New Acyclic Dimers of Cholic Acid with Oxamide and Hydrazide Spacers

Summary. Three new acyclic dimers of cholic acid with oxamide and isomeric hydrazide (N,N′-diacylhydrazine) spacers were obtained. The oxamide spacers bind two identical steroidal subunits through position 3 (head-to-head dimer) or position 23 (tail-to-tail dimer). In the case of a third dimer the hydrazine moiety binds two molecules of cholic acid through position 24 (tail-to-tail dimer).     

Dimeric Cholaphanes with Oxamide Spacers

Two new dimeric cholaphanes with oxamide spacers were prepared. The spacers bind two identical steroidal subunits through positions 3,3′ and 24,24′ (head-to-head dimer) or positions 3,24′ and 3′,24 (head-to-tail dimer).     

基于氢键作用由低分子量凝胶因子形成的超分子水凝胶

利用对羟基吡啶及均苯四甲酸合成的超分子单体, 基于分子间氢键作用, 在水中成功地制备出了具有温度响应性的超分子凝胶, 研究了制备条件对凝胶结构的影响.     

New Acyclic Dimers of Cholic Acid with Oxamide and Hydrazide Spacers

Three new acyclic dimers of cholic acid with oxamide and isomeric hydrazide (N,N′-diacylhydrazine) spacers were obtained. The oxamide spacers bind two identical steroidal subunits through position 3 (head-to-head dimer) or position 23 (tail-to-tail dimer). In the case of a third dimer the hydrazine moiety binds two molecules of cholic acid through position 24 (tail-to-tail dimer).     

New Cyclic Dimers of Cholic Acid

Summary. Two new cyclic dimers of cholic acid were obtained in the reaction of 3-O-acetyl methyl cholate with oxalyl chloride. The oxalates bound the cholate subunits side-to-side as a result of acylation of 7 and 12 OH groups in the substrate. The selective deprotection of hydroxy groups at C-3 and C-24 proved to be rather difficult and led to various products depending on the reaction conditions.     

Mechanism of N-octadecyl-N'-maleoyl-L-phenylalanine self-assembled into supramolecular structures

N-Octadecyl-N'-maleoyl-L-phenylalanine (ODMA-L-Phe) was synthesized through the condensation, deprotection and aeid-ylation reaction of BOC-L-phenylalanine, octadecylamine and maleic anhydride. ODMA-L-Phe can self-assemble in some organic solvents and turned them into thermally reversible physical supramolecular organogels. The morphology of ODMA-L-Phe aggregates was characterized by polarized optical microscopy (POM) and field emission scanning electron microscope (FE-SEM). The aggregates of ODMA-L-Phe were needle-like fibrils with diameters of approximately 100-200 nm. The mechanism of ODMA-L-Phe self-assembly in organic solvents was investigated using 1H NMR and circular dichroism (CD). The results indicated that hydrogen bonding was one of the main driving forces for the self-assembly of ODMA-L-Phe.     

Mechanism of N-octadecyl-N′-maleoyl-L-phenylalanine self-assembled into supramolecular structures

N-Octadecyl-N′-maleoyl-L-phenylalanine(ODMA-L-Phe)was synthesized through the condensation,deprotection and acid- ylation reaction of BOC-L-phenylalauine,octadecylamine and maleic anhydride,ODMA-L-Phe can self-assemble in some organic solvents and turned them into thermally reversible physical supramolecular organogels.The morphology of ODMA-L-Phe aggregates was characterized by polarized optical microscopy(POM)and field emission scanning electron microscope(FE-SEM). The aggregates of ODMA-L-Phe were needle-like fibrils with diameters of approximately 100-200 nm.The mechanism of ODMA- L-Phe serf-assembly in organic solvents was investigated using ~1H NMR and circular dichroism(CD).The results indicated that hydrogen bonding was one of the main driving forces for the self-assembly of ODMA-L-Phe.     

