Keggin型铜取代磷钨杂多阴离子可见光催化降解罗丹明B

以Keggin型铜取代杂多阴离子PW11O39Cu(Ⅱ)(H2O)5-[PW11Cu]为可见光催化剂,有机染料罗丹明B(RhB)为模型污染物,研究了在可见光照射下PW11Cu对RhB的可见光催化降解作用,提出了PW11Cu可见光催化作用的反应机理,同时考察了RhB初始浓度、PW11Cu初始浓度和溶液pH值对RhB光催化降解速率的影响。 实验结果表明,含有15.6 μmol/L PW11Cu+10 μmol/L RhB的水溶液在可见光照射下反应80 min,RhB的降解率达100%,总有机碳去除率约33%。 RhB的可见光催化降解服从准一级动力学方程,在RhB初始浓度为20、30和40 μmol/L的情况下,其表观一级速率常数分别为3.1×10-2、2.0×10-2和1.5×10-2 min-1。     

Keggin型铬取代杂多阴离子/D301R可见光催化性能

将Keggin型铬取代磷钨杂多阴离子PW11O39Cr(Ⅲ)(H2O)4-(PW11Cr)负载于弱碱性阴离子交换树脂D301R表面,制备了固体光催化剂PW11Cr/D301R,并以模型污染物罗丹明B(RhB)的降解为探针评估了该催化剂的可见光催化活性,讨论了光催化反应机理,同时考察了催化剂剂量、溶液pH值和溶液中常见离子对RhB可见光催化降解反应的影响以及催化剂的稳定性。 实验结果表明,当PW11Cr/D301R的剂量为100 mg时,10 μmol/L RhB水溶液暴露在200 W金卤灯下进行照射,RhB完全降解所需的时间仅为30 min,比PW11Cr均相体系缩短了3倍;反应180 min总有机碳(TOC)去除率约为84%。 催化剂剂量、溶液pH值和溶液中存在的Cl-、SO2-4和PO3-4对RhB光催化降解反应的速率均有一定影响。 催化剂循环实验显示经循环使用7次后催化剂的活性几乎没有损失。     

Keggin型铬取代杂多阴离子/阴离子交换树脂的可见光催化性能

将Keggin型铬取代磷钨杂多阴离子PW11O39Cr(Ⅲ)(H2O)4-(PW11Cr)负载于弱碱性阴离子交换树脂D301R表面,制备了固体光催化剂PW11Cr/D301R,并以模型污染物罗丹明B(RhB)的降解为探针评估了该催化剂的可见光催化活性,讨论了光催化反应机理,同时考察了催化剂剂量、溶液pH值和溶液中常见离子对RhB可见光催化降解反应的影响以及催化剂的稳定性。实验结果表明,当PW11Cr/D301R的剂量为100 mg时,10μmol/L RhB水溶液暴露在200 W金卤灯下进行照射,RhB完全降解所需的时间仅为30 min,比PW11Cr均相体系缩短了3倍;反应180 min总有机碳(TOC)去除率约为84%。催化剂剂量、溶液pH值和溶液中存在的Cl-、SO2-4和PO3-4对RhB光催化降解反应的速率均有一定影响。催化剂循环实验显示经循环使用7次后催化剂的活性几乎没有损失。     

可见光照射下SiW12O4-40/Resin光催化剂活化H2O2降解染料的研究

将杂多酸(SiW12O4-40)负载到阴离子交换树脂上,得到SiW12O4-40/Resin(SWR)固相光催化剂,在可见光的照射下,可以有效地活化H2O2降解染料.以罗丹明B(Rhodamine B,RhB)为模型化合物,研究了不同条件下RhB的降解动力学,以及降解过程中其UV-vis光谱及体系的总有机碳(Total Organic Carbon,TOC)变化情况,结果表明RhB的共轭芳环结构被破坏,矿化率为24.2%.其它染料如孔雀绿(Malachite Green,MG)和吖啶橙(Acridine Orange,AO)等也可以被降解和矿化.催化剂的循环实验表明SWR固相光催化剂易于分离,并且具有良好的稳定性,可以重复利用.     

可见光/Fenton光催化降解有机染料

采用Fenton试剂(Fe³⁺/H₂O₂)在可见光条件下(λ＞450nm)光催化降解目标染料化合物罗丹明B(RhodamineB,RhB).在pH＜3.0体系中用可见光照射,能使RhB染料在光敏化作用下有效降解,反应160min后矿化率达到71.8%.采用ESR和溴甲酚绿(Bromocresolgreen,BCG)法跟踪测定活性氧化物种,通过对RhB降解过程的紫外-可见光谱、红外光谱分析及总有机碳量(TOC)跟踪测定,结果表明,Fe³⁺/H₂O₂/RhB体系在可见光照射下主要的活性氧化物种为羟基自由基,能有效地降解RhB.     

Hg掺杂CdS的制备及可见光降解有毒有机污染物

采用镉硫共沉淀方法制备了Hg掺杂CdS(Hg_xCd_1-xS)光催化剂,运用X射线衍射法(XRD)、X射线光电子能谱(XPS)、透射电镜(TEM)和紫外-可见吸收光谱对所制备的催化剂进行了表征;利用可见光催化降解罗丹明B(Rhodi-amine B,RhB)和2,4-二氯苯酚(2,4-dichlorophenol,2,4-DCP)为探针反应,对Hg_xCd_1-xS可见光催化活性进行了研究,通过跟踪RhB降解过程中吸收光谱的变化和总有机碳(TOC),评价了Hg_xCd_1-xS对有机物的氧化降解及深度矿化能力.结果表明:Hg_xCd_1-xS催化剂为立方晶型,Hg的最佳掺杂量为5%,其禁带宽度约为2.15 eV,对RhB和2,4-DCP均有较好的降解效果,实验条件下30 min RhB褪色率为100%,RhB的30 h矿化率为45.5%,2,4-DCP的16 h降解率达55%.Hg_xCd_1-xS可见光光催化降解RhB具有较高的稳定性,Hg的掺杂能有效降低CdS光腐蚀问题.通过ESR跟踪测定光催化反应过程中产生的自由基,表明降解过程涉及·OH机理.     

