Influence of Coordination Geometry on the Ring Opening of Benzoxazine: Oxidovanadium(V), Dioxidomolybdenum(VI) and Dioxidotungsten(VI) Complexes of Benzoxazine Based Ligands and their Bio Inspired Catalytic Applications

Mono benzoxazine appended N-capped amino bis(disubstitutedphenol) ligands [ II ( a–c )] upon reaction with V^VO(OEt)₃ in a 1 : 1 molar ratio in EtOH/MeOH give [{V^VO}en(3,5-dtbb)₃] ( 1 ), [{V^VO}en(3-tb,5-mb)₃] ( 2 ) and [{V^VO}en(3,5-dmb)₃] ( 3 ). During the reaction, the benzoxazine ring opens with the loss of methylene group and the newly formed ligands, N,N-bis(2-hydroxy-3,5-disubstitutedbenzyl)-N’-2-hydroxy-3,5-disubstituted benzyledene-1,2-diaminoethane [ III ( a–c )], behave as tribasic pentadentate in these complexes. Under similar conditions, when [M^VIO₂(acac)₂] (M=Mo or W; Hacac=acetylacetone) reacts with II ( a–c ), these ligands retain their identity and form cis-[M^VIO₂] complexes, [{Mo^VIO₂}{en(3,5-dtbb)₂(6,8-dtbbenzox)}] ( 4 ), [{Mo^VIO₂}{en(3-tb,5-mb)₂(6-tb,8-mbbenzox)}] ( 5 ) and [{Mo^VIO₂}{en(3,5-dmb)₂(6,8-dmbenzox)}] ( 6 ), [{W^VIO₂}{en(3,5-dtbb)₂(6,8-dtbbenzox)}] ( 7 ), and [{W^VIO₂}{en(3-tb,5-mb)₂(6-tb,8-mbbenzox)}] ( 8 ). However, the benzoxazine ring ruptures in case of ligand IIc under these conditions and form [{W^VIO₂}{en(3,5-dmb)₃}] ( 10 ), similar to complexes 1–3 . Complex [{W^VIO₂}{en(3,5-dmb)₂(6,8-dmbenzox)}] ( 9 ), having structure similar to 4–8 , could only be obtained when the reaction was carried out in toluene. Not only 9 , even complexes 4–8 can be isolated in toluene. Rupturing of both benzoxazine rings has also been experienced when ligands 1,2-bis(6,8-disubstitutedbenzo[e][1,3]oxazin-3(4H)-yl)ethane [ I ( a–c )] react with [M^VIO₂(acac)₂] (M=Mo or W) in MeOH and give salan type complexes [(M^VIO₂)en(3,5-dtbb)₂] [M=Mo ( 11 ), M=W ( 14 )], [(M^VIO₂)en(3-tb,5-mb)₄] [M=Mo ( 12 ), M=W ( 15 )] and [(M^VIO₂)en(3,5-dmb)₄] [M=Mo ( 13 ), M=W ( 16 )]. Complexes 1–9 have been used as catalyst for the multicomponent Biginelli reaction for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) and oxidative bromination of phenol derivatives.     

Catalytic Potential of Pyrazolone Based Dioxidomolybdenum(VI) Complexes for Multicomponent Biginelli Reactions,Epoxidation of Olefins and Oxidative Bromination of Phenol Derivatives

Three different types of dioxidomolybdenum(VI) complexes of 4-acetyl-3-methyl-1-phenyl-5-pyrazolone (Hmp, I )), 3-methyl-1-phenyl-4-propionyl-5-pyrazolone (Hpp, II ), 4-butyryl-3-methyl-1-phenyl-5-pyrazolone (Hbutp, III ), and 4-isobutyryl-3-methyl-1-phenyl-5-pyrazolone (isobutp, IV ) have been isolated and characterized by various spectroscopic (FT-IR, UV/Vis, ¹H and ¹³C NMR) techniques, thermal analysis and single crystal X-ray analysis. These complexes adopt a distorted six-coordinate octahedral geometry where ligands act as bidentate, coordinating through the two O atoms. These complexes have been used as catalysts to explore a single pot multicomponent (benzaldehyde or its derivatives, urea/thiourea and ethyl acetoacetate/phenyl acetoacatate) Biginelli reaction producing biologically active 3,4-dihydropyrimidin-2-(1H)-one and 3,4-dihydropyrimidin-2-(1H)-thione based biomolecules under solvent-free conditions. Presence of H₂O₂ improves the yield of dihydropyrimidin-2-(1H)-one but it acts as poison for the later molecule. Epoxidation of internal and terminal alkenes mainly resulted in the formation of the corresponding epoxide. The catalytic oxidative bromination of thymol, a reaction facilitated by vanadium dependent haloperoxidases, resulted in the formation of three product namely 2-bromothymol, 4-bromothymol and 2,4-bromothymol. Other phenol derivatives have also been brominated effectively.     

