Synthesis of carboranyl derivatives of deuteroporphyrin IX

Carboranylporphyrins, which can be used in boron neutron-choture therapy of cancer, were prepared from natural deuteroporphyrin IX, 3-amino-o-carborate, and 9-hydroxymethyl-m-carborane. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2337–2339 December, 1999.     

Effect of albumin on the aggregation of deuteroporphyrin in aqueous organic medium

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物理有机化学前沿领域两个重要方面--有机分子簇集和自由基化学的研究

有机分子簇集和自卷是研究疏水亲脂作用（HLI）最基本和最简单的模型，它直接影响受体分子的反应性和生物功能，用物理有机化学的概念和方法研究簇集和自卷是了解HLI最好的途径之一。自由基化学研究中，取代三氟苯乙烯是迄今为止唯一可真正拆分取代基极性效应和自旋离域效应的体系。σJJ是最可靠和种类最多的反映取代基自旋离域能力的参数，首次提出一般情况下，可用双参数方程系数|ρ^＋/ρJJ|比值作为取代基极性效应和自旋离域效应相对权重的判别尺度，将自由基反应及波谱参数的相关分析分为四种类型，成功解决了长期困扰自由基化学界如何评估这两种效应的重大问题。     

The effect of hydrophobic-lipophilic interactions on chemical reactivity. 10. The competition between the aggregation of long-chain esters and the formation of inclusion complexes of these esters with amylose

The hydrolytic pseudo-first-order rate constants (k _ad) ofp-nitrophenyl esters of dodecanoic acid (C12) and hexadecanoic acid (C16) at different initial substrate concentrations ([S] _i ) in the six aquiorgano binary mixtures of different compositions (ϕ) were measured. These rate constants (k _ad) were compared with the corresponding rate constants obtained in the absence of sodium carboxymethylamylose (Na-CMA) (k _un) in order to study the competition between the formation of inclusion complexes of these esters with Na-CMA and the aggregation of these long-chain substrates. Values of ΔCAgC andk _ad/k _un were compiled and their significance discussed on the basis of a postulated two-path mechanism. Our results suggest that in addition to path A which involves encapsulation by Na-CMA of the monomeric C12 or C16 only, there is a second path (path B). Path B describes a process in which Na-CMA breaks up aggregates of all sizes into smaller ones as well as monomeric species which can be wrapped-up by Na-CMA simultaneously or subsequently.     

Enthalpies of solution of tetramethyl-ammonium chloride in aqueous-organic binary solvent systems

Enthalpies of solution of tetramethylammonium chloride in H₂O+acetone, H₂O+DMSO, and H₂O+2,2,2-trifluoroethanol (TFE) are reported. The enthalpies of solution for the frist two solvent systems are positive for all compositions investigated, whereas for the H₂O+TFE systemsH_s becomes large and negative as the mole fraction of TFE is increased past 0.2. The enthalpy-of-solution data are rationalized on the basis of solvent structural effects and solvation.     

Flow injection determination of diesters as ferric hydroxamate complexes

Diesters such as succinylcholine chloride (SCC) and dioctylsulfosuccinate (DOSS) can be converted to hydroxamic acids which are found to react with Fe³⁺ in methanol to form a purple chelate complex having an useful absorption band at 520 nm with a molar absorptivity of about 171 L/mole*cm, and a detection limit of 1.5 × 10^–4 M. To adapt this method for flow injection, a methanol-water solvent and acidification of the sample were required to reduce the large blank peak. The reproducibility of the flow injection method was a factor of two better than standard spectrophotometry but the detection limit of the former method was two times higher. This colorimetric method can permit analysis of pharmaceutical products containing either SCC or DOSS. Phosphatidylcholine (lecithin) can also be determined using this method.     

Aggregation behaviour of a novel series of polyamidoamine-based dendrimers in aqueous solution

Dendrimers composed of G1 polyamidoamine branched with poly(propylene oxide) (PPO)-block-poly(ethylene oxide) (PEO) were synthesised for the first time. Surface tension results showed an increase in the critical aggregation concentration (cac) with PPO-b-PEO chain lengthening. The thermodynamic parameters associated with aggregate formation were determined by isothermal titration microcalorimetry, indicating that both the cac and the Gibbs free energy for aggregation (ΔG°) ascended as the amphiphilic chain length increased. The gain of entropy (ΔS°) was the main contribution to aggregation due to TΔS° being larger than the enthalpy (ΔH°). Aggregate morphology and size distribution were studied through transmission electron microscope and dynamic light scattering measurements. Furthermore, the relationship between PEO chain length and aggregation behaviour was discussed.     

