奇偶效应诱导的苯丙氨酸类水凝胶手性反转

为了模拟生物大分子(如DNA和蛋白质等)螺旋手性反转的现象,设计合成了4种酰胺基或脲基共价连接L-苯丙氨酸和苯环,外围为二甘醇胺与3-氨基-1,2-丙二醇的C2对称小分子凝胶因子,利用酰胺基(CONH)与脲基(NHCONH)之间的奇偶效应实现了超分子螺旋手性的反转.通过核磁共振波谱仪(1H-NMR和13C-NMR),高分辨质谱仪(HRMS)对凝胶因子结构和分子量进行了分析表征.并运用圆二色光谱(CD)、扫描电子显微镜(SEM)、紫外可见吸收光谱(UV-Vis)和红外光谱(FTIR)对其组装纤维结构和组装方式进行研究.实验结果表明酰胺基(CONH)与脲基(NHCONH)之间的奇偶效应改变凝胶因子的组装方式,调控了超分子手性特征,实现了超分子水凝胶螺旋手性的反转.     

超分子金属凝胶

近年来,超分子凝胶已逐渐发展为一类具有广阔应用前景的智能/功能性纳米材料。目前研究的大部分超分子凝胶利用的是氢键或者分子堆积作用,而配位键这一在超分子化学中同样重要的作用在凝胶合成上的应用则远远不足。由于引入金属离子后能够给凝胶带来光电、催化、氧化还原等新的性能,因此超分子金属凝胶的研究也在近年来得到升温。本文首先给出超分子金属凝胶的定义,接着通过实例具体介绍基于凝胶因子和配位聚合物两种形式的超分子金属凝胶,将分子结构特别是其中的配体基团、所用金属离子和凝胶的性质、功能联系起来,最后简介异常的超分子金属凝胶行为。     

基于三萜骨架的超分子凝胶体系

基于有机小分子多级自组装形成的超分子凝胶,由于其潜在的应用前景越来越受到人们的关注。合理设计凝胶因子并实现在适当的溶剂中自组装形成纤维状结构,对于分子识别和自组装来说都有一定挑战。三萜化合物具有独特的手性骨架结构,是一类重要的生物活性天然产物,在消炎、降血脂、保肝护肾、抗菌、抗肿瘤、抗真菌等方面有着重要的药用价值。近年来,基于独特的手性刚性骨架和具有多个可修饰位点的特点,此类化合物的聚集性质和在超分子组装方面的应用已经引起关注。本文总结了未经修饰的五环三萜化合物的聚集组装性质和基于此类骨架的功能分子在超分子凝胶方面的研究,并介绍了此类超分子凝胶潜在的应用。结果表明,发展基于此类天然产物骨架的超分子组装体,不仅为超分子凝胶的研究引入新的构筑基元,并且能够达到阐述生物活性分子之间相互作用力以及充分利用自然界资源创造新材料的目的。     

基于低分子量凝胶因子的超分子水凝胶：从结构到功能*

基于低分子量凝胶因子的超分子水凝胶由于其良好的刺激相应性及生物相容性,在智能凝胶、组织工程等方面有广泛的应用前景。而凝胶因子的设计制备与凝胶机理的研究已成为其发展的关键,本文在介绍超分子凝胶的基本概念的基础上,综述了超分子水凝胶近期的研究进展,主要介绍了凝胶因子的种类及超分子水凝胶的应用,并对超分子凝胶领域的国内外研究现状及前景进行了评述。     

[60]富勒烯的超分子自组装研究进展

超分子自组装是发展超分子电子学的重要途径。随着纳米科学和技术的迅速发展,自组装技术已成功地应用于纳米尺度物质的维数、形貌和功能等的调控。作为构筑分子水平上一维、二维、三维有序功能结构和高有序分子聚集态结构的关键技术,超分子自组装技术有力地推动了具有优良光、电、磁性能的分子材料和纳米功能材料更深层次的研究。本文综述了超分子自组装在富勒烯科学领域的基础研究和应用,特别是对有利于自组织和自组装功能的富勒烯基衍生物的设计与合成、超分子作用力引导的具有特定结构的分子体系的可控自组装、以及富勒烯分子聚集态结构材料的光物理过程、超分子中电子转移和能量转移现象进行了描述;并对卟啉、四硫富瓦烯、碗烯和杯芳烃等一系列富π电子化合物和大环主体分子等包含[60]富勒烯的主体化合物的超分子作用和超分自组装体以及通过氢键、π-π作用、静电力和范德华力和金属配位作用形成的[60]富勒烯超分子自组装体进行了总结,对未来发展进行了展望。     

