Regulation of substituent groups on morphologies and self-assembly of organogels based on some azobenzene imide derivatives

In this paper, new azobenzene imide derivatives with different substituent groups were designed and synthesized. Their gelation behaviors in 21 solvents were tested as novel low-molecular-mass organic gelators. It was shown that the alkyl substituent chains and headgroups of azobenzene residues in gelators played a crucial role in the gelation behavior of all compounds in various organic solvents. More alkyl chains in molecular skeletons in present gelators are favorable for the gelation of organic solvents. Scanning electron microscopy and atomic force microscopy observations revealed that the gelator molecules self-assemble into different aggregates, from wrinkle, lamella, and belt to fiber with the change of solvents. Spectral studies indicated that there existed different H-bond formations between amide groups and conformations of methyl chains. The present work may give some insight to the design and character of new organogelators and soft materials with special molecular structures.     

Spacer effect on nanostructures and self-assembly in organogels via some bolaform cholesteryl imide derivatives with different spacers

In this paper, new bolaform cholesteryl imide derivatives with different spacers were designed and synthesized. Their gelation behaviors in 23 solvents were investigated, and some of them were found to be low molecular mass organic gelators. The experimental results indicated that these as-formed organogels can be regulated by changing the flexible/rigid segments in spacers and organic solvents. Suitable combination of flexible/rigid segments in molecular spacers in the present cholesteryl gelators is favorable for the gelation of organic solvents. Scanning electron microscopy and atomic force microscopy observations revealed that the gelator molecules self-assemble into different aggregates, from wrinkle and belt to fiber with the change of spacers and solvents. Spectral studies indicated that there existed different H-bond formations between imide groups and assembly modes, depending on the substituent spacers in molecular skeletons. The present work may give some insight into the design and character of new organogelators and soft materials with special molecular structures.     

希夫碱凝胶因子的合成及压致变色性能研究

智能凝胶作为一种新型软材料对外界刺激具有独特的响应性,近年来受到人们的极大关注。以易于结构衍生化的2,4-（3,4-二氯苯亚甲基）-D-葡萄糖酸甲酯为平台分子,设计合成了新型智能希夫碱类凝胶因子化合物3a和3b。研究了凝胶因子在不同溶剂中的凝胶性能,并探索了机械力对于智能凝胶因子的影响。结果表明,凝胶因子的凝胶能力依赖于溶剂的种类和凝胶因子碳链的长度;通过原子力显微镜及场发射透射电镜可以观察到凝胶呈三维纤维网状结构。有趣的是,碳链较短的化合物3b具有压致变色性能,场发射扫描电镜和X-射线衍射表明压致变色是由于结晶态和无定型态聚集体结构的转变。     

含不对称碳原子的苯并吡喃-2-酮骨架化合物的液晶性和凝胶性能

对苯并吡喃-2-酮-6-基-4-烷氧基苯甲酸酯(1-n)的烷基链进行化学修饰,引入了不对称碳原子,合成了苯并吡喃-2-酮-6-基-4(S)-烷氧基苯甲酸酯(2 H-chromen-2-on-6-yl 4-(S)-alkoxy-benzo-ates,1-n*)化合物。研究了化合物1-n*的液晶性和凝胶性能。与化合物1-n相比,长碳链的化合物1-n*显示近晶A相。化合物1-n*能够同多种有机溶剂形成凝胶,测试了在各种溶剂中的临界凝胶浓度。扫描电子显微镜观察结果表明,干凝胶呈纤维状三维网络结构,化合物1-7*的凝胶纤维呈右旋结构,化合物1-8*的凝胶纤维则呈左旋结构与已报道的凝胶剂相比,凝胶剂1-n*具有化学结构简单、相对分子质量小、内酯骨架形状宽度大和偶极矩大的特点,偶极作用在增强凝胶性能方面起到重要的作用。     

