m(NH2SO3H)=2∶1,反应温度为150℃,反应时间为7h,酯化率>98.5%,精制后产品纯度>99.5%。     

A highly nuclear vanadium-containing tungstobismutate: synthesis and crystal structure of K11H[(BiW9O33)3Bi6(OH)3(H2O)3V4O10]·25 H2O

A novel and large heteropolyanion [(BiW₉O₃₃)₃Bi₆(OH)₃(H₂O)₃V₄O₁₀]¹²⁻ has been synthesized by reaction of sodium metavanadate with Na₉[BiW₉O₃₃]·16H₂O in acetate buffer solutions (at pH 4.8). The present anion has a trilobal structure in which three α-B {BiW₉O₃₃} units are connected to each other by an unique core [Bi₆(OH)₃(H₂O)₃V₄O₁₀]¹⁵⁺. A central bismutate/vanadate-mixed core comprises three sets of two types of the BiO₆ pentagonal pyramid, the edge-sharing VO₅ square-pyramidal triad, and a VO₄ tetrahedron.     

Surface immobilisation of the sandwich type Na14[Fe4(Ox)4(H2O)2(SbW9O33)2]·60H2O polyoxometalate

A functionalised Fe-substituted Keggin Na₁₄[Fe₄(C₂O₄)₄(H₂O)₂(SbW₉O₃₃)₂]·60H₂O type POM termed “Fe₄Ox₄” has been successfully immobilised onto carbon electrode surfaces through the employment of conducting polypyrrole films and the layer-by-layer (LBL) technique. For the POM doped polypyrrole films the redox systems associated with the POM's tungsten-oxo framework was not apparent upon redox cycling, however a reversible redox couple associated with the Fe^III/II redox system was clearly seen within the pH range 2–7. Organised multilayer assemblies were constructed by the employment of the layer by layer (LBL) technique through alternating anionic Fe₄Ox₄ layers and cationic Ru^II metallodendrimers with poly(diallyldimethylammonium chloride) (PDDA) employed as an initial base layer. Stable redox couples associated with both the Fe^III/II and tungsten-oxo framework, for the Fe₄Ox₄ POM, and the Ru^III/II for the metallodendrimer, were clearly observed upon layer construction and redox switching within the pH domain of 2–7. The resulting multilayer assembly showed good stability towards redox cycling. Further investigations into the multilayer assembly were undertaken by determining it is charge transfer resistance using AC-impedance voltammetry. The layer also showed catalytic ability towards the reduction of H₂O₂ at pH 6.5.