铬取代杂多阴离子PW11O39Cr（Ⅲ）（H2O）4-可见光催化降解罗丹明B

为了利用太阳光能去除水体有机染料污染物,以Keggin型铬取代杂多阴离子PW11O39Cr(III)(H2O)4-(PW11Cr)为光催化剂, 详细研究在可见光照射下PW11Cr对水体有机染料污染物罗丹明B(RhB)的光催化降解作用, 考察RhB和PW11Cr初始浓度以及溶液pH对RhB可见光催化降解速率的影响, 并通过可见吸收光谱和荧光发射光谱研究水溶液中PW11Cr和RhB的相互作用, 提出PW11Cr光催化作用的机理. 实验结果表明,含有50 μTTmol·L-1 PW11Cr和10 μTTmol·L-1 RhB的水溶液在200 W可见光下照射120 min, RhB的降解率达到100%,总有机碳去除率约32%. 在PW11Cr浓度较大和pH<3.5的酸性条件下, PW11Cr与RhB之间易发生络合, 导致RhB光降解速率变慢,而PW11Cr浓度为50 μTTmol·L-1和溶液接近中性条件下, RhB的光降解速率较快.     

非水溶性席夫碱铁疏水异相光催化降解有毒有机污染物

通过化学方法合成了疏水性金属有机复合物双（水杨醛）邻苯二胺席夫碱铁（Fe-Bis-Schiff-base- salicylaldehyde-o-Phenylenediamine,Fe-SPA）。在水溶性介质体系中,以Fe-SPA疏水特性作为异相光催化剂降解有毒有机污染物,在pH 7.2介质,可见光（λ>420nm）照射下,通过Fe-SPA活化H2O2降解有毒有机污染物罗丹明B（Rhodamine B,RhB）、亚甲基蓝（Methylene Blue trihydrate,MB）和2,4-二氯苯酚（2,4-Dichlorophenol,2,4-DCP）,研究了Fe-SPA的光催化特性。在实验条件下,反应150min RhB褪色完全,反应300min MB 褪色完全,反应10h DCP降解率达到65%。采用ESR（电子顺磁共振）跟踪测定活性氧化物种,检测到催化体系中产生了高氧化活性羟基自由基。通过RhB体系降解过程中的紫外-可见光谱和红外光谱分析,表明目标底物有效降解且最终转化为胺类和羧酸类小分子。在水溶性介质体系中,Fe-SPA以疏水特性作为异相光催化剂具有良好的稳定性,循环使用5次,光催化活性基本稳定。     

席夫碱铁-TiO2复合物光催化降解有毒有机污染物

运用化学合成方法制备了双(5-磺酸钠水杨醛)邻苯二胺席夫碱[N,N -Bis-schiff-base-5-sulfonate-salicylalidene- o-phenylenediamine sodium, SSPA]铁(III)配合物(FeSSPA), 采用无机钛盐醇解法制备了席夫碱铁-TiO₂复合物催化剂(FeSSPA-TiO₂). 通过紫外-可见反射光谱(UV-Vis DRS)、透射电镜(TEM)对制备催化剂进行了表征. 利用FeSSPA-TiO₂可见光(λ＞420 nm)激发活化分子氧降解有机染料罗丹明B (Rhodamine B, RhB)、无色小分子2,4-二氯苯酚(2,4-Dichlorophenol, 2,4-DCP)及水杨酸(Salicylic acid, SA), 研究了FeSSPA-TiO₂的光催化性能. 结果表明, FeSSPA-TiO₂光催化剂在pH 6.7, 可见光照射条件下, 80 min RhB褪色率达到100%, 20 h小分子2,4-DCP, SA的降解率分别达到67%, 100%. 在实验条件下, 33 h对RhB矿化率达到70.5%. 通过反应过程中氧化物种的测定, 发现降解过程主要涉及超氧自由基( )的氧化机理.     

Visible Photocatalytic Degradation of Rhodamine B Using Keggintype Cr（Ⅲ）-Substituted Heteropolyanion PWllO39Cr（Ⅲ）（H2O）4-

为了利用太阳光能去除水体有机染料污染物,以Keggin型铬取代杂多阴离子PW11O39Cr（III）（H2O）4-（PW11Cr）为光催化剂, 详细研究在可见光照射下PW11Cr对水体有机染料污染物罗丹明B（RhB）的光催化降解作用, 考察RhB和PW11Cr初始浓度以及溶液pH对RhB可见光催化降解速率的影响, 并通过可见吸收光谱和荧光发射光谱研究水溶液中PW11Cr和RhB的相互作用, 提出PW11Cr光催化作用的机理. 实验结果表明,含有50 μTTmol·L-1 PW11Cr和10 μTTmol·L-1 RhB的水溶液在200 W可见光下照射120 min, RhB的降解率达到100%,总有机碳去除率约32%. 在PW11Cr浓度较大和pH〈3.5的酸性条件下, PW11Cr与RhB之间易发生络合, 导致RhB光降解速率变慢,而PW11Cr浓度为50 μTTmol·L-1和溶液接近中性条件下, RhB的光降解速率较快.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.