Visual-size molecular recognition based on gels

Additive-assisted macroscopic self-assembly and control of the shape of assemblies based on host-guest interaction

In these decades, considerable attention has focused on supramolecular polymers due to their unique structures and properties. More recently, macroscopic supramolecular polymers have attracted increasing interest from not only biologists but also materials scientists inspired by the sophisticated structures and functions of living organisms. Since the functions of supramolecular polymers are strongly dependent on their shape, control of the shape is an important issue in controlling the functions of supramolecular polymers. However, the control of shape in macroscopic supramolecular assemblies has not yet been sufficiently investigated. Previously, we studied the macroscopic self-assembly behavior of super absorbent polymer (SAP) microparticles modified with β-cyclodextrin (βCD) and adamantane (Ad) residues (βCD(x)-SAP and Ad(y)-SAP microparticles, where x and y are the mol% contents of βCD and Ad residues, respectively). More elongated assemblies were formed at higher y, indicating that the shape of assemblies can be controlled by varying the interaction strength. The noteworthy is that 1-adamantanamine hydrochloride (AdNH3Cl) assisted the formation of assemblies from βCD(x)-SAP and Ad(y)-SAP microparticles, indicating that AdNH3Cl acts as a chemical stimulus for macroscopic assemblies of βCD(x)-SAP and Ad(y)-SAP microparticles. In this study, we have thus studied the assembling behavior of βCD(x)-SAP microparticles with Ad(y)-SAP microparticles and unmodified SAP microparticles assisted by AdNH3Cl, as well as the shape of the resulting macroscopic assemblies. AdNH3Cl assisted the formation of assemblies from βCD(16.2)-SAP and Ad(15.1)-SAP microparticles, in which AdNH3Cl crosslinked the SAP microparticles through the formation of inclusion complexes of βCD residues with the Ad residue and the electrostatic interaction of ammonium and carboxylate residues. Assemblies of βCD(26.7)-SAP and unmodified SAP microparticles were formed at the concentrations of AdNH3Cl ([AdNH3Cl]0) higher than a certain level (ca. 0.05 mM). The aspect ratio (a/b) of assemblies showed a maximum at [AdNH3Cl]0 ~ 0.10 mM, indicating that the chemical stimulus, i.e., addition of AdNH3Cl, controls the shape of assemblies formed from βCD(26.7)-SAP and unmodified SAP microparticles. This study suggests that other stimuli, e.g., heat, pH, light, redox, and force, can be utilized to control the shape of macroscopic assemblies based on supramolecular interactions.

An Encyclopedic Compendium on Chemosensing Supramolecular Metal-Organic Gels

Chemosensing, an interdisciplinary scientific domain, plays a pivotal role ranging from environmental monitoring to healthcare diagnostics and (inter)national security. Metal-organic gels (MOGs) are recognized for their stability, selectivity, and responsiveness, making them valuable for chemosensing applications. Researchers have explored the development of MOGs based on different metal ions and ligands, allowing for tailored properties and sensitivities, and have even demonstrated their applications as portable sensors such as paper-based test strips for practical use. Herein, several studies related to MOGs development and their applications in the chemosensing field via UV-visible or luminance along with electrochemical approach are presented. These papers explored MOGs as versatile materials with their use in sensing bio or environmental analytes. This review provides a foundational understanding of key concepts, methodologies, and recent advancements in this field, fostering the scientific community.

Recent Advances in Stimuli-Responsive Metallogels

Recently, stimuli-responsive supramolecular gels have received significant attention because their properties can be modulated through external stimuli such as heat, light, electricity, magnetic fields, mechanical stress, pH, ions, chemicals and enzymes. Among these gels, stimuli-responsive supramolecular metallogels have shown promising applications in material science because of their fascinating redox, optical, electronic and magnetic properties. In this review, research progress on stimuli-responsive supramolecular metallogels in recent years is systematically summarized. According to external stimulus sources, stimuli-responsive supramolecular metallogels, including chemical, physical and multiple stimuli-responsive metallogels, are discussed separately. Moreover, challenges, suggestions and opportunities regarding the development of novel stimuli-responsive metallogels are presented. We believe the knowledge and inspiration gained from this review will deepen the current understanding of stimuli-responsive smart metallogels and encourage more scientists to provide valuable contributions to this topic in the coming decades.

