Organic-phase enzyme electrode for phenolic determination based on a functionalized sol-gel composite

An amperometric biosensor for monitoring phenols in the organic phase was constructed by the silica sol-gel immobilization of tyrosinase on a glassy carbon electrode. The organic-inorganic hybrid materials with different sol-gel precursors and polymers were optimized, and the experimental conditions, such as the effect of the solvent, operational potential and enzyme loading were explored for the optimum analytical performance of the enzyme electrode. The biosensor can reach 95% of steady-state current in about 18 s, and the trend in the sensitivity of different phenols is as follows: catechol > phenol >p-cresol. In addition, the apparent Michaelis-Menten constants (K-m(app)) and the stability of the enzyme electrode were discussed. (C) 2000 Elsevier Science S.A. All rights reserved.

Confined crystallization behavior of PEO in silica networks

Poly(ethylene oxide) (PEO) and silica (SiO2) organic-inorganic hybrid materials have been synthesized by sol-gel approach. The crystallization behavior of PEO in silica networks has been investigated by differential scanning calorimeter (DSC) and scanning electron micrograph (SEM). The degree of PEO crystallinity in PEO/SiO2 hybrid networks reduces with the increase of SiO2. PEO is in amorphous state when the concentration of PEO is lower than 50 wt% in the hybrid materials. The melting points of PEO in the networks are lower than that of pure PEG, but the melting point of PEO in the networks almost has the same melting point. WAXD and SEM results show that the crystalline behavior of PEO in PEO/SiO2 hybrid system is sternly confined. (C) 1999 Elsevier Science Ltd. All rights reserved.

Electrophoretic migration behavior of DNA fragments in polymer solution

A newly developed polymer coil shrinking theory is described and compared with the existing entangled solution theory to explain electrophoretic migration behaviour of DNA in hydroxypropylmethylcellulose (HPMC) polymer solution in buffer containing 100 mM tris(hydroxymethyl)aminomethane 100 mM boric acid, 2 mm ethylenediaminetetraacetic acid at pH 8.3. The polymer coil shrinking theory gave a better model to explain the results obtained. The polymer coil shrinking concentration, C-s, was found to be 0.305% and the uniform entangled concentration, C+, 0.806%. The existence of three regions (the dilute, semidilute, and concentrated solution) at different polymer concentrations enables a better understanding of the system to guide the selection of the best conditions to separate DNA fragments. For separating large fragments (700/800 bp), dilute solutions (HPMC < 0.3%) should be used to achieve a short migration time (10 min). For small fragments (200/300 bp), concentrated solutions are preferred to obtain constant resolution and uniform separation. The best resolution is 0.6% HPMC due to a combined interaction of the polymer coils and the entangled structure. The possibility of DNA separation in semidilute solution is often neglected and the present results indicate that this region has a promising potential for analytical separation of DNA fragments.

A collision model for DNA separation by capillary electrophoresis in dilute polymer solution

A theoretical description. based on chemical kinetics and electrochemistry, is given of DNA separation in dilute polymer solution by capillary electrophoresis. A self-consistent model was developed leading to predictions of the DNA electrophoretic velocity as a function of the experimental conditions - polymer concentration, temperature, and electric field strength. The effect of selected experimental variables is discussed. The phenomena discussed are illustrated for the example of 100 bp DNA ladder separation in dilute HPMC solution by capillary electrophoresis. This model is the first single model that can fully explain the dependence of DNA electrophoretic velocity on electrophoretic conditions.

Assembly of side-functional monomers with inorganic nanometer particles

Monomers of methacrylate with various pi -conjugated pendants were designed and prepared in our laboratory, The monomer with suitable end-group was successfully assembled with nano-scale inorganic particles to form an orderly-aligned structure that showed special optical properties, both absorption and emission band were much red-shifted compared with the monomer, A new type of organic/inorganic hybrid materials was obtained by in situ polymerization of the assembly, The hybrid materials could also show special optical properties as the assembly, This might open a new route to tune the emission color.