烯丙基山梨醇凝胶因子的合成及凝胶性能研究

1, 3∶2, 4-二(对甲基苄叉)-D-山梨醇(MDBS)是一种凝胶能力突出的山梨醇缩醛类凝胶因子,对比MDBS本设计合成一系列烯丙基山梨醇缩醛,并通过凝胶因子之间的作用力、分子的几何构型及亲疏水作用等方面研究了凝胶因子在溶剂中的自组装及凝胶机理。考察了4种凝胶因子对30种常见有机溶剂的凝胶能力,以及凝胶因子在不同溶剂中的最低凝胶浓度。结果表明,凝胶因子的凝胶能力依赖于凝胶因子的分子结构,烯丙基的引入显著提高了凝胶因子的凝胶能力。研究了凝胶的形成机理,通过紫外光谱研究自组装力,通过场发射扫描电镜可以观察到凝胶呈纤维状和三维网状结构。     

DBS类凝胶因子的合成及性能

以取代的苯甲醛和山梨醇为原料,环己烷为溶剂和夹带剂,甲醇为促进剂,对甲苯磺酸为催化剂,用共沸脱水法合成了1,3∶2,4-O-二苄叉-D-山梨醇(DBS),收率91.2%;1,3∶2,4-O-二(4-甲基苄叉)-D-山梨醇(MDBS),收率90.5%;1,3∶2,4-O-二(3,4-二甲基苄叉)-D-山梨醇(DMDBS),收率89.0%。用原甲酸三甲酯作化学脱水剂,合成了1,3∶2,4-O-二(2,4,6-三甲基苄叉)-D-山梨醇(2,4,6-TMDBS),收率37.1%;1,3∶2,4-O-二(2,4,5-三甲基苄叉)-D-山梨醇(2,4,5-TMDBS),收率30.9%;1,3∶2,4-O-二(5,6,7,8-四氢萘-2-亚甲叉)-D-山梨醇(DTHNS),收率74.1%。其结构经1HNMR确认。测定了它们对21种有机溶剂的凝胶性能。发现苯环上取代基的位置、数量、大小等因素对凝胶性能有重要影响。2,4,6-TMDBS无凝胶性能,其余化合物对多种溶剂具有良好的凝胶性能,DTHNS对非极性化合物有极优良的凝胶性能。测试并比较了上述化合物的最低凝胶浓度,证实了凝胶-溶胶解缔温度随凝胶因子质量分数增加而增加;随着溶剂(一元直链伯醇)碳原子数的增加而增加。     

木糖醇缩醛类凝胶因子的合成及其凝胶性能的研究

以取代的苯甲醛和木糖醇为原料,环己烷为溶剂和夹带剂,甲醇为促进剂,十二烷基苯磺酸为催化剂,用共沸脱水法合成了5个木糖醇缩醛衍生物:1,3∶2,4-二(对甲基苄叉)-D-木糖醇(Ⅰ),1,3∶2,4-二(间甲基苄叉)-D-木糖醇(Ⅱ),1,3∶2,4-二(邻甲基苄叉)-D-木糖醇(Ⅲ),1,3∶2,4-二(3,4-二甲基苄叉)-D-木糖醇(Ⅳ),1,3∶2,4-二苄叉-D-木糖醇(Ⅴ)。将木糖醇缩醛衍生物用作低相对分子质量(以下简称分子量)有机凝胶因子,比较了其凝胶性能,取代基以空间位阻的形式影响凝胶因子分子的自组装,并能增强凝胶因子分子之间的相互作用。溶剂通过范德华力参与了凝胶三维网络的构建,提高网络的强度。红外光谱测试表明,凝胶形成过程中生成的氢键是该类凝胶因子自组装的驱动力。     

