杯芳烃的分子设计(Ⅵ)--一种新的杯[4]磺胺衍生物的合成及晶体结构

杯芳烃是由酚单体通过亚甲基在羟基邻位桥连而成的环状低聚物, 它具有可调的杯状疏水空腔, 结构柔性较大, 构象可变, 并对中性分子和有机、无机离子具有选择性配位能力. 因此, 在其上下缘进行化学修饰所得到的杯芳烃衍生物可广泛应用于萃取分离、离子选择性电极、色谱分析、功能材料、催化及模拟酶等研究领域[1～4].     

配合物[Ni(qina)_2(H_2O)_2]的合成及结构

近年来,晶体分子结构在设计和组装各种光、电磁离子交换、催化等新型功能材料方面受到广泛关注[1-5].在分子体系形成的过程中,配位键构成分子主体,而氢键、π-π堆积和金属-金属等弱相互作用则是分子之间构筑成超分子结构的稳定因素[6-8].喹哪啶酸(qina)具有鳌合配位能力和疏水性能,其配合物往往通过π-π堆积形成超分子化合物[9].     

π-共轭体系超分子自组装

π-共轭体系因其分子结构的可设计性以及优异的光电性质得到了广泛的研究,其超分子自组装在制备结构复杂、规则的功能纳米材料方面表现出了显著的优势,且是调控材料宏观性质的一种有效的方法.因此,π-共轭体系超分子自组装已经成为近年来信息、材料、生物等前沿领域的研究热点.本文综述了π共轭体系超分子自组装的机理、外界环境的导向作用、自组装形态以及其在光电器件、生物传感等方面的应用研究,进一步提出了该领域尚待解决的问题并对其应用前景进行了展望.     

碳纳米材料的超分子表面修饰及应用

目前碳纳米材料已经成为纳米科学研究中的热点,它的特殊结构使其具有特殊的物理化学性能,对其进行超分子修饰可以提高其分散性以及赋予其新的性能,已经引起研究人员的广泛兴趣.本文综述了近年来碳纳米材料的超分子修饰以及其应用研究.重点阐述碳纳米管和石墨烯通过不同的超分子作用,如pi-pi相互作用、疏水相互作用、氢键相互作用、静电相互作用等进行修饰制备具有不同功能的超分子碳纳米材料,以及在光电材料、药物和基因传输以及化学生物传感器等领域的应用.     

准轮烷和轮烷研究新进展

准轮烷和轮烷是一个在超分子化学中非常活跃的新领域.它们具有的特殊结构决定了准轮烷和轮烷在纳米功能材料和分子机器等方面有很大的应用潜力,因此倍受化学家们的关注.根据形成轮烷和准轮烷时主要驱动力的不同,可将轮烷和准轮烷的制备方法分为统计学缠绕、化学转移、受氢键驱动、受亲水-疏水相互作用驱动、受金属配位作用驱动、和受π-π堆积相互作用以及电荷转移驱动等.本文分别从上述几种驱动力的角度综述了近年来准轮烷和轮烷在合成和应用方面的最新研究进展.     

氮化碳及其复合材料在样品前处理领域的应用

氮化碳(g-C_3N_4)是一种新型二维碳纳米材料,目前已在催化降解、生物传感、能源存储和生物医药等领域得到了广泛应用。g-C_3N_4材料结构中丰富的含氮官能团和电子离域特性,赋予其独特的理化性质,使之能够与一些离子或分子产生络合、疏水、π-π键、氢键和静电力等相互作用。此外,g-C_3N_4材料比表面积大、性质稳定且制备简单,价格低廉,在样品前处理领域展现出良好的应用潜力。近几年,基于g-C_3N_4材料的样品前处理新方法不断涌现,该文总结了g-C_3N_4及其复合材料在固相萃取、磁性固相萃取和固相微萃取等领域的应用并进行了展望。     

超分子凝胶的手性功能应用:手性分子识别与不对称催化

超分子凝胶通过形成三维空间网络结构将溶剂液体相固定化,是一类重要的软物质材料。由于超分子凝胶能快速形成,自组装形成的纳米结构均一、可调,且可大规模制备,因此成为超分子化学、纳米技术以及材料科学研究的重要研究方向之一,并在诸多领域得到广泛的功能研究和应用拓展,如在材料模板、光电开关、药物释放、分子识别和超分子催化等方面已有大量研究报道。由于超分子凝胶具有固-液相可逆转变、可控组装等特性,成为了超分子手性和分子手性研究的重要载体。近年来超分子凝胶在超分子手性催化、手性分子识别等方面取得了一系列重要突破,为超分子凝胶功能应用开辟了新的空间,为手性科学研究提供了新的手段和方法。     

