Insight into hexanuclear peroxotantalum complexes:synthesis,characterization,and efficient catalyst for amidation reaction

Polyoxometalates(POMs),large oxoanions of the group 5 and 6 elements,attract attention due to their use as oxidation-stable catalysts and ligands.Different from the well-known V,Mo,and W POMs,the group V POMs of Ta assemble and are stable only in highly alkaline solution rather than acidic solution.In this paper,we successfully synthesized and structurally characterized two unprecedented peroxotantalum-containing clusters,KNa_(2)[HSe_(2)(TaO_(2))_(6)(OH)_(4)(H_(2)O)_(2)O_(13)]·15H_(2)O(1)and Cs_(2)K_(1.5)Na_(1.5)[Se_(4)(TaO_(2))_(6)(OH)_(3)O_(18)]·17H_(2)O(2),which comprises a 6-peroxo-6-tantalum core stabilized by two and four selenite centers,respectively.The simple,one-pot synthesis of 1 and 2 involving addition of sodium selenite into the acidified hexatantalate aqueous solution in the presence of hydrogen peroxide could represent a general procedure for incorporating heteroatoms into peroxo-polyoxotantalate species,thus opening new possibilities for this emergent branch of polyoxotantalate chemistry.Moreover,the catalytic properties of these two compounds were investigated using succinic anhydride and phenylamine as the model substrate,and compound 2 presents excellent catalytic activity in the amidation reactions of anhydrides and amines.

Synthesis and biological evaluation of new peroxo-bridged diosgenin derivatives

Objective： In order to find lead compound with anti-HBV activity from peroxo-bridged diosgenin deriva- tives obtained with Eosin Y as the photosensitizer. Method： Eosin Y was used as the photosensitizer to activate the oxygen in the air to synthesize novel diosgenin derivatives with peroxo-bridge. The structures of synthesized compounds were identified by NMR and HR-MS. Their cytotoxicity and antihepatitis B activity were evaluated via MTS assay and ELISA method, respectively. Results： Six diosgenin derivatives were synthesized, three of which contained peroxo-bridge, and their structures were confirmed by spectroscopy. It showed that 5a,8a-peroxo-6-alkenyl-diosgenin （7） could suppress the production of HBsAg on transfected HepG2.2.15 cells at low-toxic concentration and the in- hibition rate on HepG2.2.15 cells was 18.28% at 12.50 μg/mL, better than that of 3TC （7.30% at 12.50 μg/mL） and others. Conclusion： Due to its lower cytotoxicity and potential anti-hepatitis B activity, compound 7 could be developed as the promising candidate of anti-hepatitis B drug. It also indicated that the peroxo-bridged derivatives had potential biological values for developing clinical agents.

Diperoxo Complexes of Vanadium（V） Containing Mannich Base Ligands

The vanadium（V） peroxo complexes containing Mannich base ligands having composition Na[VO（O2）2（L-L）]·H2O [where L-L=morpholinobenzyl acetamide （MBA）, piperidinobenzyl acetamide （PBA）, morpholinobenzyl benzamide （MBB）, piperidinobenzyl benzamide （PBB）, morpholinomethyl benzamide （MMB）, piperidinomethyl benzamide （PMB）, morpholinobenzyl formamide （MBF）, piperdinobenzyl formamide （PBF）] have been reported. The complexes have been prepared by stirring vanadium pentoxide with excess of 30% aque- ous-H202 followed by treatment with ethanolic solution of the ligand and finally maintained the pH of the reaction mixture by adding dilute solution of sodium hydroxide. The synthesized complexes have been characterized by various physico-chemical techniques, via elemental analysis, molar conductivity, magnetic susceptibility measure- ments, infra red, electronic, mass, ~H NMR spectral and TGA/DTA studies. These studies revealed that the synthesized complexes are uni-univalent electrolytes and diamagnetic in nature. The ligands are bound to metal in a bi- dentate mode through carbonyl oxygen and the ring nitrogen. Thermal analysis result provides conclusive evidence for the presence of one molecule of lattice water in the complexes. Mass spectra confirm the molecular mass of the complexes.