长链烷氧基芳香醇凝胶因子的合成及性能

为了研究有机凝胶的溶剂效应,合成了单链烷氧基芳香醇系列化合物S-C12、S-C14、S-C16及三链化合物T-C14。测试了它们的凝胶性能并分析了侧链的影响。阴离子测试结果表明,该系列凝胶化合物可以对氟离子刺激作出响应。运用扫描电子显微镜观察并分析了凝胶的微观形貌,并通过核磁共振光谱及红外光谱研究了系列化合物的成胶驱动力。红外光谱中,溶液状态下游离态羟基吸收波数(3 673 cm~(-1))较凝胶状态下(3 651cm~(-1))发生了蓝移,由此证明氢键是凝胶形成的重要驱动力。计算了凝胶因子S-C14及14种有机溶剂的梯氏参数并绘制了梯氏图,获得S-C14在有机溶剂中形成凝胶的预测区域,并对该预测区域的有效性进行了验证。采用Kamlet-Taft参数法分析并明确了溶剂得失氢键能力以及溶剂极性对所合成化合物凝胶性能的影响,并利用文献报道的系列凝胶因子对所得结论的一致性进行了验证。     

长碳链脲基氨基甲酸酯的合成及其凝胶性能研究

合成了一类新型的长碳链型脲基氨基甲酸酯低分子量有机凝胶因子,测试了它们对不同溶剂的凝胶性能.首先用脂肪醇与甲苯-2,4-二异氰酸酯反应生成相应的氨基甲酸酯;再与脂肪胺反应以较高的收率得到目标产物.产物结构均经过HINMR确认.实验结果表明此类凝胶因子具有非常好的凝胶性能.使用FT-IR发现氢键在此类凝胶因子形成有机凝胶...     

吡啶二酰胺类凝胶因子的合成及性能

合成了系列不同侧链的吡啶二酰胺类衍生物4a、4b、4c、5、9。测试并对比了其凝胶性能,结果表明该类化合物在有机溶剂中具有较好的凝胶性能且侧链对其性能具有很大影响。通过紫外光谱及红外光谱测试研究了系列化合物的成胶驱动力;阴离子测试结果表明该系列凝胶具有阴离子响应特性,同时验证了氢键作用的存在。运用扫描电子显微镜观察并分析了凝胶的微观形貌。计算了凝胶因子9和8种溶剂的梯氏参数,绘制了相应的梯氏参数图,并对预测成胶区域的有效性进行了验证。     

Effect of gelator structures on electrochemical properties of ionic-liquid supramolecular gel electrolytes

Bis(4-acylaminophenyl)methane (G1) and bis(4-acylaminophenyl)ether (G2) with varied acyl chains were found to be efficient gelators for the gelation of imidazole-based ionic liquids. The supramolecular gel electrolytes were formed via the self-assembly of these gelators in ionic liquids. The minimum gelator concentrations (MGCs) for the gelation of ionic liquids depend on the chemical structures of the gelators. The longer the acyl chains, the lower the MGCs. Polarized optical microscopy images of the ionic-liquid gels reveal the formation of spherical crystallites resulting from the fibrillar aggregates of the gelators. In addition, the phase transition temperatures of the ionic-liquid gels increase with an increase of the acyl chain length of the gelators. The impedance spectra of the ionic-liquid gels indicate that the temperature dependence of the conductivity follows the classical Arrhenius equation. The conductivities of ionic-liquid gels also decrease with an increase of the acyl chain length, but the differences in conductivities between the gels and corresponding ionic liquids are in one order of magnitude. The ionic-liquid gels possess a stable electrochemical window.     

溴代苝二酰亚胺衍生物的光谱及其在溶液中的聚集

设计合成了一种新型的苝二酰亚胺衍生物1,6,7,12-四溴代-N,N-丙酸2-(2-氨基乙氧基)乙醇酯苝四羧酸酐.研究了在不同有机溶剂中的紫外、荧光光谱性能以及相应的聚集行为.光谱研究表明,在4种不同的溶剂中,临界聚集浓度不同.随着溶液浓度的增加,化合物分子呈斜线发生面-面堆积.SEM观察了在有机溶液中的聚集形貌,受分...     

