Hydration effects of Al2(MoO4)3 and AlPO4 phases in hydrotreating catalysts studied by solid state nuclear magnetic resonance spectroscopy

Solid state nuclear magnetic resonance spectroscopy of²⁷Al,³¹P, and⁹⁵Mo nuclei was used to investigate species on a NiPMo/Al₂O₃ hydrotreating catalyst calcined at 750 °C before and after rehydration. The Al₂(MoO₄)₃ phase disappeared after rehydration in 100% relative humidity at room temperature. However, almost none of the observed crystalline AlPO₄ reacted with adsorbed water. The results show that the Al₂(MoO₄)₃ phase on an alumina surface reacts easily with moisture unlike Al₂(MoO₄)₃ in the bulk phase. It also suggests that the crystalline AlPO₄ phase is formed under the Al₂(MoO₄)₃ phase or that both species are formed as neighboring islands on the surface of the alumina but have different reactivities toward moisture.     

1H NMR of hydrogen chemisorbed on Pt-Au/Al2O3 catalysts. Evidence for the formation of mixed particles

The evolution of the Pt-Au/Al₂O₃ system with the reduction time can be followed by¹H NMR of chemisorbed hydrogen. When the reduction time increases, the signal with the positive shift, due to hydrogen chemisorbed on pure gold, decreases and disappears completely. At the same time there is a large variation in the negative chemical shift of the hydrogen chemisorbed on the particles containing platinum. This evolution of the NMR spectra demonstrates that mixed Pt-Au particles are formed. Although it appears that after a very long reduction time the platinum covers the gold, the distribution of these two metals in the particles at the atomic scale cannot be determined by this technique.     

Multinuclear magnetic resonance study of equilibria between aluminum(III) and sulfur-containing amino acids in aqueous solutions

Aluminum(III) is generally found in small amounts in living organisms where it interacts with several biomolecules. Low mass biomolecules can form complexes associated with absorption and distribution processes of this toxic ion. However, investigating aluminum(III) complexes in solution poses singular difficulties, because it is highly hydrolyzable. Amino acids constitute possible ligands for aluminum(III). Methionine, cysteine and homocysteine are found in healthy human body. Penicillamine is a drug used in several circumstances, such as in treating metal poisoning. These four biomolecules share similar donor atoms involved in complexation reactions: a carboxylate oxygen, an amine nitrogen and sulfur. In this study, four binary complexes formed by aluminum(III) and amino acids in solution at a metal-to-ligand ratio of 1:1 were analyzed through potentiometry and multinuclear magnetic resonance (¹³C and ²⁷Al). Potentiometry data consistently demonstrated complexion formation. Distributions of species revealed the coexistence of several species in ample pH ranges and pointed out the preferable value to perform the NMR analyses. ¹³C NMR data were used to confirm complexion formation, while ²⁷Al NMR data indicated the geometric arrangement adopted by the complexes. Structures were proposed for each complex.     

Synthesis, X-ray structure and Hg, Se CP MAS NMR studies on the first tris(imidazolidine-2-selone) mercury complex: {Chloro-tris[N-methyl-2(3H)-imidazolidine-2- selone]mercury(II)}chloride

A novel cationic Hg(II) complex has been synthesized with N-methyl-imidazolidine-2-selone ligand. The tris(N-Methyl-imidazolidine-2-selone) mercury(II) complex, [(MeImSe)₃HgCl]⁺Cl⁻ (1), has been characterized by single crystal X-ray analysis and CP MAS ¹⁹⁹Hg and ⁷⁷Se NMR.     

Al_2(SO_4)_3-NH_3·H_2O法大孔拟薄水铝石的制备及其应用

在Al3+浓度0.6 mol·L-1、反应温度60℃和p H=9条件下,研究了硫酸铝滴定氨水(酸滴碱法)、氨水滴定硫酸铝(碱滴酸法)、p H摆动法和并流法成胶方式对共沉淀法制得的拟薄水铝石物化性能的影响。采用X射线衍射、N2吸附-脱附和扫描电镜等对拟薄水铝石进行表征。结果表明,成胶方式对拟薄水铝石物理性能影响显著,采用并流法成胶方式制得的拟薄水铝石比表面积374 m2·g-1,孔容0.89 cm3·g-1,孔径6.4 nm且分布集中,结晶度高,纯度好,能够满足加氢催化剂载体所用拟薄水铝石的物化性能要求。以并流法成胶方式得到的拟薄水铝石制备的Pd/Al2O3催化剂用于裂解汽油双烯烃选择加氢时表现出优异的加氢性能。     