卤键在超分子化学中的应用进展

卤键是指作用在卤原子(路易斯酸)和具有孤对电子的原子或π电子体系(路易斯碱)之间的新型弱相互作用,其在超分子多维自组装和分子识别(如超分子催化、超分子选择拆分、超分子传感)等领域有着广泛的应用。本文介绍了卤键的类别、特性、功能及在超分子化学结构与功能领域中的应用。     

6-羟基染料木素与8-羟基染料木素的制备及生物活性研究进展

6-羟基染料木素(6-OHG)和8-羟基染料木素(8-OHG)是染料木素A环上C6或C8位发生羟基化反应生成的衍生物,其分子中有更多酚羟基,同时含有邻二酚羟基结构,这也使它们的生物活性与染料木素相比发生了显著变化。研究表明,6-OHG和8-OHG具有抗氧化、抗诱变、抑制磷酸二酯酶3B活性、抗糖化、保肝、抗黑色素生成作用、改善记忆力等广泛的药理活性。本文将对6-OHG和8-OHG的来源、制备方法和生物活性研究进行综述,以期为两个化合物的开发利用提供参考。     

功能化分子印迹Fe_3O_4磁性复合材料的研究进展

功能化分子印迹Fe_3O_4磁性复合材料是通过分子印迹技术在磁性颗粒表面进行功能化修饰得到兼具特异性识别性和超顺磁性的无机-有机杂化材料。该类材料因其具有高选择性、大吸附容量,在磁场中的定向移动性和疏水亲水可调控性等特异性能已成为国内外研究的重要方向,在食品安全、环境检测和生物医学等领域有广泛的应用前景。本文综述了近年来该类新型材料的制备、表征及应用方面的研究进展,并对该领域面临的挑战和前景作一展望。     

Tuning the porosity of triangular supramolecular adsorbents for superior haloalkane isomer separations

Distillation-free separations of haloalkane isomers represents a persistent challenge for the chemical industry. Several classic molecular sorbents show high selectivity in the context of such separations; however, most suffer from limited tunability or poor stability. Herein, we report the results of a comparative study involving three trianglamine and trianglimine macrocycles as supramolecular adsorbents for the selective separation of halobutane isomers. Methylene-bridged trianglamine, TA, was found to capture preferentially 1-chlorobutane (1-CBU) from a mixture of 1-CBU and 2-chlorobutane (2-CBU) with a purity of 98.1%. It also separates 1-bromobutane (1-BBU) from a mixture of 1-BBU and 2-bromobutane (2-BBU) with a purity of 96.4%. The observed selectivity is ascribed to the thermodynamic stability of the TA-based host–guest complexes. Based on single crystal X-ray diffraction analyses, a [3]pseudorotaxane structure (2TA⊃1-CBU) is formed between TA and 1-CBU that is characterized by an increased level of noncovalent interactions compared to the corresponding [2]pseudorotaxane structure seen for TA⊃2-CBU. We believe that molecular sorbents that rely on specific molecular recognition events, such as the triangular pores detailed here, will prove useful as next generation sorbents in energy-efficient separations.

The methylene-bridged trianglamine (TA) can selectively capture 1-chlorobutane from a mixture of 1-chlorobutane and 2-chlorobutane due to the greater thermodynamic stability of the TA-based host–guest complex formed with 1-chlorobutane.     

Amphiphilic and mesomorphic fullerene-based dendrimers

Growing attention is currently devoted to large dendritic structures for applications in nanotechnology and materials science. In this respect, the incorporation of such compounds into thin ordered films appears to be an important issue. One of the most widely pursued approaches to structurally ordered dendrimer assemblies has been the preparation of Langmuir films at the air-water interface. We report on the case of a diblock globular fullerene-based dendrimer and show that peripheral substitution of the dendrimer with hydrophobic chains on one hemisphere and hydrophilic groups on the other provides the required hydrophobic/hydrophilic balance allowing the formation of stable Langmuir films. A second approach has been to consider the case of fullerene containing dendrimers terminated by mesogenic groups such as cyanobiphenyl subunits. Whatever the generation is, up to the fourth one, all these compounds exhibit a well-defined liquid crystalline smectic A phase. The molecular organisation within the smectic layers is found to be monolayered or bilayered depending on the generation. For the smallest dendrimers, the organisation is mainly governed by the size of the fullerene moiety, whereas for the higher ones, it is governed by the interactions between the terminal mesogenic groups. These two approaches appear particularly interesting for functional groups such as fullerenes, which are not well adapted to be organised in nanoscale architectures. The present study shows that fullerenes can indeed be introduced into different types of ordered structure when they have been chemically adequately modified.     