A heat transfer model and supporting experiments to guide the uniform gelation of molecular oleogels during scale-up

The quest for novel vegetable oil structuring strategies has been progressing since the discovery of the deleterious impacts of trans fats. Although oleogelation using bioderived molecular gelators has been proven to be successful as an alternative to traditional hydrogenation methods, efforts are needed to meet the industrial requirements. A major constraint during the fabrication of oleogels is to achieve consistency in physical properties during scale-up. Experiments showed that gelation fails to occur when larger volumes were prepared based on the minimum gelation concentration (MGC) of gelators, determined using the smallest oil volume (1 ml), a general laboratory practice. This observation was consistent with all the molecular gelators used in this study; sorbitol dioctanoate, mannitol dioctanoate, and 12-hydroxystearic acid. To understand this behavior, a mathematical model was developed since gelator network propagation is governed by the cooling rate. The model indicates that maintenance of a minimal thermal gradient via uniform heat dissipation and gelation time is necessary to achieve homogeneous gel propagation across the vial. With these predictions, we hypothesized and confirmed that oleogels with constant surface area-to-volume ratio could result in identical gelation times and consistent physical properties (MGC, melting temperature, melting enthalpy, yield stress, solid phase content, and oil binding capacity) during scale-up.     

Atomic force microscopic (AFM) study on a self-organizing polymer film

Summary The structure of a self-organized polymer film prepared by slow evaporation of organic solvents is studied by atomic force microscopy, and compared with that of polymer film prepared by natural evaporation of organic solvents. AFM studies clearly indicates that there exists a self-organizing process of alkyl chains resulting in the partial interdigitated layer structure under the condition of slow evaporation of organic solvents. Received: 27 July 1998/Revised version: 7 October 1998/Accepted: 2 November 1998     

Unique block molecules based on glycerol skeleton as C‐3 building blocks for liquid crystals formation by self‐assembly and their future potential for the “nano‐chemistry”

Studies on design of liquid crystalline block molecules with non‐conventional mesophase morphoplogies have been proposed by Tschierske and co‐workers. These block molecules have a rigid core, a lateral substituent, and an alkyl chain segmenting blocks from each other. Related to this, diglyceryl alkyl ethers found by us have glycerol as a rigid core, a lateral substituent, and an alkyl chain similar to the Tschierske design. These two cases are compared with each other with regard to the relationship between the molecular structure and the liquid crystalline morphologies and other properties. Recently, new soft materials suitable for liquid crystals exhibiting self‐assembly of phase‐segregated structures have been designed. Typical examples of such “block” molecules containing glycerol having a C‐3 building block include: (i) undecyl‐glycerylether‐ modified siloxane derivatives with a siloxane segment as the rigid core and alkyl chains with 2, 3‐dihydroxypropoxy group as a hydrophilic group at a lateral or terminal position of the siloxane segment; (ii) novel hyper branched dendrimers forming the basis of polyglycerol nanocapsules with a core‐shell molecular architecture; (iii) carbon nanotubes based on cyclodextrins (CDs); (iv) polymerizable amphiphilic diacetylene‐containing phospholipids suitable for construction of functional nanocomposites. This is done by self‐assembly and polymerization of diacetylene creating a “block molecular structure” with a polyacetylene chain as a rigid core segment, the lipid headgroups as the hydrophilic segment, and terminal flexible alkyl chains. On the basis of these results, future potential of block molecules as a soft building material for liquid crystalline structures was discussed.     