电感耦合等离子发射光谱法测定Pt/Al_2O_3催化剂中的Pt

用电感耦合等离子发射光谱法测定了Al2O3基催化剂中的Pt,考察了基体及所用试剂对Pt测定的影响,发现Al2O3基体、硫酸等对Pt测定均有负干扰,应在标准溶液与基体匹配的情况下进行测定。该方法的检出限为Pt0.10mg/L;样品的加标回收率96%以上。     

A mixed-type of azametallacrown containing [Mn6(pnhz)6(DMF)4(H2O)2] and [Mn6(pnhz)6(DMF)2(H2O)4] constructed by a flexible pentadentate ligand

A mixed-type of azametallacrown based on a flexible pentadentate N-propionyl ligand was reported, which exhibits not only the completely different arrangement of the metal centers but also diversely geometric configurations of the N-terminal ligands, and this complex can further assemble into a novel 3-D supramolecular structure using two different aza18-MC-6 as secondary building units (SBUs) via the intermolecular C–H?π, π–π and C–H?O interactions. Temperature-dependent magnetic susceptibility measurements of the title complex indicate that the complex presents significantly antiferromagnetic coupling among metal centers.     

有机模板硼酸盐[C2H8N][B5O6(OH)4]的合成及发光性能研究

以二甲胺和硼酸为原料,通过水热反应合成有机模板硼酸盐[C2H8N][B5O6 (OH)4],通过单晶X射线衍射对其晶体结构进行分析,该晶体属于单斜晶系,空间群为C2/c,晶胞参数为a=1.3381(75) nm,b=1.1468(56)nm,c=1.7137(92) nm,α=90.032(64)°,β=112.292(82)°,γ=89.988(85)°,V=2.433(2.000) nm3.粉末衍射(PXRD),红外(IR),热重(TGA)以及荧光(PL)等手段对其晶体进行分析表征.在不同温度下对该物质进行热处理,观察其IR和PXRD的变化判断其内部的结构是否能够保持稳定,并通过热重分析进行补充说明.荧光光谱结果表明在经过不同温度热处理后,该物质的发光特性发生明显的变化.实验证实[C2H8N] [B5O6(OH)4]一种可能用在白光LED上的荧光粉.     

三维超分子化合物[Zn(C6H4O2N)2·(H2O)4]n的水热合成及晶体结构

用2-羧基吡啶和六水合氯化锌反应制备了一种新的三维氢键超分子配合物,经X-射线衍射分析确定了单晶结构。该晶体属单斜晶系,P2(1)/n空间群,晶胞参数为:a=9.836(2),b=5.2256(10),c=14.611(3),Mr=381.64,β=90.01(3)°,V=751.0(3)3,Z=2,Dc=1.688Mg.m-3,F(000)=392,μ=1.680mm-1,R=0.0258,wR=0.0612。共收集2159个衍射数据,其中1273个为独立衍射点(Rint=0.0332),可观测点数1139个(I>2σ(I))。结果表明,在组成该超分子体系的基本结构单元[Zn(C6H4O2N)2.(H2O)4]中,Zn(Ⅱ)离子形成六配位的畸变的八面体构型,配合物单元之间通过氢键OH…O相互连接,形成了无限延伸的具有网状结构的三维超分子体系。     

Interactions between fullerene(C60) and poly(ethylene oxide) in their complexes as revealed by high-resolution solid-state C NMR spectroscopy

A series of poly(ethylene oxide) (PEO)/fullerene(C₆₀) complexes are prepared by lyophilization. The intermolecular interaction and molecular motion in the complex are investigated by solid-state ¹³C NMR spectroscopy. An intense C₆₀ signal due to the intermolecular cross-polarization is observed in the ¹³C CP/MAS spectra of the complex samples, indicating a high degree of dispersion of C₆₀s in the complexes. By measuring the ¹³C spin-lattice relaxation times and ¹H transverse relaxation times of the complex sample and by comparing the static ¹³C spectrum of the pure C₆₀ sample with that of the complex sample, it is demonstrated that there exist n-π interactions between the n-orbitals of the PEO ether oxygen and the π-system of C₆₀. The C₆₀ molecules act as physical cross-links in the amorphous region of PEO, which greatly inhibit the mobility of the surrounding PEO chains, while the rapid isotropic rotation of C₆₀ molecules is also reduced to some extent due to the interactions with the polymer chains.     