Protein–Nanoparticle Interaction‐Induced Changes in Protein Structure and Aggregation

Large surface area, small size, strong optical properties, controllable structural features, variety of bioconjugation chemistries, and biocompatibility make many different types of nanoparticles (NPs), such as gold NPs, useful for many biological applications, such as biosensing, cellular imaging, disease diagnostics, drug delivery, and therapeutics. Recently, interactions between proteins and NPs have been extensively studied to understand, control, and utilize the interactions involved in biomedical applications of NPs and several biological processes, such as protein aggregation, for many diseases, including Alzheimer's disease. These studies also offer fundamental knowledge on changes in protein structure, protein aggregation mechanisms, and ways to unravel the roles and fates of NPs within the human body. This review focuses on recent studies on the roles and uses of NPs in protein structural changes and aggregation processes.     

可聚合型琥珀酸聚氧乙烯醚酯磺酸钠的合成与性能

以马来酸酐、烷基醇及烷基酚聚氧乙烯醚、氯代烯烃、亚硫酸氢钠为主要原料,经过单酯化、双酯化、磺化反应合成了两系列具有非离子结构的琥珀酸双酯磺酸钠阴离子型可聚合表面活性剂——琥珀酸聚氧乙烯醚酯磺酸钠,并测试了性能和进行聚合反应。经IR和1H NMR表征,目标化合物均符合相应的结构特征。与传统表面活性剂相比,两系列目标化合物均具有较低的临界胶束浓度(0.17mol/m3~0.32mol/m3),较低的表面张力(34.70mN/m~40.20mN/m),目标化合物发泡力和分散力大大提高,而乳化力稍有下降;在乳液聚合中,使用琥珀酸聚氧乙烯醚酯磺酸钠既能提高乳液的固含量又能使乳液粒子的粒径更小,分布更窄。     

Mimicking enzymes: cooperation between organic functional groups and metal ions in the cleavage of phosphate diesters

A series of ligands derived from the bis-2-pyridinylmethylamine structure, which bear either additional hydroxyl or aromatic amino groups, were prepared and their Zn(II) complexes were studied as catalysts for the cleavage of bis-p-nitrophenyl phosphate (BNP) and 2-hydroxypropyl-p-nitrophenyl phosphate (HPNP) diesters. A comparative kinetic study indicated that the insertion of organic groups, capable of acting as nucleophiles or as hydrogen-bond donors, substantially increases the hydrolytic activity of the metal complex. Dissection of the effects of the individual groups revealed that the increase in reactivity can reach up to three orders of magnitude. The improved efficiency of the systems studied, combined with the benefits resulting from the low pK(a) value of the active nucleophile, result in an acceleration of the BNP cleavage at pH 7 of six orders of magnitude. The pH-dependent reactivity profiles follow a bell-shaped curve and the maximum reactivity is observed at pH 9. The mechanism of the reactions and the structure of the complexes were investigated in detail by means of kinetic analysis, NMR spectroscopy experiments, and theoretical calculations. The reactivity of the complexes that cleave HPNP closely resembles the reactivity observed for BNP, but the accelerations achieved are lower as a result of different reaction mechanisms.     

疏水亲脂作用驱动的有机分子的簇集和自卷

疏水亲脂相互作用(HLI)是一种重要的分子间弱作用力,本文主要介绍了HLI驱动下的有机分子分子的簇集和自卷的研究进展,作者实验室发展的一些新的概念、影响有机分子簇集和自卷的各种因素和运用这些概念对一些疾病产生原因的解释。     

Studies on the photophysical characteristics of poly(carboxylic acid)s bound protoporphyrin IX and metal complexes of protoporphyrin IX