A novel manganese(Ⅲ)-peroxo complex bearing a proline-derived pentadentate aminobenzimidazole ligand

Manganese(Ⅲ)-peroxo complexes are invoked as key intermediates in the enzymatic cycles of Mncontaining enzymes, and the synthesis of reactive manganese(Ⅲ)-peroxo complexes with rationally designed ligand has been of great interest in the communities of bioinorganic and biomimetic chemistry.Herein, we designed a novel pentadentate aminobenzimidazole ligand and obtained its manganese(Ⅱ)complex, which was successfully applied in the synthesis of a reactive manganese(Ⅲ)-peroxo complex by treatment with hydrogen peroxide in the presence of triethylamine. The manganese(Ⅲ)-peroxo complex was well characterized with various spectroscopic techniques, including ultraviolet-visible(UV-vis)spectrophotometry, coldspray ionization time-of-flight mass spectrometry(CSI-TOF MS), and continuous wave electron paramagnetic resonance(CW-EPR) spectroscopy. Besides, its reactivity in aldehyde deformylation was investigated, demonstrating second-order kinetics in the reaction with 2-phenylpropionaldehyde and affording acetophenone as the sole product.

催化氧化法制备双环戊二烯二环氧化物

以过氧化氢为氧源,过氧化磷钨酸盐为催化剂,在水相/有机相两相体系中进行有效的双环戊二烯环氧化反应,避免了用过酸法造成的废酸对环境的污染及环氧化合物的酸性开环。对比了3种不同的季铵盐与磷钨酸制成的催化剂、溶剂、反应温度、催化剂用量及不同浓度的过氧化氢水溶液对双环戊二烯环氧化反应的影响,得到了制备双环戊二烯二环氧化物的最佳条件:以十六烷基氯化吡啶与磷钨酸制成的催化剂为相转移催化剂,其投料量为:催化剂∶双环戊二烯=0.004∶1(摩尔比),以1,2-二氯乙烷为溶剂,H2O2(w=0.5)为氧源。

针状TiO_2锐钛矿晶粒溶胶的制备、结构及形成机理研究

0引言TiO2薄膜能在紫外线的照射下发生光催化反应,将有机物分解为CO2和水,可用于清除有机物、杀菌、消毒、处理污水等,同时由于TiO2薄膜的超亲水性使其具有自洁去污、易清洗、防水雾等功能,引起了广泛的关注[1,2].

离子液体中过氧钨配合物催化氧化燃油脱硫

合成了一种含D,L-丙氨酸配体的钨的过氧配合物WO(O2)2.2C3H7NO2.H2O催化剂。以WO(O2)2.2C3H7NO2.H2O/[Bmim]PF6/H2O2体系为研究模型,考察了反应时间、温度和催化剂用量等因素对燃油脱硫率的影响。结果表明,在70℃反应2 h,n(H2O2)∶n(二苯并噻吩)∶n(催化剂)=30∶10∶1,离子液体用量1mL,模型油中二苯并噻吩脱除率在[Bmim]BF4、[Omim]BF4、[Bmim]PF6和[Omim]PF6中分别为97.3%、96.7%、98.7%和99.0%。实验结果进一步表明,离子液体萃取耦合催化氧化脱硫法能实现深度脱硫,且该方法优于仅用离子液体萃取脱硫或不使用离子液体的催化氧化脱硫法。

过氧氨三乙酸钛配合物分子前体热分解制备纯钛基复氧化物

在pH =2 5～ 4 0的条件下 ,以四氯化钛、过氧化氢和氨三乙酸为原料反应得到四种过氧酸钛配合物 (NH4) 4 [Ti2 O (O2 ) 2 (ta) 2 ]·4H2 O (1) ,K4[Ti2 O(O2 ) 2 (ta) 2 ]·6H2 O (2 ) ,Sr2 [Ti2 O(O2 ) 2 (ta) 2 ]·10H2 O (3 )和Ba2 [Ti2 O(O2 ) 2 (ta) 2 ]·10H2 O (4 )(H3 ta =C6H6O6N) .配合物的EA ,UV vis,IR和X射线单晶分析表明它们含有相同的双核过氧氨三乙酸钛的阴离子结构 ,钛原子与过氧基团、四齿氨三乙酸和桥氧七配位 .3和 4中的阳离子锶和钡分别与周围的水分子和羧基氧形成九配位和十配位 .配合物 1,3和 4在空气中 60 0℃分解 ,XRD分析表明分别得到金红石型TiO2 ,SrTiO3 和四方BaTiO3 纯相 .

溶液pH值及钨前驱体影响含钨过氧物种结构的Raman光谱研究

识别水溶液体系中含过渡金属W ,Mo的过氧物种结构是探索烯烃、醇及醛等与双氧水催化选择氧化反应机理的关键所在 ,本研究借助高灵敏度的共焦显微Raman光谱表征手段 ,考察了Na2 WO4,(NH4) 10 [H2 W12 O42 ]和H3 PW12 O40 三种含钨前驱体在不同pH值条件下与过量双氧水作用产生的主要过氧物种的结构特征 ,推测在酸性较强 (pH <2 3 )的条件下三者产生的主要过氧物种结构相同 ,可能是单核式的 [WO2 (O2 ) 2 (H2 O) ] 2 -,而二聚态或多聚态的过氧物种几乎不存在于体系中 ;此外 ,还首次建立了通过Raman光谱来半定量测定双氧水浓度的分析方法 ,并尝试用于双氧水催化分解的动力学研究中 .