环糊精超分子凝胶的构筑及其功能

环糊精作为一种具有良好的水溶性和生物兼容性的大环主体,因其对无机、有机和生物底物的特异性键合而倍受关注。凝胶材料则凭借其结合了固体弹性以及液体流动性等特性而有着广泛的应用。环糊精超分子凝胶融合了环糊精和凝胶的优势,在软材料领域研究中有着特殊的重要意义。本文从环糊精凝胶的构筑出发,从氢键、主-客体键合和离子相互作用等方面对其形成超分子凝胶的驱动力进行讨论,并对超分子凝胶在生物、检测、吸附及智能材料（包括滑动环类材料）领域的最新研究进展进行综述,为构筑新型环糊精超分子凝胶、开发该类凝胶的新功能提供参考。最后,对环糊精超分子凝胶的应用前景进行了展望。     

超分子凝胶中的光化学反应

超分子凝胶中的光化学反应是比较特殊的一类反应,通常是将具有光响应活性的基团或分子引入到超分子凝胶的自组装体系中,因此,能够将超分子凝胶独特的性质与光化学反应的优势有效地结合起来,构筑新型的光功能材料,这使得此类超分子凝胶在光信息存储、光开关及光转换器件等前沿领域具有广阔的应用前景.本文主要总结近年来国内外包括作者课题组对超分子凝胶中光化学反应方面的研究进展,以及其在多重响应凝胶、手性光学开关以及手性合成方面的应用.     

含甲氧基偶氮苯液晶基元超分子的相行为研究

氢键是分子聚集和识别过程中的重要相互作用,利用分子间氢键,可设计并制备各种超分子体系材料,1989年,Kato等报道了吡啶基和羧酸基通过分子间氢键相互作用形成扩展液晶基元,得到了液晶稳定性增强的超分子液晶复合体系及侧链超分子液晶聚合物;同时,Lehn等报道了带脲嘧啶基和2,6-二酰胺吡啶基两种互补官能团的分子通过三重氢键缔合形成的主链超分子液晶。从此,迅速而广泛的开展利用氢键组装的超分子液晶体系的研究,并已组装合成出低分子型、     

基于偏苯三甲酸与对羟基吡啶复合物的超分子水凝胶

基于偏苯三甲酸和对羟基吡啶合成了一种具有支化结构的凝胶因子,采用氢核磁、红外光谱及元素分析确认其结构.该凝胶因子熔体在冷却时可拉出数厘米的长丝,表明分子间形成了强相互作用.将凝胶因子的水溶液分别在25℃和0℃下自然冷却、以及在25℃的超声作用下冷却,凝胶因子自组装成纤维状网络结构并使水凝胶化,纤维网络的密度及凝胶的稳定性均按上述凝胶形成条件顺序增加.通过干凝胶能谱面扫描分析发现氮元素主要处于纤维内部,表明两亲性凝胶因子对分子自组装的影响.通过分析邻苯二甲酸与对羟基吡啶复合物、偏苯三甲酸的单晶结构表明,凝胶因子基于多种氢键识别作用组装成纤维结构.干凝胶的粉末X射线衍射分析表明在凝胶化过程中凝胶因子沿着特定方向进行组装.     

聚合有机凝胶印迹膜对D-和L-苯丙氨酸的选择性吸附

以1-甲基-2,4-二(N’-十八烷脲基)苯为凝胶剂,以液体单体丙烯酸-2-乙基己酯、甲基丙烯酸甲酯、二甲基丙烯酸聚乙二醇(200)酯以及模版分子和光敏引发剂的混合物为溶剂,研究表明,这种二烷基脲型凝胶剂在这些单体混合物中可进行超分子自组装,形成互相缠绕的具有纳米尺寸的纤维状聚集体,最终导致这些单体混合物首先形成稳定的超分子有机凝胶。然后经UV光引发聚合,经乙醇抽提凝胶剂聚集体和模板分子,制备了一种新型分子印迹的聚合有机凝胶薄膜。探讨了不同凝胶剂浓度、模板分子浓度、单体混合物配比所制备的印迹聚合有机凝胶薄膜对D-和L-苯丙氨酸吸附效率的影响。结果表明所制备的印迹聚合超分子凝胶对L-苯丙氨酸吸附效率约为对D-苯丙氨酸吸附效率的3～4倍,表现出明显的选择性吸附性。     