Noncovalent water-based materials: robust yet adaptive

The adaptive properties of noncovalent materials allow easy processing, facile recycling, self-healing, and stimuli responsiveness. However, the poor robustness of noncovalent systems has hampered their use in real-life applications. In this Concept Article we discuss the possibility of creating robust noncovalent arrays by utilizing strong hydrophobic interactions. We describe examples from our work on aqueous assemblies based on aromatic amphiphiles with extended hydrophobic cores. These arrays exhibit fascinating properties, including robustness, multiple stimuli-responsiveness, and pathway-dependent self-assembly. We have shown that this can lead to functional materials (filtration membranes) rivaling covalent systems. We anticipate that water-based noncovalent materials have the potential to replace or complement conventional polymer materials in various fields, and to promote novel applications that require the combination of robustness and adaptivity.     

Single-molecule force spectroscopy of β-peptides that display well-defined three-dimensional chemical patterns

Oligomers of β-amino acids ("β-peptides") can be designed to fold into stable helices that display side chains with a diverse range of chemical functionality in precise arrangements. We sought to determine whether the predictable, three-dimensional side-chain patterns generated by β-peptides could be used in combination with single-molecule force spectroscopy to quantify how changes in nanometer-scale chemical patterns affect intermolecular interactions. To this end, we synthesized β-peptides that were designed to be either globally amphiphilic (GA), i.e., display a global segregation of side chains bearing hydrophobic and cationic functional groups, or non-globally amphiphilic (iso-GA), i.e., display a more uniform distribution of hydrophobic and cationic functional groups in three-dimensions. Single-molecule force measurements of β-peptide interactions with hydrophobic surfaces through aqueous solution (triethanolamine buffer, pH 7.2) reveal that the GA and iso-GA isomers give rise to qualitatively different adhesion force histograms. The data are consistent with the display of a substantial nonpolar domain by the GA oligomer, which leads to strong hydrophobic interactions, and the absence of a comparable domain on the iso-GA oligomer. This interpretation is supported by force measurements in the presence of methanol, which is known to disrupt hydrophobic interactions. Our ability to associate changes in measured forces with changes in three-dimensional chemical nanopatterns projected from conformationally stable β-peptide helices highlights a contrast between this system and conventional peptides (α-amino acid residues): conventional peptides are more conformationally flexible, which leads to uncertainty in the three-dimensional nanoscopic chemical patterns that underlie measured forces. Overall, we conclude that β-peptide oligomers provide a versatile platform for quantifying intermolecular interactions that arise from specific functional group nanopatterns.     

Coatings based on mucin‐tannic acid assembled multilayers. Influence of pH

Although widely used as implantable materials due to their mechanical properties, metal devices show several disadvantages, such as the lack of cellular binding sites, antibacterial properties, or lubricant properties. To this end, the development of engineered surfaces through protein coatings has been largely investigated. Due to their natural origin and complex structure which allows the formation of hydrogels, mucins have been proposed and investigated as effective coatings for metallic implants. The present study evaluates the ability of porcine gastric mucin (PGM) to form stable coatings on a model metal surface, using three buffers with different pH values, ranging from acid to alkaline, as dispersion media. Considering its large number of hydroxyl groups and its ability to form hydrogen bonds with the protein, tannic acid (TA) was used as cross‐linker. In addition to coatings' thickness and elasticity assessed through Quartz Crystal Microbalance with Dissipation monitoring (QCM‐D), the study also evaluates the interactions between PGM and TA at various pH values of the dispersion media through DLS. The corroborated results show that the neutral pH allows the best interactions between PGM and TA leading to the formation of a stable, less elastic coating when compared with that obtained using as dispersion media the other two investigated buffers. Moreover, the hydrophilicity and mechanical properties of the dried coatings were assessed through contact angle measurements and nanoindentation, respectively.     