TS-1/H_2O_2催化活性中心结构及活性预测

应用密度泛函理论,研究钛硅分子筛TS-1在H2O2水溶液中的钛氧活性中心结构及稳定性.计算在B3LYP/6-31G（d,p）理论水平进行.通过结构设计和优化,考察了4种活性氧结构在6个不同位点的生成能.结果表明在T10位,稳定性顺序为Ti-η^1（OOH）〉Ti-η^2（OOH）H2O,而其他T位都是Ti-η^2（OOH）H2O〉Ti-η^1（OOH）.吸附一个H2O分子后,都生成更为稳定的六配位钛氧络合物Ti-η^2（OOH）H2O和Ti-η^1（OOH）H2O.Ti-η^2（OOH）物种的活性氧带有更高的正电荷.在Ti-η^1（OOH）和Ti-η^2（OOH）活性中心上乙烯环氧化活化能垒分别为101和37kJ/mol.

过氧改性纳米TiO_2溶胶的制备及其光催化性能

以硫酸氧钛为钛源,过氧化氢为络合剂,采用低温水热法制备了过氧改性纳米TiO2溶胶,并对制备过程中的影响因素进行了研究,同时,通过甲醛废水模型体系考察了溶胶的光催化活性。采用X射线衍射、透射电镜、紫外-可见漫反射光谱等测试手段对TiO2进行了表征。结果表明,当水解反应pH值为8.0,硫酸氧钛浓度为0.10 mol/L,陈化时间为24 h,Ti4+/H2O2物质的量比为1∶4,水热反应温度和时间分别为100℃和6～8 h时,可制得直径20nm、长30 nm,结晶良好的锐钛矿过氧改性纳米TiO2和分散均匀的溶胶。经紫外光和太阳光光照180 min后,过氧改性纳米TiO2溶胶对甲醛的降解率分别为95.3%和31.8%,优于相同条件下P25的光催化性能(69.7%和21.1%)。

改进型过氧钼酸法制备无定形MoO_3薄膜

通过金属钼粉与H2O2反应制得过氧钼酸溶胶液后,减压蒸馏除去过氧钼酸溶液中的溶剂水和过量的H2O2,再加入无水乙醇作为溶剂,采用浸泽-提拉法成功地在玻璃表面制备了平整均匀的无定形MoO3薄膜.并通过热分析和X射线衍射分析等对MoO3薄膜的制备机理进行了探讨.

过氧多酸盐[NBu_4]_3[M(O_2)W_5O_(18)]的合成及表征

过渡金属过氧化合物是一类性能良好的催化剂，在有机合成中得到广泛的应用［１，２］．过氧多酸催化过氧化氢氧化有机物的反应，近年来倍受重视［３～５］．文献中对过氧多酸的报道多以钨、钼为主［６］，而性质相近的铌、钽报道则较少［７］．本文合成了组成为［（Ｃ４Ｈ...

低温制备锐钛矿TiO2溶胶水溶液

利用过氧化的方法低温制备锐钛矿相TiO2溶胶水溶液，其制备过程由4个步骤组成：利用新制备的正钛酸沉淀得到过氧化钛溶液；利用氨水溶液沉淀过氧化钛得到过氧化钛水合物；利用阳离子交换树脂除去杂质NH4^＋；得到的溶液于100℃下密闭加热5h得到最终产物。XRD和FTIR结果表明，可以通过此法在低温下合成稳定的锐钛矿型TiO2溶胶水溶液，而且在制备过程中不会引入任何杂质。TiO2溶胶水溶液的光催化活性通过光催化降解丙酮来表征，结果表明其光催化表观反应速率常数相对P25大0．9×10^-3min^-1。

光催化二氧化钛溶胶的制备

以TiOSO_4为原料、氨水为沉淀剂、H_2O_2为络合剂合成出含有针状锐钛矿晶粒的TiO_2溶胶,该溶胶具有光催化活性。用XRD、TEM等对产物结构和形貌进行了表征。结果表明钛酸沉淀pH值、H_2O_2的加入量、回流时间对二氧化钛溶胶光催化效果有影响。当PTA回流4.75 h所得的RS-4.75的光催化效果最好,在可见光下对甲基橙降解率为52.8%。在PTA溶胶回流过程中增加冷却过程,相对于无冷却过程,材料的光催化性能得到了提高。PTA先回流3 h,溶胶冷却至室温,再回流1 h的溶胶的甲基橙降解率为48%,高于RS-4溶胶的光催化性能。