Catalytic N-Alkylation of Amines with Aldehydes by a Molecular Mo Oxide Catalyst

Secondary and tertiary amine derivatives are very important in chemical and pharmaceutical industries. The N-alkylation of amines with aldehydes is a proper way to form secondary and tertiary amines. However, the traditional catalyst systems for this transformation bring a series of problems such as narrow substrate scope, challenges of difficult catalyst preparation and metal residues and toxicity. Herein an efficient way to perform N-alkylation of amines with aldehydes was described which used a molecular Mo oxide catalyst. In this pathway, various aldehyde and amine derivatives were successfully converted to the corresponding secondary and tertiary amines with high selectivity and efficiency. In addition, the catalyst was easy to prepare, and could be recycled six times without appreciable loss of conversion. Finally, the reaction mechanism was presented based on the observation of the possible intermediates and control experiments.     

Self-assembly of 2D-electrolytes into heterostructured nanofibers

2D materials can be functionalised with various ionisable functional groups of different formal charges, forming the so-called 2D electrolytes. In this study, 2D electrolytes based on functionalised graphene oxide (GO) with cationic groups (-NH₃⁺) and molybdenum disulfide (MoS₂) with anionic groups (-COO^-) were used to form heterostructures through a self-assembly process. Due to the presence of opposite charges, heterostructures were formed by the predominantly attractive forces between the 2D electrolytes in a fluidic aqueous environment. With the application of sonication, both 2D materials were able to overcome the energy barrier offered by their bending stiffness, continuously assembling and scrolling into heterostructured nanofibers. The nanofibers were the product of the conjugated 2D electrolytes, which led to their phase separation and precipitation into highly ordered and high aspect ratio 1D structures. As the reaction proceeds, long nanofiber bundles with branches were formed, resembling the structures formed by naturally occurring polyelectrolytes such as amino acids forming proteins. This method offers a facile approach for the continuous processing of heterostructured nanofibers with a low production cost under flow that can be widely applied in textiles, encapsulation technologies, and nanosensors.     

钨钼杂多化合物及其用途

简要介绍了钨、钼的性质和用途,主要综述了钨钼杂多化合物的合成方法、结构、性质,及其在催化、水质缓蚀剂、分析检测、生物医学、无机离子交换剂等方面的应用。     

微波消解-微波等离子体炬原子发射光谱法测定合金钢中的铜、锰、钼

用微波等离子体炬 (MPT)为激发光源 ,氩气为等离子体工作气体 ,用气动雾化进样 ,研究了微波消解 微波等离子体炬原子发射光谱法 (MPT AES)测定合金钢中铜、锰、钼的方法。考察了微波功率、载气流量、工作气流量、氧屏蔽气流量等实验参数对测定铜、锰、钼的影响。对微波消解合金钢样品的消解条件进行了考察 ,建立了最佳消解程序。测定铜、锰、钼的检出限分别为 3.3、3.7和 42ng mL ,RSD(n =6)分别为 1 7%、2 .4%、3.8% ,并且测得它们的线性范围分别为0 .0 2～ 5 0 μg mL、0 .0 4～ 5 0 μg mL和 0 .2 0～ 5 0 μg mL。     

砷剂诱导肿瘤细胞凋亡的研究进展

综述了国内外对砷剂诱导细胞凋亡的研究进展,以便更好地探求和开辟治疗恶性肿瘤的新途径。     

Effects of MoO3 Amounts on Sintering and Electrical Properties of Ce0.8Nd0.2O1.9

The high purity (Ce_0.8Nd_0.2O_1.9)_1-x(MoO₃)_x(x=0, 0.005, 0.010, 0.020; Ce_0.8Nd_0.2O_1.9=NDC) solid solutions were prepared by modified sol-gel method. The structures and electric conductivities were characterized by X-ray diffraction(XRD), field-emission scanning electron microscopy(FESEM) and electrochemical impedance spectroscopy( EIS). The XRD results show that the materials were pure phase with a cubic fluorite structure. Compared to the undoped-NDC samples, MoO3 doped-NDC showed higher sintered density(over 96%) at reduced sintering temperature. The electric conductivity(σ_t) of (Ce_0.8Nd_0.2O_1.9)_1-x(MoO₃)_x at 400 ℃ was 9.58×10^–4 S/cm when x=0.010, which was higher than that of undoped-NDC samples(σ_t=3.29×10^–4 S/cm). The obtained optimal amount of the MoO₃ was x=0.010 in this system.     

Synthesis,Structure, and Oxidation Catalysis of a Hybrid Compound of Bisubstituted Molybdovanadophosphate

A new compound, Na(HINA)₂(NH₄)₂[PMo₁₀V₂O₄₀] · 14H₂O ( 1 ) (INA = isonicotinic acid) was synthesized and characterized structurally by elemental analysis, IR spectroscopy, and TG. Bisubstituted molybdovanadophosphate anions have typical Keggin anion structure and are linked weakly by Na⁺ ions into an anionic chain along crystallographic b axis. Protonated INA cations form another supramolecular cationic chain also along crystallographic b axis. Two chains, water molecules, and ammonium ions form the 3D supramolecular architecture through hydrogen bonds. The compound has an excellent catalytic activity to starch oxidation. The detailed study gives optimum reaction condition.     

砒霜——亦敌亦友,千年情仇

It's believed that everyone is familiar with arsenic trioxide. It has been one of the most famous poisons since ancient time. Because of this, it is largely unfairly described. In this article, we combine research results with clear chemical knowledge and terms, in order to prove that arsenic trioxide can also be useful in human life and production.