Supramolecular Phase-Selective Gelation by Peptides Bearing Side-Chain Azobenzenes: Effect of Ultrasound and Potential for Dye Removal and Oil Spill Remediation

Phase selective gelation (PSG) of organic phases from their non-miscible mixtures with water was achieved using tetrapeptides bearing a side-chain azobenzene moiety. The presence of the chromophore allowed PSG at the same concentration as the minimum gelation concentration (MGC) necessary to obtain the gels in pure organic phases. Remarkably, the presence of the water phase during PSG did not impact the thermal, mechanical, and morphological properties of the corresponding organogels. In the case of miscible oil/water mixtures, the entire mixture was gelled, resulting in the formation of quasi-hydrogels. Importantly, PSG could be triggered at room temperature by ultrasound treatment of the mixture or by adding ultrasound-aided concentrated solution of the peptide in an oil-phase to a mixture of the same oil and water. Moreover, the PSG was not affected by the presence of salts or impurities existing in water from natural sources. The process could be scaled-up, and the oil phases (e.g., aromatic solvents, gasoline, diesel fuel) recovered almost quantitatively after a simple distillation process, which also allowed the recovery and reuse of the gelator. Finally, these peptidic gelators could be used to quantitatively remove toxic dyes from aqueous solutions.     

Organogel Formation of Soybean Oil with Waxes

Many waxes including plant waxes and animal waxes were evaluated for the gelation ability toward soybean oil (SBO) and compared with hydrogenated vegetable oils, petroleum waxes and commercial non-edible gelling agents to understand factors affecting the gelation ability of a gelator. Sunflower wax (SW) showed the most promising results and all SW samples from three different suppliers could make a gel with concentrations as low as 0.5 wt%. Candelilla wax and rice bran wax also showed good gelation properties, which, however, varied with different suppliers. Gelation ability of a wax is significantly dependant on its purity and detailed composition. A wax ester with longer alkyl chains has significantly better gelation ability toward SBO than that with shorter alkyl chains indicating that the chain length of a component in a wax such as wax ester is an important factor for gelation ability. The SW–SBO organogel showed increased melting point with increased SW content, showing the melting point range from about 47 to 65 °C with 0.5–10 wt% SW. The effects of cooling rate on crystal size and firmness of a gel were investigated. The dependence of firmness on cooling rate was so significant that the desired texture of an organogel could be achieved by controlling the cooling rate in addition to controlling the amount of gelling agent. This research reveals that a small amount of food grade plant waxes including SW may replace a large amount of the hardstock containing trans-fat or saturated fat.     

含吡啶小分子胶凝剂研究进展

简述了含吡啶结构的小分子胶凝剂的研究进展，介绍了这类胶凝剂的结构特点、胶凝行为和凝胶性能。     

Molecular organogels. Soft matter comprised of low-molecular-mass organic gelators and organic liquids

This Account presents recent advances in understanding how and why dilute solutions/sols of low-molecular-mass organic gelators (LMOGs) undergo microscopic phase separation to form self-assembled fibrillar networks in molecular organogels. Concepts are illustrated structurally at the subnanometer (molecular) to several millimeter (bulk) length scales and dynamically over time scales that follow the assembly of supersaturated solutions/sols into gel phases. Examples include both structurally complicated (ALSmolecules with aromatic, linking, and steroidal groups) and simple (n-alkanes or n-alkanes along whose chains a hetero-group has been inserted) LMOGs in a wide range of organic liquids.     

Sulfonated polyisobutylene telechelic ionomers. XIII. Viscosity behavior in nonpolar solvents and nonpolar–polar solvent mixtures

The effect of molecular variables upon the dilute solution viscosity of sulfonated polyisobutylene telechelic ionomers has been studied in both nonpolar solvents and nonpolar–polar solvent mixtures. In nonpolar solvents, association of the terminal salt groups results in an increase in viscosity and gelation at very low concentrations. The concentration at which gelation occurs was found to be dependent upon molecular variables such as architecture, molecular weight, neutralizing cation, extent of neutralization, and the type of solvent. Addition of a small amount of a more polar cosolvent tends to break up ionic associations between polymer chains and thus reduces viscosity. Finally, such solutions with a small amount of polar cosolvent may display dramatic increases in viscosity with increasing temperature due to a dynamic equilibrium between the ionic groups on the polymer chain, the nonpolar solvent, and the polar cosolvent. The results of this work suggest that these ionomers may potentially be useful as viscosity modifiers or “thermal thickeners” in some applications.