无机-有机杂化硼酸盐晶体[C_6N_4H_20]_(0.5)[B_5O_6(OH)_4]的合成与表征

介绍了在低温水浴中采用溶剂蒸发法合成硼酸盐晶体[C6N4H20]0.5[B5O6(OH)4]的实验。分别采用X射线粉末衍射仪、热重分析仪和红外分析仪对样品进行了表征,通过对不同大型仪器的使用,能够使学生掌握仪器操作的方法、提高谱图解析的能力。该实验为最新的科学研究成果,知识点新颖,同时将无机合成实验与大型仪器表征有机的结合在一起,不仅能够提高学生的科研能力,还能培养学生的创新思维。     

三维超分子化合物[Zn(C6H4O2N)2·(H2O)4]n的水热合成及晶体结构

用2-羧基吡啶和六水合氯化锌反应制备了一种新的三维氢键超分子配合物,经X-射线衍射分析确定了单晶结构.该晶体属单斜晶系,P2(1)/n空间群,晶胞参数为a=9.836(2)(A),b=5.2256(10)(A),c=14.611(3)(A),Mr=381.64,β=90.01(3)°,V=751.0(3)(A)3,Z=2,Dc=1.688Mg·m-3,F(000)=392,μ=1.680mm-1,R=0.0258,wR=0.0612.共收集2159个衍射数据,其中1273个为独立衍射点(Rint=0.0332),可观测点数1139个(I＞2σ(I)).结果表明,在组成该超分子体系的基本结构单元[Zn(C6H4O2N)2·(H2O)4]中,Zn(Ⅱ)离子形成六配位的畸变的八面体构型,配合物单元之间通过氢键OH…O相互连接,形成了无限延伸的具有网状结构的三维超分子体系.     

Al, N, C and H NMR spectra and negative-ion electrospray mass spectra of the 2:1 aluminium(III) complexes of azo dyes derived from anthranilic acid

The ²⁷Al, ¹⁵N, ¹³C and ¹H NMR spectra in DMSO and mass spectra of 2:1 aluminium(III) complexes (1b–4b) derived from anthranilic acid azo coupling products with 4-tert.butylphenol (1a), 2-naphthol (2a) acetoacetanilide (3a) 3-methyl-1-phenylpyrazol-5-one (4a) were measured and analysed. It was found that the aluminium atom was six-coordinated, being bound to two oxygens and the nitrogen originating from anthranilic acid.     

Comparing Al-SBA-15 Support and Pt/Al-SBA-15 Catalyst: Changes in Al Speciation and Acidic Properties Induced by the Introduction of Pt via Aqueous Medium

Differences between the acidic properties of silicoaluminic Pt-containing catalysts and those assessed on their parent supports have been reported in the literature and attributed to the presence of the metal nanoparticles and to their influence on the acid sites. It is shown here that for mesoporous materials containing various types of Al species, an alternative explanation can be proposed. ²⁷Al NMR spectroscopy, FTIR of adsorbed CO and probe catalytic tests suggest the redistribution of aluminium atoms upon contact of the parent support with the aqueous solution containing the Pt precursor. Upon contact with water and thermal treatment, strong and mild Brønsted sites (Si–O(H)–Al) transform into strong Lewis sites (isolated tetracoordinated Al atoms). As a consequence, it may not be straightforward to deduce the acidic properties of metal-containing catalysts supported on Al-containing mesoporous materials from those of the bare support, because the surface species may differ significantly.     

DNA-Binding Study of Tetraaqua-bis(p-nitrobenzoato)cobalt(II) Dihydrate Complex: [Co(H2O)4(p-NO2C6H4COO)2]·2H2O

The interaction of [Co(H₂O)₄(p-NO₂C₆H₄COO)₂]^· 2H₂O with sheep genomic DNA has been investigated by spectroscopic studies and electrophoresis measurements. The interaction between cobalt(II) p-nitrobenzoate and DNA has been followed by gel electrophoresis while the concentration of the complex was increased from 0 to 14 mM. The spectroscopic study and electrophoretic experiments support the fact that the complex binds to DNA by intercalation via p-nitrobenzoate into the base pairs of DNA. The mobility of the bands decreased as the concentration of complex was increased, indicating that there was increase in interaction between the metal ion and DNA.     

FT-IR studies of decarbonylation and recarbonylation of [Pt3(CO)6] 5 2− supported on dehydrated SiO2

Decarbonylation of [Pt₃(CO)₆]₅ on SiO₂ at 373 K produced [Pt₃(t-CO)₃]₅ species, where all the terminal CO remained. Complete decarbonylation at 423 K was not observed, which led to aggregation at 473 K. The interaction of some Pt with SiO₂ inhibited complete recarbonylation to [Pt₃(CO)₆]₅.     