Preparation and optical property of a novel hydrophobic anti-reflection coating for KDP crystal

A novel inorganic-organic hybrid hydrophobic anti-reflection silica film used for laser crystal was obtained by sol-gel process. The film consisted of silica sols mixed with a small amount of polymethyl methacrylate (PMMA) or polystyrene (PS). The optical transparency, hydrophobic property and surface morphology of the film were characterized by UV-VIS-NIR spectrophotometer; contact angle instrument and Scanning Electron Microscopy (SEM), respectively. The results showed that the anti-reflection coating had good hydrophobility and optical transparency from 400 nm to 1200 nm. The contact angle reached to 130-140 degrees. SEM images indicated the hydrophobic films modified with PMMA or PS had compact structure compared to the pure silica sol film. (C) 2008 Elsevier B.V. All rights reserved.

稀土(Er, Nd, Yb, Pr, Ho, Sm)有机/无机杂化材料的制备及发光性能研究

目前，国内外对于铕和铽等稀土配合物的可见区发光和应用都有大量研究，但对具有近红外发光（800-1700 nm）性能的稀土配合物的研究还处于起步阶段。由于稀土的近红外发光在光纤通讯、激光系统及诊断学等方面应用具有特殊的优点，越来越引起人们的兴趣和重视。 稀土近红外发光配合物的致命弱点是其光、热和化学稳定性较差，从而限制了其在很多领域的实际应用。而溶胶－凝胶材料和介孔材料具有良好的光、热和化学稳定性，能改善客体分子的结构环境和化学微环境，从而能有效提高客体分子的发光性能。因此，本论文将具有优良近红外发光性能的稀土配合物分别与上述两种基质复合，从实验和理论研究稀土近红外发光杂化材料的性能和应用价值，制备出具有良好稳定性的高效稀土近红外发光杂化材料，以期为光纤通讯、激光等领域提供潜在的候选材料。围绕这一宗旨，开展了如下工作： 通过原位技术分别得到了掺杂和嫁接[Ln(dbm)3phen]化合物（Ln = Er, Nd, Yb）的杂化凝胶材料，Ln-D-P gel和Xerogel-Ln。通过对其近红外发光性能的研究，表明材料中配体能很好的保护稀土离子，并将能量有效的传递给稀土离子。采用Judd-Ofelt理论对所得部分材料进行了光谱分析，基于实验数据和理论分析表明其具有潜在的光放大和激光应用价值。 选择了两种含全氟化烷基链的β-二酮配体Hhfth和Htfnb，通过功能化的phen-Si配体，将三元配合物[Ln(hfth)3phen] (Ln = Er, Nd, Yb, Sm)和[Pr(tfnb)3phen]成功共价嫁接到介孔MCM-41和SBA-15杂化材料中，得到的衍生材料Ln(hfth)3phen–MCM-41、Pr(tfnb)3phen–MCM-41和Ln(hfth)3phen–SBA-15、Pr(tfnb)3phen–SBA-15都保持了高度有序的介孔p6mm结构，并展现出稀土离子特征的近红外发射。所得稀土配合物功能化的材料的发射光谱能完全覆盖对光通讯极具应用价值的1300-1600nm区域。 通过对Er(dbm)3phen–M41(X, Y) (X = 1~14, Y = 3, 6, 12, 18, 24 h)材料系统的比较研究，选择了X = 12, Y = 6作为合成目标材料的优化参数，通过功能化的phen-Si配体将[Ln(dbm)3phen]配合物共价嫁接于有序介孔MCM-41和SBA-15中(Ln = Er, Nd, Yb)，所得两类材料Ln(dbm)3phenM41和Ln(dbm)3phenS15都保持了很好的介孔有序性，并具有良好的近红外发光性能。通过对Ln(dbm)3phenM41和Ln(dbm)3phenS15两类材料发光行为的比较，以及两类材料中稀土离子的含量及孔结构的分析，推出以SBA-15为载体得到的材料在相对发光强度和荧光寿命上，均比以MCM-41为载体的材料有所提高。 通过对8－羟基喹啉配体进行改性，合成了具有双功能的配体Q-Si，继而合成了共价嫁接8－羟基喹啉衍生物的介孔杂化材料Q–SBA-15，其形貌均一，并具有高度有序的介孔p6mm结构。通过配体交换反应，得到了嫁接稀土喹啉配合物的具有近红外发光性能的介孔杂化材料LnQ3–SBA-15 (Ln = Er, Nd, Yb)，其仍然保持高度有序的介孔结构，且外形呈现与母体材料Q–SBA-15相似的弯曲圆柱状。激发配体的吸收，LnQ3–SBA-15材料都分别展现出相应稀土离子特征的近红外发射，并详细分析和讨论了所得介孔杂化材料的近红外发光性能。