[N(CH_(3))_(4)]4[Mo_(10)O_(18)(OH)_(4)(O_(2))_(10)(O_(2))_(2)]·6H_(2)O的合成、晶体结构及表征

以质量分数30%过氧化氢为氧化剂,钼酸铵和四甲基氯化铵为原料,室温下采用常规的水溶液法成功制备了一种含有过氧与超氧基团的十核钼酸四甲基铵盐[N(CH_(3))_(4)]4[Mo_(10)O_(18)(OH)_(4)(O_(2))_(10)(O_(2))_(2)]·6H_(2)O,并对其进行了元素分析、红外光谱、紫外光谱表征及X线单晶结构分析.该化合物属于单斜晶系,P21/c空间群,a=1.443(16)nm,b=1.168(12)nm,c=1.693(17)nm,β=99.32(3)°,V=2.814(5)nm^(3),Z=2,Dc=2.441 g/cm^(3),R_(1)=0.0356,wR_(2)=0.1050(I>2,GOF=1.087.其阴离子呈中心对称结构,包含2个键长为0.1145 nm的超氧基团和10个键长为0.1435~0.1481 nm的经典过氧基团.此化合物溶于水不稳定,但在室温下能稳定存在于固态,并能迅速将I-氧化成单质I2,表明了该化合物由于结构中过氧和超氧基团的存在而具有强氧化性.

钼过氧配合物催化过氧化氢氧化环己醇的研究

采用钼酸铵与合氧有机配体原位形成的络合物作为催化剂，以质量分数30％过氧化氢催化氧化环己醇合成环己酮。考察了草酸、水杨酸、苯甲酸、乙酸和丁二酸5种不同的配体对环己醇氧化反应的催化作用，并探索反应时间、反应温度和催化剂用量对环己酮收率的影响。研究结果表明，以草酸为配体时催化效果最好，环己酮收率最高，可达85％。催化氧化反应的最佳条件：Mo与草酸配体物质的量比=1：1，反应温度（85-90）℃，反应时间6h。

甘氨酸过氧化钼配合物的合成与表征

以三氧化钼和甘氨酸为原料,采用固液相法制得了甘氨酸过氧化钼(Ⅵ)配合物,并用元素分析、紫外光谱、红外光谱、X射线粉末衍射和热重分析等方法对产物组成和结构进行了表征。结果表明,所合成配合物的组成为[MoO(O2)2(C2H5NO2)].H2O,中心原子钼(Ⅵ)与1个桥氧基氧原子、两个双齿配位的过氧根的4个氧原子、1个甘氨酸中的羧基氧原子形成了六配位的化合物,X射线粉末衍射数据指标化计算证实其晶体结构属于单斜晶系,晶胞参数为:a=1.776 3 nm,b=1.597 2 nm,c=1.967 0 nm,β=89.15°。

钨、钼羧酸合过氧配合物的合成及性质研究

引进能和钨、钼形成稳定的五元环的羧酸类配体（即：草酸、酒石酸、柠檬酸、苹果酸等），制得了十种新的稳定的钨、钼羧酸合过氧配合物；（ＮＨ４）２［ＭＯ（０２）２（Ｃ２Ｏ４）］（Ｍ＝Ｗ或Ｍｏ）；（ＮＨ４）［ＭＯ（Ｏ２）２Ｌ］·ＺＨ２Ｏ（Ｌ＝酒石酸根、柠檬酸根、苹果酸根）和（ＮＨ４）４［Ｍ２Ｏ２（Ｏ２）４（Ｃ２Ｈ２Ｏ５）］４Ｈ２Ｏ测定了这些过氧配合物固体的Ｒａｍａｎ和ＩＲ光谱以及水溶液的Ｒａｍａｎ光谱，并对配位结构进行了探讨，研究了这些过氧配合物的热稳定性．

用核磁共振氢谱法研究胸腺嘧啶与过氧化钒配合物的光照射反应

利用核磁共振氢谱的方法,研究在单线态氧的作用下,胸腺嘧啶残基(包括胸腺嘧啶(T)、胸腺嘧啶脱氧核苷(dT)和胸腺嘧啶脱氧核苷酸(TMP))的分解产物。胸腺嘧啶残基与过氧化钒配合物的光照射反应,由过氧化钒配合物光分解所产生的单线态氧使胸腺嘧啶碱基发生了光氧化反应,可能的反应产物通过核磁共振氢谱进行了测定。