Mechanism of N-octadecyl-N1-maleoyl-L-phenylalanine self-assembled into supramolecular structures

N-Octadecyl-N1-maleoyl-L-phenylalanine （ODMA-L-Phe） was synthesized through the condensation, deprotection and acid- ylation reaction of BOC-L-phenylalanine, octadecylamine and maleic anhydride. ODMA-L-Phe can self-assemble in some organic solvents and turned them into thermally reversible physical supramolecular organogels. The morphology of ODMA-L-Phe aggregates was characterized by polarized optical microscopy （POM） and field emission scanning electron microscope （FE-SEM）. The aggregates of ODMA-L-Phe were needle-like fibrils with diameters of approximately 100-200 nm. The mechanism of ODMA- L-Phe self-assembly in organic solvents was investigated using XH NMR and circular dichroism （CD）. The results indicated that hydrogen bonding was one of the main driving forces for the self-assembly of ODMA-L-Phe.     

Highly stable supramolecular hydrogels formed from 1,3,5-benzenetricarboxylic acid and hydroxyl pyridines

New supramolecular hydrogels with the maximal sol-gel transition temperature(T_(gel)) of 95℃were obtained by using gelators formed from 1,3,5-benzenetricarboxylic acid(BTA) and para-hydroxyl pyridine(PHP) or meta-hydroxyl pyridine(MHP).The single crystal structure of the complex formed from BTA and ortho-hydroxyl pyridine(OHP) indicated that the molecules assembled into superstructure via both hydrogen bonds andπ-πstacking interaction.     

Design,preparation and applications of gel nanocomposites from bile acids – A brief review

Synthesis of advanced hybrid materials formed by the unification of nanoparticles with gels is gaining importance due to their unusual properties coupled with the ease of fabrication. The gel medium provides a template for generating complex inorganic nanostructures with controlled size and desirable mechanical properties. In this paper, we review the synthesis of various inorganic nanoparticles in gel matrices formed by the self-assembly of bile acid-derived gelators and the role of the gel medium to improve the properties of the nanocomposites.     

Supramolecular conducting microfibers from amphiphilic tetrathiafulvalene-based organogelator

An amphiphilic tetrathiafulvalene molecule can gelate a variety of organic solvents in view of multiple intermolecular interactions, especially in polar solvent with the formation of highly-ordered columnar structures. The formation of mixed-valence states shows the semiconductive behaviors with the conductivity of 10^-4 S/cm, as promising candidates for organic electronics.     

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.     

Enantioselective binding of amino acids and amino alcohols by self-assembled chiral basket-shaped receptors

Amino acid appended diphenylglycoluril-based chiral molecular receptors 2 and 3 have been prepared and their aggregation has been studied in water at various pH's and in chloroform. The binding of several biologically relevant guests with aromatic moieties to these aggregates has been studied with UV-Vis spectroscopy in competition experiments with 4-(4-nitrophenylazo)resorcinol (Magneson) and 2-(4-hydroxyphenylazo)benzoic acid (HABA) as probes. Aggregates of chiral host 2b showed binding of catecholamines and aromatic amino acids in an aqueous environment, as well as discrimination between amino acid enantiomers, and can be considered a mimic for adrenergic receptors.     

Ultrasound induced formation of organogel from a glutamic dendron

New l-glutamic acid based dendritic compounds: N-(2-naphthacarbonyl)-l-glutamic acid diethyl ester (NGE) and N-(2-naphthacarbonyl)-1,5-bis(l-glutamic acid diethyl ester)-l-glutamic diamide (NBGE) were designed. Although NGE could not form any gels in common solvents, NBGE could form stable gels in hexane, toluene, and water under ultrasound. Three dimensional network structures composed of fibers with various diameters were observed in the gel by SEM and TEM. FTIR spectral measurement revealed that ultrasound during cooling of the solution could destroy some of the hydrogen bond interactions and caused the gel formation. In solution, no CD signal was detected because the naphthyl chromophore is far from the chiral center. In the gel, however, CD signals assigned to the naphthyl group were observed, which indicated that the chirality of the chiral center could be transferred to the chromophore in the supramolecular organogel system.     