Current state of knowledge on intelligent-response biological and other macromolecular hydrogels in biomedical engineering: A review

Because intelligent hydrogels have good biocompatibility, a rapid response, and good degradability as well as a stimulus response mode that is rich, hydrophilic, and similar to the softness and elasticity of living tissue, they have received widespread attention and are widely used in biomedical engineering. In this article, we conduct a systematic review of the use of smart hydrogels in biomedical engineering. First, we introduce the properties and applications of hydrogels and compare the similarities and differences between traditional hydrogels and smart hydrogels. Secondly, we summarize the intelligent hydrogel types, the mechanisms of action used by different hydrogels, and the materials for preparing different types of hydrogels, such as the materials for the preparation of temperature-responsive hydrogels, which mainly include gelatin, carrageenan, agarose, amylose, etc.; summarize the morphologies of different hydrogels, such as films, fibers and microspheres; and summarize the application of smart hydrogels in biomedical engineering, such as for the delivery of proteins, antibiotics, deoxyribonucleic acid, etc. Finally, we summarize the shortcomings of current research and present future prospects for smart hydrogels. The purpose of this paper is to provide researchers engaged in related fields with a systematic review of the application of intelligent hydrogels in biomedical engineering. We hope that they will get some inspiration from this work to provide new directions for the development of related fields.

Construction and Ion Transport-Related Applications of the Hydrogel-Based Membrane with 3D Nanochannels

Hydrogel is a type of crosslinked three-dimensional polymer network structure gel. It can swell and hold a large amount of water but does not dissolve. It is an excellent membrane material for ion transportation. As transport channels, the chemical structure of hydrogel can be regulated by molecular design, and its three-dimensional structure can be controlled according to the degree of crosslinking. In this review, our prime focus has been on ion transport-related applications based on hydrogel materials. We have briefly elaborated the origin and source of hydrogel materials and summarized the crosslinking mechanisms involved in matrix network construction and the different spatial network structures. Hydrogel structure and the remarkable performance features such as microporosity, ion carrying capability, water holding capacity, and responsiveness to stimuli such as pH, light, temperature, electricity, and magnetic field are discussed. Moreover, emphasis has been made on the application of hydrogels in water purification, energy storage, sensing, and salinity gradient energy conversion. Finally, the prospects and challenges related to hydrogel fabrication and applications are summarized.

Instantaneous High-Resolution Visual Imaging of Latent Fingerprints in Water Using Color-Tunable AIE Pincer Complexes

Instant visualization of latent fingerprints is developed by using a series of water-soluble terpyridine zinc complexes as aggregation-induced emission probes in pure water, under UV light or ambient sunlight. By simply soaking, or spraying with an aqueous solution of the probe, bright yellow fluorescence images with high contrast and resolution are readily developed on various surfaces including tinfoil, glass, paper, steel, leather, and ceramic tile. Remarkably, latent fingerprints can be visualized within seconds including details of whorl and sweat pores. The color of emission can be tuned from blue to orange by modifying the pincer ligands, allowing direct imaging under sunlight. These inexpensive, water-resistant, and color-tunable probes provide a practical approach for latent fingerprints recording and analysis, security protection, as well as criminal investigation in different scenarios.

Functional supramolecular gels based on poly(benzyl ether) dendrons and dendrimers

Supramolecular gels, as a fascinating and useful class of soft materials, constructed from low-molecular-weight gelators via noncovalent interactions have attracted increasing attention in the past few decades. Dendrimers and dendrons are highly branched and monodisperse macromolecules with a well-defined three-dimensional architecture and multiple surface functionalities. In recent years, poly(benzyl ether) dendrimers and dendrons are found to be powerful candidates for constructing gel phase materials in organic or aqueous media due to the advantages of capability of forming multiple noncovalent interactions and significant steric impact. In this Feature Article, we provide a comprehensive overview of recent progress in supramolecular gels involving poly(benzyl ether) dendritic molecules. Firstly, we outline the molecular design strategies of dendritic gelators with an emphasis on the discussion of their gelating units and position in molecular structures. Subsequently, we discuss the potential applications of dendritic gels in light harvesting, stimuli responsive materials, sensors and environmental remediation. In addition, the potential challenges and future perspectives of poly(benzyl ether) dendritic gels have also been discussed. It is hoped that this feature article will attract increasing attention and provide some valuable insights for the future design and evolution of supramolecular gels.

Chiral gelators for visual enantiomeric recognition

Introduction of chirality in supramolecular gels has allowed the effective translation and amplification of molecular chirality. Upon integrating the stimuli-responsive nature of these gels with supramolecular chirality, a new platform for the discrimination of the enantiomeric guests through naked eye can be developed. Over the past decade, several groups have reported the development of chiral supramolecular gels for enantioselective recognition through gel formation or collapse. However, to the best of our knowledge, we are yet to come across a review highlighting the utilization of chiral supramolecular gels for macroscopic discrimination of enantiomers. In this article, we have articulated the chiral gelators developed to date for the recognition of different enantiomeric analytes focusing on their mode of recognition with an in-depth analysis of the mechanism of interactions assisting the recognition process.

