新型杂多酸[Bu4N][Ni(pph3)2]PW11O39硅溶胶修饰电极电化学性质及电催化研究

采用溶胶-凝胶技术制备了新多金属氧酸盐[Bu4N][Ni(pph3)2]PW11O39(Bu为四丁基,pph为苯基磷)有机-无机杂化材料修饰电极,该修饰电极不仅保持了本体溶液的电化学和电催化性质,而且还具有很好的稳定性与灵敏度.研究表明,优选条件下修饰电极在pH=4.5的缓冲溶液中,其催化电流与NO2-浓度在6.0×10-6~1×10-3mol/L范围内呈良好的线性关系,对不同基质环境水样的加标回收率为97%~102%,方法的检出限为1.0×10-7mol/L,对1.0×10-4mol/L NO2-平行测定10次的相对标准偏差(RSD)为1.96%.     

二氧化硅-聚苯胺(SiO2-PANI)杂化透明导电薄膜的制备和表征

本文采用溶胶-凝胶法,以3-巯丙基三甲氧基硅烷(MPTMS)和聚苯胺为主要原料,制备得到有机-无机杂化透明导电薄膜.着重研究制备过程中醋酸、间甲酚和聚苯胺含量对薄膜结构、导电性和可见光透过率的影响.通过红外光谱可知,采用溶胶-凝胶法可制得结构稳定的杂化导电材料.醋酸作为水解缩聚反应的反应剂和催化剂,当其与3-巯丙基三甲氧基硅烷的物质的量比为0.4时.MPIMS的水解缩聚速率和聚苯胺掺杂入无机前驱体的掺杂速率达到平衡.此外,透明杂化导电薄膜的方块电阻随间甲酚和聚苯胺含量的增加而降低,当间甲酚和3-巯丙基三甲氧基硅烷的物质的量比为5,聚苯胺和二氧化硅的质量比为3/7时,薄膜的方块电阻为3.23 kΩ/□,可见光透过率为80%.     

聚乙烯醇缩丁醛/氧化铝杂化高分子材料的研究

由异丙醇铝与乙酰丙酮反应制备铝 乙酰丙酮螯合物 ,由此通过控制水解制备Al2 O3 溶胶 .该溶胶与聚乙烯醇缩丁醛分子上残存的羟基发生交联生成有机 无机溶胶 (OIS) .OIS经成型和干燥后即可方便地形成耐溶剂性的有机 无机杂化高分子材料 ,如透明薄膜和高弹纤维 .将OIS涂覆在碳纤维束丝上 ,热处理无机化后 ,可得到非常均匀致密的无定形氧化铝 -碳涂层 .该涂层可明显提高碳纤维的耐高温氧化性和表面特性     

荧光磁性双功能Fe_3O_4/Alendronate@CdSe/CdS纳米复合物的制备与表征

采用化学共沉淀法制备了磁性Fe3O4纳米颗粒,并用四甲基氢氧化铵(TMAOH)、阿伦磷酸钠、丙烯酸丁酯和无水乙二胺对Fe3O4纳米颗粒表面进行修饰,制备出3代表面胺基化的Fe3O4树状分子.采用油相合成的方法制备CdSe/CdS量子点,再用巯基乙酸进行修饰,使其具有良好的水溶性和较好的稳定性.将制备的Fe3O4树状分子与修饰后的量子点进行连接,制备出双功能树状Fe3O4/Alendronate@CdSe/CdS微球.通过这种方法得到的材料的荧光性能明显增强,但材料的荧光性能并不随代数成线性变化的.     

基于溶胶-凝壳聚糖/SiO2杂化材料的安培型葡萄糖生物传感器

近年来 ,基于溶胶 -凝胶技术的有机 /无机杂化复合材料由于具有有机物的柔性和易修饰性 ,以及无机物的刚性和稳定性等 ,因此有利于保持生物分子的活性和生物传感器的研制 [1] .壳聚糖 ( CS)具有易成膜性和生物相容性 ,其在生物传感器中的研究已受到重视 [2 ] .本文通过原位溶胶 -凝胶 ( Sol- gel)技术 ,用 CS和甲基三甲氧基硅烷 ( MTOS)制备了 CS/Si O2 有机 /无机杂化材料 ,并将其用于对葡萄糖氧化酶 ( GOD)的固定 ,研制出葡萄糖生物传感器 .采用人工过氧化物酶普鲁士蓝 ( PB) [3]作为电子传递的媒介体 ,并外加一层 Nafion膜以增强…     

RAFT聚合制备PBMA/AA-SiO2杂化纳米材料

以三硫代二[4-(甲氧羰基)苄基]碳酸酯为链转移剂(CTA),甲基丙烯酸丁酯(BMA)为单体,通过可逆加成-断裂链转移自由基聚合(RAFT)法修饰丙烯酸(AA)功能化的纳米二氧化硅(SiO2),制备了PBMA/AA-SiO2有机/无机杂化纳米材料。并通过FT-IR、GPC、TGA、TEM表征和分析了杂化材料的结构、分子量、SiO2纳米粒子在基体中的分散性以及杂化材料的热稳定性。结果表明,PBMA/AA-SiO2杂化微球粒径约为22 nm,分布均匀;TGA分析表明此杂化材料的热稳定性良好,PBMA接枝率为19%。     