The copolymers of methacrylic acid with protoporphyrin IX (PPIX) and the metal complexes, zinc protoporphyrin IX and magnesium protoporphyrin IX were synthesised and characterised. Corresponding acrylic acid copolymers were also synthesised. The steady state absorption and fluorescence spectral properties of the macromolecular bound fluorophores PPIX, Zn-PPIX and Mg-PPIX were investigated. Poly(methacrylic acid) bound protoporphyrin IX, zinc protoporphyrin IX and magnesium protoporphyrin IX show an increase in the fluorescence intensity and lifetime with increase in the pH in the range 2-8 with a marked transition around pH 6.0-7.0. The fluorophore concentration in the dilute solution of the copolymers is micromolar and the fluorophore to the carboxylic acid monomer ratios in the copolymer is around 10⁻³. The molecular weight of the copolymers is 100 ± 10 kD. The fluorescence decay curves of all the fluorophore bound polymers follow biexponential decay fit independent of pH. Poly(MAA-co-PPIX) and poly(MAA-co-MgPPIX) undergo well marked pH induced structural transitions in the pH range of 6.0-7.0 whereas poly(MAA-co-ZnPPIX) undergoes pH induced structural transitions in the pH range of 4.0. In the case of polyacrylic acid copolymers the changes observed in the steady state and time resolved fluorescence studies are less marked. The distinct hydrophobic and hydrophilic environments experienced by the fluorophore bound to PMMA are attributed to the dynamics of the macromolecules in dilute aqueous solutions manifested by the α-methyl group present in the copolymer. The studies carried out using the fluorophores in the time windows from 2 ns to 12 ns indicate evolving trends in the dynamic coiling and reverse coiling of poly methacrylic acid chain.     

Thionation of phosphoramidodichloridates and phosphoramidate diesters using phosphorus pentasulfide and hexamethyldisiloxane under microwave irradiation. Part 1

A new, mild, efficient, and solvent-free microwave promoted synthesis of thiophosphoramidodichloridates and thiophosphoramidate diesters is described. The thionation reaction was accelerated with microwave irradiation using the combination of P₄S₁₀ and HMDO. The conversion of PO to PS by this method gave the desired product in higher yields and shorter reaction times as compared to conventional methods.     

Aggregation Behavior of Poly(Acrylic acid-co-Octadecyl Methacrylate) and Bovine Serum Albumin in Aqueous Solutions

Polymer-protein complexing systems have been extensively studied because of their wide application in biomedicine and industry. Here, we studied the aggregation behavior of the hydrophobically associating water-soluble polymer poly(acrylic acid-co-octadecyl methacrylate) [P(AA-co-OMA)] prepared with nonionic surfactant as an emulsifier and bovine serum albumin (BSA) in aqueous solution. We identified the optimal composite conditions of P(AA-co-OMA) and BSA aqueous solution. We measured the zeta potential, dynamic light-scattering particle size, and surface tension of P(AA-co-OMA) and BSA mixed aqueous solution. The results showed that the aggregation behavior between the polymer and BSA relied mainly on the hydrophobic interactions between the molecules. In addition, the best compounding condition was 8 wt.% of P(AA-co-OMA) content. The structure of hydrophobically associating polymer P(AA-co-OMA) and its aggregation with BSA were characterized by Fourier-transform infrared spectroscopy. The infrared spectroscopy results identified the hydrogen bonding behavior of the amino and carboxyl groups between the polymer and BSA. This behavior was also confirmed using thermogravimetric analysis and differential scanning calorimetry. The thermal decomposition temperature and melting temperature of BSA changed before and after it was combined with the polymer. We measured the morphology of the polymer BSA aggregate with 8 % polymer content by transmission electron microscopy. The binding mechanism was investigated, as well.     

Rational Topological Design for Fluorescence Enhancement upon Aggregation of Distyrylfuran Derivatives

A series of 2,5‐distyrylfuran derivatives bearing pentafluorophenyl‐ and cyanovinyl units have been synthesized for aggregation‐induced emission (AIE). The effect of the type and extent of the supramolecular connections on the AIE of the furan derivatives were examined and correlated with their X‐ray crystal structures. It was found that the simultaneous presence of cyano and perfluorophenyl units strongly enhances the fluorescence upon aggregation. Single‐crystal X‐ray diffraction analysis confirmed that C?H???F, F???F, C?H???nitrile, Ar???Ar_F (Ar=aryl, Ar_F=fluoroaryl), and nitrile???Ar_F intra‐ and intermolecular interactions drive the topology of the molecule and that solid‐state supramolecular contacts favor AIE of the furan derivatives.     