有机／无机杂化材料的自组装表征及应用

杂化的纳米尺寸的有机／无机化合物开辟了材料科学的新纪元。作为新型功能材料，杂化的有机／无机杂化材料由于在光学、电子、机械、防护涂层、催化、传感器、生物等方面有潜在的应用前景而在材料科学领域引起广泛关注。杂多酸（POMs）作为一种重要的无机化合物，有特异的纳米尺寸结构，优越的物理化学性质和广泛应用价值，因此多酸化合物功能材料的研究引起人们足够的重视。最近，人们把更多的注意力集中到杂化的有机／无机杂化材料范围内，如何更有序的组装杂多酸，因为它们有着更有趣的电、磁、氧化还原和光学性质。1．在4-氨基苯甲酸修饰的玻碳电极表面，我们用层层组装方法制备了六钒取代的理杂多酸（PW6V6）多层膜。表面等离子（SP）技术和循环伏安（CV）法对多层膜进行了表征。结果表明，多层膜生长均匀，平均厚度为2.8nm，并且研究了多层膜对亚硝酸根伽02一）和浪酸根（BrO3-）的催化还原活性。2．研究了通过静电吸附作用，P2W17Fe和QPvP-Os交替组装多层膜。循环伏安（CV），电化学交流阻抗谱（EIS）和紫外一可见光谱（UV－vis）研究结果表明了这种多层膜是均一稳定的。多层膜对H2O2，BrO3-和NO2-有很高的催化活性。特别是EIS成功地监测多层膜的形成过程。随着层数增长，电子传输阻抗Rc，线性增加，氧化还原电对Fe（CN）63/4的电子传输受到抑制，这进一步证实了多层膜的均一性。3，首次在4-氨基苯甲酸修饰的玻碳电极表面成功地构建了含杂多酸P2W15V3的多层膜。值得注意的是，该多层膜对BrO3-和NO2-的还原有显著的电催化活性，而且由于过渡金属钒在P2W15V3起催化作用而有很低的过电位。另外，多层膜中QPVP-O5聚合物的Os中心在抗坏血酸氧化时的催化活性仍然存在，而且通过最外层的调整，多巴胺和抗坏血酸能被分别检测，所以在多巴胺存在时它可用作检测抗坏血酸的电化学传感器。4．迄今为止，人们把更多的注意力集中在杂多酸多层膜的制备，电化学和电催化活性的研究，对杂多酸多层膜功能材料的研究却很少，我们首次够构造了发光的杂多酸多层膜，紫外可见光谱，循环伏安，电化学阻抗技术和荧光光谱证明多层膜生长均匀，室温下，多层膜的发光性能显示Eu3+的特征发射峰是5D0→7Fj（j=1，2，3，4）的跃迁。电化学阻抗谱被成功得应用于监测多层膜的沉积过程。我们发现随多层膜的逐步形成，半圆直径有规律地长大。而且，电荷迁移电阻Rc，随双层数线性增长。可以认为多层膜在基底电极上以非常均匀规律的方式沉积，Fe（CN）63/4氧化还原电对的氧化还原反应逐步被多层膜抑制。5．我们用层层组装方法成功构造了金纳米粒子多层膜，紫外可见光谱，循环伏安和原子力显微技术表征了多层膜的形成，金纳米粒子粒径大约14nm，表面粗糙度6.43nm。

Synthesis and spectroscopic study of mesoporous aluminum methylphosphonate foam templated by dibutyl methylphosphonate