Liquid chromatography on unmodified and modified Spheron gels III. Phenolic compounds

Summary Chromatographic behaviour of phenolic compounds is studied on the ethyleneglycol methacrylate gel Spheron and on ion-exchangers produced by the chemical modification of this gels (cation exchanger Spheron S and anion exchanger Spheron DEAE) as compared to octadecyl silica. The hydrophobic effects obviously predominate in the retention mechanism on Spherons in aqueous methanolic mobile phases, but a selectivity differring from the behaviour on octadecyl silica was found for a number of phenolic compounds This is due to interactions with the functional groups in the unmodified and modified Spheron materials and may be utilized for the separation of phenols by liquid chromatography.     

Bcl-2蛋白抑制剂结合腔的性质分析

采用多重拷贝同时搜寻(MCSS)等方法对Bcl-2蛋白抑制剂结合腔进行分析. 结果显示, 结合腔可分成P1, L1, P2, P3和P4等5个区域, 其底部呈疏水性, 而P3部位不适合芳香性大基团的结合. 结合腔侧面和边缘处分布有可与配体形成除疏水以外作用的多个重要残基. MCSS计算得到的各种性质官能团在结合腔内的能量优势位置和取向能与已知结合模式的高活性抑制剂的重要基团位置吻合得较好.     

Binding of erbium(III) and holmium(III) to native and chemically modified alfalfa biomass: a spectroscopic investigation

Traditional treatment methods used to clean-up heavy metal contamination of soils and waters are cost intensive whereas more cost effective methods need to be developed. The use of plant materials to remediate heavy contamination has been studied for the past two decades. This technique has shown much promise for many of the common heavy metal contaminants, but few studies have focused on the lanthanide series elements. By investigating the binding and interactions of the lanthanide elements to alfalfa biomass, a more complete understanding of the binding mechanisms and the interactions of heavy metals with biomaterials can be obtained. Different chemical functional groups on the alfalfa biomass, carboxyl, amino, sulfur, and ester groups, were modified to investigate the binding mechanisms of erbium(III) and holmium(III). Batch experiments were performed with native and chemically modified alfalfa biomass suggesting that the carboxyl groups play a major role in the binding of erbium(III) and holmium(III) to the alfalfa biomass. In addition, X-ray absorption spectroscopy (XAS) studies corroborated the data obtained from the batch experiments.     

Effects of a lysophosphatidylcholine and a phosphatidylcholine on the morphology of taurocholic acid-based mixed micelles as determined by small-angle X-ray scattering

We previously showed that Caco-2 cell absorption of β-carotene from taurocholic acid (TA)-based mixed micelles differed depending on the composition of the micelles. In this study, the shapes and sizes of TA-based mixed micelles, that is, mixed micelles of TA, 1-oleoyl-rac-glycerol (MG), oleic acid (OLA), and either 1-palmitoyl-sn-glycero-3-phosphocholine (MPPC; i.e., a lysophospholipid) or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC; i.e., a phospholipid) (60:3:1:0.75–12) were determined by using small-angle X-ray scattering (SAXS). We found that increasing the ratio of MPPC in mixed micelles of TA, MG, OLA, and MPPC was responsible for the previously observed enhanced β-carotene absorption by Caco-2 cells and changed the micelle shape from core–shell spherical to core–shell ellipsoidal. In contrast, increasing the ratio of POPC in mixed micelles of TA, MG, OLA, and POPC was responsible for the suppressed β-carotene absorption by the cells, changed the micelle shape from core–shell spherical to core–shell ellipsoidal to core–shell cylindrical, and caused a rapid increase in micelle volume. These results will be useful for understanding the mechanisms that mediate β-carotene absorption by cells and for developing technologies to improve the intestinal absorption of lipophilic components of drugs and nutrients.     

Insights into the self-directed structuring of hybrid organic-inorganic silicas through infrared studies

Fourier transform infrared (FTIR) spectroscopy has been used to probe the organization of the organic fragments in lamellar bridged silsesquioxanes with organic substructures based on alkylene chains of various lengths and urea groups [O1.5Si(CH2)3NHCONH(CH2)nNHCONH(CH2)3SiO1.5] (n = 6, 8-12). The structure and intermolecular interactions (hydrophobic and H-bonding) of these well-defined self-structured hybrid silicas are discussed in relation to their powder X-ray diffraction patterns. The degree of structural order is determined by the length and parity of the alkylene spacer. A concomitant enhancement in the degree of condensation of the inorganic component and a decrease in the strength of the hydrophobic interactions between the organic components are demonstrated. The strength and directionality of the H-bonding are directly correlated to the crystalllinity of the organic-inorganic hybrid materials.