Aggregation and disaggregation of Aeromonas gum in an aqueous solution under different conditions

The aggregation and disaggregation of Aeromonas (A) gum, an acidic heteropolysaccharide, were investigated by viscometry, a fluorescent probe, and gel permeation chromatography combined with laser light scattering techniques in aqueous solutions containing desired NaCl at different temperatures. The A gum had a strong tendency of aggregation and high viscosity in the aqueous solutions. The weight‐average molecular weight, z‐average radius of gyration, weight‐average molar number (w_ag), and apparent aggregation number (N_ap) of the aggregates were investigated and discussed. The results indicated that there were three regions that corresponded to three kinds of aggregates and two transition temperatures at about 35 and 75 °C in the disaggregation course. When the temperature was higher than 75 °C, the w_ag hardly changed, and there was still a certain amount of aggregates even at 100 °C, indicating that the aggregates were difficult to disrupt completely. Moreover, the aggregation was thermally irreversible. Decreasing polysaccharide concentration reduced the content of the aggregate. However, N_ap remained constant around 20, independent of the polysaccharide concentration in a 0.5 M NaCl aqueous solution at 25 °C. At a salt concentration greater than or equal to 0.05 M, the aggregation was almost independent of the salt concentration used here. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2644–2651, 2000     

固相萃取-气相色谱-质谱法分析尿液中邻苯二甲酸单酯和双酯

建立了固相萃取-气相色谱-质谱测定尿液中邻苯二甲酸单酯和双酯的分析方法。尿液经 β-葡萄糖苷酸酶酶解后进行固相萃取净化,用乙腈、乙酸乙酯和乙醚-正己烷(1: 19, v/v)分别洗脱,合并洗脱液,氮气吹干后,用N,O-双三甲基硅基三氟乙酰胺(BSTFA)对邻苯二甲酸单酯进行硅烷化处理,使用气相色谱-质谱法检测。邻苯二甲酸单酯和双酯的线性范围为5~1000 μ g/L,检出限为0.3~1.1 μ g/L,回收率为77.9%~97.7%,相对标准偏差为3.7%~10.9%。应用该方法对50份尿液进行检测,检出邻苯二甲酸二(2-乙基己基)酯(DEHP)等7种邻苯二甲酸单酯和双酯类物质,平均质量浓度为6.0~142.7 μ g/L。该方法准确、可靠、灵敏度高,适用于尿液中邻苯二甲酸单酯和双酯的同时测定。     

Aggregation Effects in Visible‐Light Flavin Photocatalysts: Synthesis,Structure, and Catalytic Activity of 10‐Arylflavins

A series of 10‐arylflavins (10‐phenyl‐, 10‐(2′,6′‐dimethylphenyl)‐, 10‐(2′,6′‐diethylphenyl)‐, 10‐(2′,6′‐diisopropylphenyl)‐, 10‐(2′‐tert‐butylphenyl)‐, and 10‐(2′,6′‐dimethylphenyl)‐3‐methylisoalloxazine ( 2 a – f )) was prepared as potentially nonaggregating flavin photocatalysts. The investigation of their structures in the crystalline phase combined with ¹H‐DOSY NMR spectroscopic experiments in CD₃CN, CD₃CN/D₂O (1:1), and D₂O confirm the decreased ability of 10‐arylflavins 2 to form aggregates relative to tetra‐O‐acetyl riboflavin ( 1 ). 10‐Arylflavins 2 a – d do not interact by π–π interactions, which are restricted by the 10‐phenyl ring oriented perpendicularly to the isoalloxazine skeleton. On the other hand, N3? H???O hydrogen bonds were detected in their crystal structures. In the structure of 10‐aryl‐3‐methylflavin ( 2 f ) with a substituted N3 position, weak C? H???O bonds and weak π–π interactions were found. 10‐Arylflavins 2 were tested as photoredox catalysts for the aerial oxidation of 4‐methoxybenzyl alcohol to the corresponding aldehyde (model reaction), thus showing higher efficiency relative to 1 . The quantum yields of 4‐methoxybenzyl alcohol oxidation reactions mediated by arylflavins 2 were higher by almost one order of magnitude relative to values in the presence of 1 .     

原卟啉原IX的构象分析

在合理药物设计方法中 ,当靶标酶的三维结构未知时 ,对其底物进行构象分析 ,特别是确定其活性构象 ,对阐明靶标酶活性中心的空间形状和作用位点具有十分重要的意义。我们曾利用距离比较法确定了原卟啉原氧化酶的底物—原卟啉原IX的活性构象 ,本文从构象分析的角度对 4种不同构象的原卟啉原IX分子与二苯醚类分子的晶体学构象进行了几何参数的比较和分析 ,结果进一步证实了距离比较法所确定的活性构象更为可靠