Molecular-scale drug delivery systems loaded with oxaliplatin for supramolecular chemotherapy

Smart strategies that can decrease the side effect and enhance the therapeutic efficacy of chemotherapy are in urgent need to meet the special demands of cance r therapy.Herein,two wate r-soluble macrocyclic hosts,i.e.,a carboxylated leaning tower[6]arene(CLT6) and a carboxylated [2]biphenyl-extended pillar[6]arene(CBpP6),are used to load chemotherapy drug oxaliplatin(OxPt) by forming inclusion complexes(OxPt■CLT6 and OxPt■CBpP6) through host-guest interactions.Interestingly,OxPt can be released from the macrocyclic cavities of these drug delivery systems(DDSs) via the competitive binding effect of spermine(SPM) because of the stronger binding abilities of CLT6/CBpP6 toward SPM as compared with OxPt,leading to enhanced cytotoxicity on SPM-overexpressed cancer cells,such as breast cancer MCF-7 cells.Moreover,compared to free OxPt,due to the low concentration of SPM in normal cells,OxPt■CGT6 and OxPt■CBpP6 demonstrated a decreased cytotoxicity on liver L02 cells,which is beneficial fo r reducing the side effect of anticancer drug during chemotherapy.Such a strategy might be extended to other antitumor drugs and water-soluble macrocycles with suitable cavity sizes to achieve controllable drug delivery and enhanced anticancer ability in supramolecular chemotherapy     

β-Homoalanyl PNAs: Synthesis and Indication of Higher Ordered Structures

Self-pairing complexes with extraordinarily high stability are formed by β-PNAs with four to six units of the nucleo-β-amino acid 1 . The key step in the synthesis is a Mitsunobu reaction between a β-homoserine and a purine derivative.     

Enantioselective Extraction of Dinitrophenyl Amino Acids Mediated by Lipophilic Deoxyguanosine Derivatives: Chiral Discrimination by Self-Assembly

The transfer of potassium salts of dinitrophenyl amino acids from water to chloroform by the lipophilic guanosine derivative 1 takes place enantioselectively. Depending on the K⁺: 1 ratio, G-quartets of 1 self-assemble into octamers ( O ) or polymers.     

Design,synthesis and application of new bile acid ligands with 1,2,3-triazole ring

New dimers have been obtained from propargyl ester of bile acids and α,α′-diazide-m-xylene by intermolecular 1,3-dipolar cycloaddition. These compounds have been used as ligands to form intermolecular hydrogen bonds with various aromatic acids. The structures of all products were confirmed by spectroscopic (¹H NMR, ¹³C NMR and FT-IR) analysis, mass spectrometry (ESI, MALDI) and PM5 semiempirical methods.     

Dinuclear Tin(II) Complex of a Bulky cis‐Oxamide: Synthesis,Characterization, Crystal Structure,and DFT Studies

The reaction of the di‐lithiated oxamide of 1 with two equivalents of SnCl₂ provided the tin trans‐oxamide 3 . In solution, spectroscopic analysis suggests exclusively the formation of a trans‐oxamide (trans‐ 3 ). However, the solid state shows an atypical cis‐oxamide (cis‐ 3 ), where the oxamide fragment acts as an anti‐Janus head ligand. An ¹¹⁹Sn‐NMR variable temperature experiment ([D₈]THF) of the trans‐oxamide (trans‐ 3 ) was performed however, at lower temperature no additional signal was observed, which confirmed the absence of a dynamic equilibrium. Dispersion‐corrected density functional calculations revealed that the cis conformation of this tin(II) oxamide complex is more stable than the trans isomer by 1.4 kcal · mol^–1.     

Amino acid binding in water by a new guanidiniocarbonyl pyrrole dication: the effect of the experimental conditions on complex stability and stoichiometry

The synthesis and binding properties of a new guanidiniocarbonyl pyrrole dication 2 are reported, which efficiently binds alanine carboxylate with log K_ass = 3.9 in buffered water. Due to the increased charge density in this dication, the binding constant is five times larger than for the parent guanidiniocarbonyl pyrrole monocation 1 (log K = 3.2). However, the experimental conditions for determining the binding constant significantly influence both complex stability and stoichiometry. With increasing amount of substrate added during the titration, the overall complex stability decreases due to the increasing ionic strength of the solution. Furthermore, the formation of 1:2 complexes between 2 and 7 becomes increasingly important. Therefore, for the comparison of binding data it has to be assured that exactly the same experimental conditions are used for their determination.