Development and rheological investigation of novel alginate/N‐succinylchitosan hydrogels

In the present article alginate hydrogels and novel hydrogels based on blends of alginate/N‐succinylchitosan have been realized in water solution at neutral conditions. The gels have been obtained by crosslinking via the internal setting method using calcium carbonate (CaCO₃) as calcium ions source. A rheological investigation of both the plain alginate and the alginate/N‐succinylchitosan blend hydrogels has been performed by means of oscillatory dynamic measurements. The effect of the inclusion of different amounts of CaCO₃ on the critical deformation (γ_c) characterizing the limit of the linear viscoelastic regime has been studied for the plain alginate gels. The frequency response in small amplitude oscillatory experiments of the plain alginate gels has been investigated in terms of the storage (G′) and loss (G″) modulus behavior. The dynamic data have been interpreted in terms of the Friedrich and Heymann model. The inclusion of the N‐succinylchitosan, in the range 10–50% w/w, had no effect on the γ_c values. On the contrary, when the 10% w/w of the N‐succinylchitosan is added to the plain alginate gels, a significant increase in the storage modulus values is recorded for all the systems analyzed. The gelation kinetics has been investigated and the results indicate that the kinetics process can be accelerated increasing the percentage of Ca⁺² ions and/or including the N‐succinylchitosan in the plain alginate systems. Finally, the morphological analysis of scaffolds obtained from the hydrogels through freeze‐drying revealed an interconnected porous structure. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1167–1182, 2008     

Textural Characterization of Silica and Silica-Alumina Gels: Comparison of Different Techniques

The porous texture of silica and silica-alumina hydrogels has been studied by means of thermoporometry measurements. The texture of the xerogels resulting from spray-drying of silica-alumina hydrogels is then evaluated by different methods: BET, Hg-porosimetry and thermoporometry. As each method is based on different physical principles and assumptions, differences are observed between the results. However, these results are complementary and their comparison leads to a better knowledge of the texture of the catalyst particles. A good agreement is observed between thermoporometry and nitrogen adsorption-desorption measurements, whereas mercury porosimetry results are very different. Silica-alumina gels appear as mainly mesoporous materials.     

Self-Foaming Metal-Organic Gels Based on Phytic Acid and Their Mechanical,Moldable, and Load-Bearing Properties.

A catalogue of metal-organic gels are synthesized from phytic acid (PA) and a diversity of metal ions (Fe³⁺, Cr³⁺, Al³⁺, Ce³⁺, Y³⁺, Co²⁺, Ni²⁺, Mn²⁺, Cu²⁺, Zn²⁺, Mg²⁺) upon heating at 80 °C. PA−M gels have various morphologies, including irregular granular (PA−Fe, PA−Al, PA−Ce, PA−Cr, PA−Ni, PA−Co), spongy (PA−Y), and hollow tremella-like (PA−Cu) morphologies. Interestingly for PA−Fe-1 : 4 (PA:Fe³⁺=1 : 4) a large amount of gas is generated during the gelation process leading to a self-foaming gel. The PA−Fe-1 : 4 self-foaming gel shows reversible gel-sol phase transition. The gel is unusually weakened and transformed into a sol at room temperature, and the sol is reversed to gelation when heated again at 80 °C. PA−Fe-1 : 4 gel also shows shapeable and load-bearing properties, and it can bear up to 200 times of its weight, depending on the gas amount fixed in the foam gel and the aging time. This work provides a catalogue of self-foaming supramolecular gels with tunable properties based on naturally abundant resources.     

Combination of temperature ramp with holographic relaxation spectroscopy for investigation of gelatin gels

A new method of combining temperature ramp with holographic relaxation spectroscopy (TR-HRS) to investigate thermoreversible gels is reported. The gel melting temperature, gel content, and mobility of the gelatin molecules inside the gel networks can be simultaneously measured in one TR-HRS experiment.     

