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.     

三氟丙基修饰的二氧化硅膜制备、氢气分离及其水热稳定性能

以三氟丙基三甲氧基硅烷(TFPTMS)和正硅酸乙酯(TEOS)作为前驱体,通过溶胶-凝胶法制备三氟丙基修饰的SiO2膜材料,研究了三氟丙基修饰对膜材料孔结构和疏水性的作用、疏水膜材料的氢气渗透和分离性能以及水热稳定性能。结果表明三氟丙基修饰后的膜材料仍保持良好的微孔结构,孔径狭窄分布在0.45~0.7 nm之间。修饰后膜材料疏水性明显提高,当nTFPTMS/nTEOS=0.6时,对水的接触角达到(102.7°±0.1°)。H2在修饰后膜材料的输运遵循微孔扩散机理,在300℃时,H2的单组份渗透率达到4.77×10-7mol.m-2.s-1.Pa-1,H2/CO2的理想分离系数以及双组份分离系数分别达到6.99和6.93,均高于其Knudsen扩散分离因子。在200℃水蒸气物质的量含量为5%的环境中陈化220 h后,H2的单组份渗透率仅在前3 h有轻微下降,然后基本保持不变,说明三氟丙基修饰的SiO2膜具有良好的水热稳定性。     

多孔石墨烯分离CH4/CO2的分子动力学模拟

采用分子动力学方法模拟CH₄/CO₂混合气体在多孔石墨烯分离膜中的分离过程, 分析了3 种纳米孔功能化修饰(N/H 修饰、全H修饰和N/―CH₃修饰)对分离过程的影响规律. 模拟结果表明气体分子会在石墨烯表面形成吸附层, CO₂分子的吸附强度高于CH₄分子. 纳米孔的功能化修饰不仅减小了纳米孔的可渗透面积, 还通过影响纳米孔边缘原子的电荷分布提高了气体分子的吸附强度, 进而影响了混合气体分子在多孔石墨烯分离膜中的渗透性和选择性. CO₂分子在多孔石墨烯中的渗透率能达到10⁶ GPU (1 GPU=3.35×10^-10 mol·s^-1·m^-2·Pa^-1), 远远高于传统的聚合物分离膜. 研究表明多孔石墨烯分离膜在天然气处理、CO₂捕获等工业气体分离过程中具有广泛的应用前景.     

互穿结构及混合配体对金属-有机骨架材料分离性能的影响

在以前的工作中, 我们利用蒙特卡洛和分子动力学模拟计算了具有互穿性结构及混合配体的金属-有机骨架材料(metal-organic frameworks, MOFs)分离CH₄/H₂的吸附选择性及扩散选择性. 研究了材料的互穿结构及混合配体对材料用于分离CH₄/H₂性能的影响. 在本工作中, 我们将以前的工作进行了扩展, 详细研究了材料的互穿结构及混合配体对材料用于分离CO₂/CH₄, CO₂/N₂和CO₂/H₂等含有CO₂的气体混合物性能的影响. 此外, 为了进一步阐明材料的结构对于其分离性能的影响, 我们亦研究了材料用于分离CH₄/H₂及CH₄/N₂. 从我们的结果可以看出, 相比无互穿结构的MOFs材料, 具有互穿结构的MOFs材料对所研究的所有混合气体的渗透选择性明显提高. 这是因为具有互穿结构的MOFs材料对混合气体的吸附选择性明显高于无互穿结构的MOFs材料. 结果表明, 如果将材料作为膜用于气体混合物分离, 使材料产生互穿结构是提高材料分离性能的一个很好的策略.     

三氟丙基修饰的二氧化硅膜制备、氢气分离及其水热稳定性能

以三氟丙基三甲氧基硅烷(TFPTMS)和正硅酸乙酯(TEOS)作为前驱体,通过溶胶-凝胶法制备三氟丙基修饰的SiO₂膜材料,研究了三氟丙基修饰对膜材料孔结构和疏水性的作用、疏水膜材料的氢气渗透和分离性能以及水热稳定性能。结果表明三氟丙基修饰后的膜材料仍保持良好的微孔结构,孔径狭窄分布在0.45~0.7 nm之间。修饰后膜材料疏水性明显提高,当n_TFPTMS/n_TEOS=0.6时,对水的接触角达到(102.7°±0.1°)。H₂在修饰后膜材料的输运遵循微孔扩散机理,在300 ℃时,H₂的单组份渗透率达到4.77×10^-7 mol·m^-2·s^-1·Pa^-1,H₂/CO₂的理想分离系数以及双组份分离系数分别达到6.99和6.93,均高于其Knudsen扩散分离因子。在200 ℃水蒸气物质的量含量为5%的环境中陈化220 h后,H₂的单组份渗透率仅在前3 h有轻微下降,然后基本保持不变,说明三氟丙基修饰的SiO₂膜具有良好的水热稳定性。     

表面修饰的有机-无机杂化微孔SiO2膜的制备及氢气分离性能

采用苯基三乙氧基硅烷(PTES)和1,2-双(三乙氧基硅基)乙烷(BTESE)为前驱体, 通过溶胶-凝胶法制备了苯基修饰的有机-无机杂化SiO2 膜材料. 通过N2吸附、视频光学接触角测量、热重分析和红外光谱对膜材料的孔结构和疏水性能进行了表征, 并深入研究了膜材料的氢气渗透和分离性能. 结果表明, 修饰后的膜材料具有微孔结构, 孔径集中分布在0.4~0.6 nm. 在温度为40 ℃, 湿度为70%~80%的水热环境下陈化30 d后, 膜材料仍保持微孔结构. 苯基修饰后膜材料具有疏水性, 当n(PTES)/n(BTESE)=0.6时, 膜材料对水的接触角达到(125±0.4)°. 氢气在膜材料中的输运遵循活化扩散机理, 300 ℃时, 膜材料的H2渗透率达到8.71×10-7mol·m-2·Pa-1·s-1, H2/CO2的理想分离系数达到5.53.     