UV/H2O2氧化联合Ca(OH)2吸收同时脱硫脱硝

在小型紫外光-鼓泡床反应器中,对UV/H₂O₂氧化联合Ca(OH)₂吸收同时脱除燃煤烟气中NO与SO₂的主要影响因素[H₂O₂浓度、紫外光辐射强度、Ca(OH)₂浓度、NO浓度、溶液温度、烟气流量以及SO₂浓度]进行了考察。采用烟气分析仪和离子色谱仪分别对尾气中的NO₂和液相阴离子作了检测分析。结果显示:在本文所有实验条件下,SO₂均能实现完全脱除。随着H₂O₂浓度、紫外光辐射强度和Ca(OH)₂浓度的增加,NO的脱除效率均呈现先大幅度增加后轻微变化的趋势。NO脱除效率随烟气流量和NO浓度的增加均有大幅度下降。随着溶液温度和SO₂浓度的增加,NO脱除效率仅有微小的下降。离子色谱分析表明,反应产物主要是SO₄^2-和NO₃^-,同时有少量的NO₂^-产生。尾气中未能检测到有害气体NO₂。     

配合物[Ni(IDB)_2][C_6H_4(OH)COO]·ClO_4·CH_3CH_2OH·H_2O催化尿素水解的机理及其电化学性质

报道[Ni(H2O)6](ClO4)2·2H2O的合成、晶体结构,单核镍(Ⅱ)配合物[Ni(IDB)2][C6H4(OH)COO]·ClO4·CH3CH2OH·H2O[配体IDB为N,N 二(2 苯并咪唑亚甲基)胺]的电化学性质,探讨标题配合物催化尿素水解的机理。X射线单晶衍射表明,[Ni(H2O)6](ClO4)2·2H2O晶体属单斜晶系,P2(1)/C空间群,化学式:Cl2H16O16Ni,Mr=401.74,晶胞参数:a=0.62383(12)nm,b=1.2464(3)nm,c=0.91845(18)nm,α=90°,β=106.93(3)°,γ=90°,V=0.6832(2)nm3,Z=2,F(000)=412,S=1.079,DC=1.953g/cm3,μ=1.890mm-1。最终因子R[I>2σ(I)]:R1=0.0423,wR2=0.1155;R(全部数据)∶R1=0.0506,wR2=0.1180。结构分析表明,[Ni(H2O)6](ClO4)2·2H2O的镍(Ⅱ)分别与6个H2O配位形成对称的正八面体构型。循环伏安实验说明,标题配合物在DMF溶液中在E1/2=0.884V处经历了一个准可逆的一电子氧化还原过程。     

Molecular Rearrangement of Pyrazino[2,3-c]quinolin-5(6H)-ones during Their Reaction with Isocyanic Acid

New tetrahydropyrazino[2,3-c]quinolin-5(6H)-ones were prepared from 3-chloroquinoline-2,4(1H,3H)-diones and ethylene diamine. In their reaction with HNCO, an unprecedented molecular rearrangement produced new types of hydantoin derivatives. All prepared compounds were characterized on the basis of their ¹H, ¹³C, and ¹⁵N NMR and ESI mass spectra and some were authenticated by X-ray analysis of single crystalline material. A proposed mechanism for rearrangement is discussed in this essay. The CDK and ABL inhibition activity as well as in vitro cytotoxicity of the prepared compounds was also tested.     

Preferential CO oxidation over Pt–SnO2/Al2O3 in hydrogen rich streams containing CO2 and H2O (CO removal from H2 with PROX)

The effects of reaction gases including CO₂ and H₂O and temperature on the selective low-temperature oxidation of CO were studied in hydrogen rich streams using a flow micro-reactor packed with a Pt–SnO₂/Al₂O₃ sol–gel catalyst that was initially designed and optimized for operation in the absence of CO₂ and H₂O. 100% CO conversion was achieved over the 1 wt% Pt–3 wt% SnO₂/Al₂O₃ catalyst at 110 °C using a feed composition of 1.0% CO, 1.5% O₂, 25% CO₂, 10% H₂O, 58% H₂ and He as balance at a space velocity of 24,000 cm³/(g h). CO₂ in the feed was found to decrease CO conversion significantly while the presence of H₂O in the feed increased CO conversion, balancing the effect of CO₂.