二氧化硅-聚苯胺(SiO2-PANI)杂化透明导电薄膜的制备和表征

本文采用溶胶-凝胶法,以3-巯丙基三甲氧基硅烷(MPTMS)和聚苯胺为主要原料,制备得到有机-无机杂化透明导电薄膜。着重研究制备过程中醋酸、间甲酚和聚苯胺含量对薄膜结构、导电性和可见光透过率的影响。通过红外光谱可知,采用溶胶-凝胶法可制得结构稳定的杂化导电材料。醋酸作为水解缩聚反应的反应剂和催化剂,当其与3-巯丙基三甲氧基硅烷的物质的量比为0.4时,MPTMS的水解缩聚速率和聚苯胺掺杂入无机前驱体的掺杂速率达到平衡。此外,透明杂化导电薄膜的方块电阻随间甲酚和聚苯胺含量的增加而降低,当间甲酚和3-巯丙基三甲氧基硅烷的物质的量比为5,聚苯胺和二氧化硅的质量比为3/7时,薄膜的方块电阻为3.23 kΩ/□,可见光透过率为80%。     

聚(2-甲氧基-5-丁氧基)对苯乙炔/Eu2O3纳米复合材料的合成及其光学效应

采用原位脱氯化氢缩合聚合法制备了聚(2-甲氧基-5-丁氧基)对苯乙炔/氧化铕(PMOBOPV/Eu2O3)纳米复合材料. 傅里叶变换红外(FT-IR)光谱证实了在Eu2O3表面的包覆层为PMOBOPV. 高分辨透射电子显微镜(HRTEM)观察发现, PMOBOPV/Eu2O3纳米复合材料具有核-壳结构, 直径为75-145 nm, 其中PMOBOPV包覆层厚度约为25 nm. 紫外-可见(UV-Vis)吸收光谱表明, 随着Eu2O3含量增加, PMOBOPV/Eu2O3的最大吸收峰发生红移且强度提高. 荧光光谱研究表明, 随着Eu2O3含量增加, PMOBOPV/Eu2O3的最大发射波长发生蓝移且强度提高, Eu2O3与PMOBOPV之间形成了光致电子转移体系, 使π电子离域程度增加, 并且导致荧光量子效率提高. 根据光学禁带宽度(Eg)与入射光子能量(hυ)的关系, 拟合了PMOBOPV/Eu2O3薄膜的光学禁带宽度, 发现随着Eu2O3含量增加, Eg逐步减小. 采用简并四波混频方法测试它们的三阶非线性极化率(χ(3)), 发现随着Eu2O3含量增加, PMOBOPV/Eu2O3纳米复合体的非线性光学响应逐渐增强, 这说明PMOBOPV与Eu2O3之间形成了分子间光致电子转移体系, 产生了复杂的分子间离域π电子非线性运动.     

溶胶-凝胶法制备丙烯酸树脂/TiO2有机-无机杂化材料及其结构表征

通过预水解的二氧化钛(TiO2 )溶胶与丙烯酸树脂共混或原位聚合的方法制备了均匀透明的丙烯酸树脂 TiO2 有机 无机杂化材料.考察了TiO2 溶胶制备方法、聚合物中—COOH官能团含量和杂化材料制备方法对杂化材料结构的影响.索氏抽提实验表明聚合物中的羧酸官能团和无机TiO2 相间发生了交联反应,且随着—COOH官能团含量的增加,交联程度增大.小角X射线散射(SAXS)结果发现,杂化材料中TiO2 为疏松的三维网状结构,且在纳米尺度范围内,但这种三维网状结构随着TiO2 溶胶制备中水或酸的用量增加,其致密度增加,尺寸增大.同原位聚合法相比,共混法可制备出更均匀的杂化体系,且TiO2 为单分散.     

十七氟癸基修饰的有机-无机杂化二氧化硅膜材料的制备及气体分离性能

以十七氟癸基三乙氧基硅烷(PFDTES)和1,2-双(三乙氧基硅基)乙烷(BTESE)为前驱体, 通过溶胶-凝胶法制备了十七氟癸基修饰的SiO₂溶胶, 采用浸渍提拉法在γ-Al₂O₃/α-Al₂O₃多孔陶瓷支撑体上涂膜, 然后在N₂气氛保护下烧结成完整无缺陷的有机-无机杂化SiO₂膜. 利用扫描电子显微镜对膜材料的形貌进行观察, 通过动态光散射技术对溶胶粒径及分布进行测试, 利用视频光学接触角测量仪、 红外光谱仪和热分析仪表征了十七氟癸基修饰对有机-无机杂化SiO₂膜疏水性的影响. 结果表明, 十七氟癸基已经成功修饰到SiO₂膜材料中, 且随着PFDTES加入量的增大, 溶胶粒径和膜材料对水的接触角不断增大. 当n(PFDTES): n(BTESE)=0.25: 1时, 溶胶粒径分布较窄, 平均粒径为3.69 nm, 膜材料对水的接触角为(112.0±0.4)º. 在修饰后的有机-无机杂化SiO₂膜中H₂的输运遵循微孔扩散机理, 在300℃时, H₂的渗透率达到5.99×10^-7 mol·m^-2·Pa^-1·s^-1, H₂/CO和H₂/CO₂的理想分离系数分别达到9.54和5.20, 均高于Knudsen扩散的理想分离因子, 表明膜材料具有良好的分子筛分效应.     

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.