Phytic Acid-Based FeCo Bimetallic Metal-Organic Gels for Electrocatalytic Oxygen Evolution Reaction

Electrocatalysts have been developed to improve the efficiency of gas release for oxygen evolution reaction (OER), and finding a simple and efficient method for efficient electrocatalysts has inspired research enthusiasm. Herein, we report bimetallic metal-organic gels derived from phytic acid (PA) and mixed transition metal ions to explore their performance in electrocatalytic oxygen evolution reaction. PA is a natural phosphorus-rich organic compound, which can be obtained from plant seeds and grains. PA reacts with bimetallic ions (Fe³⁺ and Co²⁺) in a facile one-pot synthesis under mild conditions to form PA-FeCo bimetallic gels, and the corresponding aerogels are further partially reduced with NaBH₄ to improve the electrocatalytic activity. Mixed valence states of Fe(II)/Fe(III) and Co(III)/Co(II) are present in the materials. Excellent OER performance in terms of overpotential (257 mV at 20 mA cm⁻²) and Tafel slope (36 mV dec⁻¹) is achieved in an alkaline electrolyte. This reduction method is superior to the pyrolysis method by well maintaining the gel morphology structure. This strategy is conducive to the further improvement of the performance of metal-organic electrocatalysts, and provides guidance for the subsequent application of metal-organic gel electrocatalysts.     

超分子聚合物凝胶

作为非常重要的软物质材料,超分子聚合物凝胶代表了一个全新的概念和更复杂的凝胶体系.这种新型的超分子体系的构建,是基于多种非共价相互作用协同的多层次组装.即小分子构筑基元首先组装成为超分子聚合物,而这些非共价聚合物的多层次组装形成凝胶的纳米结构.超分子聚合物凝胶无论是在结构上,还是在性能上都具有很多崭新的特点.因此,尽管有关超分子聚合物凝胶的研究开展的时间还很短,这一体系所表现出的独特性以及巨大潜力已经引起科学家们越来越广泛的关注.本文简要综述了这一领域的最新进展.主要论述基于多种非共价相互作用的超分子聚合物凝胶的构建以及对其力学性能的调控.     

Smart nanocomposite polymer gels

The combination of polymers with nanomaterials displays novel and often enhanced properties compared to the traditional materials. They can open up possibilities for new technological applications. The magnetic polymer gel represents a new type of composites consisting of small magnetic particles, usually from the nanometer range to the micron range, dispersed in a highly elastic polymeric gel matrix. Combination of magnetic and elastic properties leads to a number of striking phenomena that are exhibited in response to impressed magnetic fields. Giant deformational effects, high elasticity, anisotropic properties, temporary reinforcement and quick response to magnetic field open new opportunities for using such materials for various applications.     

Transparent Organic/Inorganic Hybrid Gels: A Classification Scheme

An attempt is made to classify transparent organic/inorganic materials synthesized by the sol–gel process. The chemical structures of the hybrids are the main criteria for this classification. Three main types of organic/inorganic gels are distinguished and their basic physico-chemical characteristics are outlined. © 1997 by John Wiley & Sons, Ltd.     

Insights into the Formation and Structures of Molecular Gels by Diimidazolium Salt Gelators in Ionic Liquids or “Normal” Solvents

Insights are provided into the properties of molecular gels formed by diimidazolium salts both in “normal” solvents and ionic liquids. These materials can be interesting for applications in green and sustainable chemistry in which ionic liquids play a significant role, like catalysis and energy. In particular, two positional isomers of a diimidazolium cation have been examined with a wide range of anions for their ability to form gel phases. In particular, di‐, tri‐, and tetravalent anions bearing aliphatic or aromatic spacers were paired with the divalent cations. The properties of the organo‐ and ionogels formed have been analyzed by means of several different techniques, including calorimetry, rheology, resonance light scattering, UV/Vis absorption, polarizing optical microscopy, and powder X‐ray diffraction measurements. The investigations performed enabled us to obtain a wide range of conductive materials characterized by a high thermal stability and a low corrosiveness of the gelator (organogels) or of both gelator and solvent (ionogels). The information gained should be useful in the broader quest to identify and promote their applications.     

Stimuli‐Responsive Metallogels for Synthesizing Ag Nanoparticles and Sensing Hazardous Gases

A newly synthesized bis‐pyridyl ligand having a diphenyl ether backbone ( LP6 ) displayed the ability to form crystalline coordination polymers ( CP1‐CP6 ) which were fully characterized by single crystal X‐ray diffraction. Most of the resulting polymers were lattice‐occluded crystalline solids—a structural characteristic reminiscent to gels. The reactants of the coordination polymers produced metallogels in DMSO/water confirming the validity of the design principles with which the coordination polymers were synthesized. Some of the metallogels displayed material properties like in situ synthesis of Ag nanoparticles and stimuli‐responsive gel–sol transition including sensing hazardous gases like ammonia and hydrogen sulfide.