New types of templates and novel interactive mechanisms between template and framework are very important for creating porous materials. In this work, by using neutral dibutyl methylphosphonate as a template, an inorganic-organic hybrid mesoporous material, aluminum methylphosphonate, was prepared. The as-synthesized material was studied by P-31 magnetic angle spinning nuclear magnetic resonance (MAS NMR), Al-27 MAS NMR, C-13 CP/MAS, FT-IR spectroscopy, thermogravimetry (TG), differential thermal analysis (DTA), and transmission electron microscopy. After thermal treatment at 673 K and 10 mmHg for 2 h, hybrid mesoporous foam was obtained. The transformation process was investigated by FT-IR. TG-DTA results indicate that the methyl group bonded to the framework keeps intact up to 792 K under air and 823 K under nitrogen. The characterization results from nitrogen gas adsorption-desorption measurements show that the BET surface area and the Barrett-Joyner-Halenda desorption cumulative pore volume of the foam are 90 m(2) g(-1) and 0.32 cm(3) g(-1) respectively. (C) 2003 Elsevier Inc. All rights reserved.

Ternary lanthanide (Er3+, Nd3+, Yb3+, Sm3+, Pr3+) complex-functionalized mesoporous SBA-15 materials that emit in the near-infrared range

The tertiary lanthanide complexes [Ln(hfth)(3)phen] (Ln=Er, Nd, Yb, Sm) and [Pr(tfnb)(3)phen] have been Successfully covalently attached in the ordered SBA-15 mesoporous materials via a functionalized 1,10-phenanthroline group 5-(N,N-bis-3-(triethoxysilyl)propyl)ureyl-1,10-phenanthroline (Phen-Si). The derivative materials [denoted as Ln(hfth)(3)phen-S15 and Pr(tfnb)(3)phen-S15; Ln=Er, Yb, Nd, Sm; hfth=4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)hexane-1,3-dionate; tfnb=4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedionate] were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and N-2 adsorption/desorption.

Near-infrared luminescence from sol-gel materials doped with holmium(III) and thulium(III) complexes

A series of ternary Ln(tta)(3)L complexes (Ln = Ho, Tm; Htta = 2-thenoyltrifluoroacetone; L = 1,10-phenanthroline, 2,2'-bipyridine, or triphenyl phosphate oxide) and their corresponding sol-gel hybrid materials formed via the in situ synthesis process (designated as Ln-T-L gel) were reported. The complexes and the gels were studied in detail, which suggest the complexes have been successfully synthesized in the corresponding gels.

DNA-Templated Gold Nanoparticles Formation

The interaction between HAuCl4 and DNA has enabled creation of DNA-templated gold nanoparticles without formation of large nanoparticles. It was found that spheral DNA-HAuCl4 hybrid of 8.7 nm in diameter, flower-like DNA-HAuCl4 hybrid, nanoparticles chains and nanoparticles network of DNA-HAuCl4 hybrid could be obtained by varying the reaction conditions, including DNA concentration and reaction temperature. The intermediate product was investigated by shortening the reaction time of DNA and HAuCl4, and the obtained nanoparticles preserved a small DNA segment, which indicated that the reaction between DNA and HAuCl4 had a process.

Weak epitaxy growth of organic semiconductor thin films

The fabrication of organic semiconductor thin films is extremely important in organic electronic devices. This tutorial review-which should particularly appeal to chemists and physicists interested in organic thin-film growth, organic electronic devices and organic semiconductor materials-summarizes the method of weak epitaxy growth (WEG) and its application in the fabrication of high quality organic semiconductor thin films.

Synthesis, Spectroscopic Properties, and Stabilities of Ternary Europium Complex in SBA-15 and Periodic Mesoporous Organosilica: A Comparative Study

Ternary europium complex Eu(tta)(3)phen was covalently bonded with the general mesoporous. material SBA-15 and SBA-15-type of periodic mesoporous organosilica (PMO) material via impregnation of Eu(tta)(3)center dot 2H(2)O into phen-S15 and phen-PMO, respectively, through a ligand exchange reaction. The parent materials of phen-S15 and phen-PMO were synthesized by co-condensation of tetraethylorthosilicate (TEOS) or 1,2-bis(triethoxysilyl)ethane (BTESE) and the functionalized chelate ligand 5-(N,N-bis(3-triethoxysilyl)propyl)ureyl-1,10-phenanthroline (phen-Si) in the presence of Pluronic P123 surfactant as template, which were confirmed by SEM, XRD, FTIR, Si-29 CP-MAS NMR, and N-2 adsorption measurements.