SIFSIX-3-Ni膜的制备及氢气分离性质

利用(NH₄)₂SiF₆修饰大孔玻璃基底后, 在溶剂热条件下制备了SIFSIX-3-Ni膜, 并研究了温度和浓度对制备SIFSIX-3-Ni膜的影响. 能谱分析(XPS)结果表明大孔玻璃表面引入了氟元素. SIFSIX-3-Ni膜的粉末X射线衍射(PXRD)峰位置和模拟结果一致, 表明成功制备出SIFSIX-3-Ni膜. 从扫描电子显微镜(SEM)照片中观察到膜连续均匀, 厚度约为20 μm. 热重分析(TGA)结果表明, 活化前的膜没有客体分子. 单组分测试结果表明, 膜的H₂, CO₂和N₂渗透量分别为6.83×10 ^-6, 7.42×10 ^-7和8.89×10 ^-7 mol·m ^-2·s ^-1·Pa ^-1, H₂/CO₂和H₂/N₂的理想分离比分别为9.20和7.68. 在连续测试5 h后, H₂, CO₂和N₂渗透量基本保持不变, 表明SIFSIX-3-Ni膜具有很好的稳定性.     

多孔材料表面修饰聚酰亚胺非对称混合基质膜对CO2/N2和CO2/CH4的气体分离

兼具高通量和高选择性的气体分离膜是研究膜分离材料的目标.采用相转化法制备了聚酰亚胺非对称膜,并将其作为基底膜材料,分别在其表面修饰掺有金属有机框架材料Cu₃(BTC)₂ (1, 3, 5-均苯三甲酸合铜),沸石咪唑酯骨架材料ZIF-8以及镁铝水滑石MgAl-LDHs的聚酰胺酸溶液,经热亚胺化后制成非对称混合基质膜.研究了该系列非对称混合基质膜的结构特性和对CO₂、CH₄和N₂气体分离性能;考察了ZIF-8的掺杂量对非对称混合基质膜透气性能的影响.结果表明非对称聚酰亚胺膜的表面修饰可有效地改变膜的表面性质,掺杂ZIF-8的非对称混合基质膜气体的透气性能和选择性都增加,且掺杂量为5% (w)时CO₂/N₂和CO₂/CH₄的理想选择性分别高达24和83,为合成高效的CO₂分离膜提供了借鉴.     

具有不对称孔道结构的小介孔二氧化硅粒子的合成及其高分子杂化膜的构建

利用手性阴离子酸表面活性剂, 采用软模板法制备了具有不对称孔道结构的小介孔二氧化硅(SiO₂)粒子. 将小介孔SiO₂粒子引入聚偏四氟乙烯(PVDF)和聚酰亚胺(PI)中构建了两种有机/无机杂化膜. 利用傅里叶变换红外光谱(FTIR)、 透射电子显微镜(TEM)、 扫描电子显微镜(SEM)和比表面积分析等表征了小介孔SiO₂粒子和有机/无机杂化膜的微结构, 并通过超滤实验和气体渗透实验分别考察两种杂化膜的性能. 研究结果表明, 表面含有大量亲水基团的小介孔SiO₂粒子具有规则有序排列的孔道结构, 该孔道结构呈现螺旋扭曲和不对称性. 构建的两种有机/无机杂化膜的极性显著提升, 进而有效增强了PVDF杂化膜的膜通量和抗污染性能及PI杂化膜对CO₂气体的分离性能, 克服了高分子膜的博弈效应(Trade-off效应). 另外, SiO₂的小介孔孔道还可以在PI杂化膜中引入优先通过CO₂分子的限域传质通道, 加速了CO₂气体在杂化膜中扩散. 但过多小介孔SiO₂粒子的加入导致其在高分子基质中团聚, 削弱杂化膜的极性和亲水性, 从而降低了两种杂化膜的分离性能.     

硅烷表面修饰引发的ZnO微米棒膜的超疏水性

采用简单的低温水热法制备出ZnO微米棒薄膜,其经辛基三甲氧基硅烷和十二氟庚基丙基三甲氧基硅烷修饰后显示出超疏水性,静态接触角分别为(150±1.3)°和(155±1.5)°,滚动角依次为5°和3°。 ZnO微米棒的微结构和低表面能材料辛基三甲氧基硅烷、十二氟庚基丙基三甲氧基硅烷的表面修饰是其显示超疏水性的原因,用Cassie理论对膜的润湿性进行了分析。     

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.     

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.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.