Stimuli responsive dynamic transformations in supramolecular gels

Supramolecular gels are formed by the self-assembly of small molecules under the influence of various non-covalent interactions. As the interactions are individually weak and reversible, it is possible to perturb the gels easily, which in turn enables fine tuning of their properties. Synthetic supramolecular gels are kinetically trapped and usually do not show time variable changes in material properties after formation. However, such materials potentially become switchable when exposed to external stimuli like temperature, pH, light, enzyme, redox, and chemical analytes resulting in reconfiguration of gel matrix into a different type of network. Such transformations allow gel-to-gel transitions while the changes in the molecular aggregation result in alteration of physical and chemical properties of the gel with time. Here, we discuss various methods that have been used to achieve gel-to-gel transitions by modifying a pre-formed gel material through external perturbation. We also describe methods that allow time-dependent autonomous switching of gels into different networks enabling synthesis of next generation functional materials. Dynamic modification of gels allows construction of an array of supramolecular gels with various properties from a single material which eventually extend the limit of applications of the gels. In some cases, gel-to-gel transitions lead to materials that cannot be accessed directly. Finally, we point out the necessity and possibility of further exploration of the field.

A naphthalimide-linked new pyridylazo phenol derivative for selective sensing of cyanide ions (CN-) in sol-gel medium

Napthalimide-linked pyridylazo derivatives 1 and 2 have been designed and synthesized. Compound 1 acts as a gelator in DMF-H₂O (1 : 1, v/v). The brown gel is photostable and shows good viscoelastic properties. The value of G' is almost 10 times higher than that of G'' over the entire range of frequencies at a constant strain of 1%. The SEM image shows the presence of densely stacked flakes. In comparison, compound 2, devoid of free phenolic -OH, does not show gelation properties under identical conditions. However, the brown gel of 1 shows selective sensing of CN^- ions over a series of anions involving phase change through the deprotonation mechanism. While the brown gel of 1 is selectively ruptured in the presence of CN^- to the sol, compound 1 in solution shows measurable UV-vis and emission changes in the presence of CN^- over the other anions and validates the visual sensing of CN^-. In the test-kit application, the yellow paper strip turned into pinkish-red upon contact with CN^-.

Stimuli-responsive behavior of naphthyl acylhydrazone derivative and its application in information security protection

Acylhydrazone derivatives containing naphthyl group, namely, 3,5-bis-octyloxy-benzoic acid naphthalen-1-ylmethylene-hydrazide (NTH-mB8) and 4-methoxy-benzoic acid naphthalen-1-ylmethylene-hydrazide (NTH-P1) were synthesized. π-π interactions between naphthalene groups and -N-H···O=C- intermolecular hydrogen bondings were observed in NTH-P1 single crystal, in which -C=N- bonds exhibited trans-isomer. NTH-mB8 showed photo-responsive behavior due to photo-induced trans-cis isomerizations of -C=N- bonds. Interestingly, the NTH-mB8 films fumed by trifluoroacetic acid (TFA)/triethylamine (TEA) (or standing at room temperature) vapors show reversible fluorescence on/off switching property. The cast film of NTH-mB8 exhibited almost no fluorescence. The NTH-mB8 film fumed by TFA vapor exhibited intensive cyan emission, which was quickly quenched by TEA vapor. The reversible remarkable fluorescence on/off switching properties suggested that the organic solution of NTH-mB8 could be used as security ink without needing a covering reagent in information security protection.

Reversible Chromatic Change of Supramolecular Gels for Visual and Selective Chiral Recognition of Histidine

In the present work, a chemical reaction has been performed for supramolecular gels to achieve multiple-stimuli-responsive smart soft materials. Simple chiral binaphthalene-based receptors can condense with histidine (His) to yield a Schiff base, which would help to achieve visual chiral recognition of unprotected l/d-His through gel formation along with specific selectivity toward 20 amino acids. Through intermolecular hydrogen bonds, the resultant Schiff base molecules assemble with excess His molecules to form three-dimensional (3D) networks of metastable cross-linked nanospheres and stable nanofibers in EtOH/water and MeOH/water, respectively. Significantly, this condensation reaction exhibits unique reversible and chromatic phenomena between sol-gel phase transitions in EtOH/water, which provide a way to design chemical reaction-based multivisual-change supramolecular gels for sensing and switching applications.

Ultralow-Molecular-Weight Stimuli-Responsive and Multifunctional Supramolecular Gels Based on Monomers and Trimers of Hydrazides

The simpler, the better. A series of simple, neutral and ultralow-molecular-weight (MW: 140-200) hydrazide-derived supramolecular gelators have been designed and synthesized in two straightforward steps. For non-conjugated cyclohexane-derived hydrazides, their monomers can self-assemble to form gels through intermolecular hydrogen bonds and dipole-dipole interactions. Significantly, conjugated phthalhydrazide can self-aggregate into planar and circular trimers through intermolecular hydrogen bonds and then self-assemble to form gels through intermolecular π-π stacking interactions. It is interesting that these simple gelators exhibit unusual properties, such as self-healing, multi-response fluorescence, and visual and selective recognition of chiral (R)/(S)-1,1'-binaphthalene-2,2'-diamine and S^2- through much different times of gel re-formation and blue-green color change, respectively. These results underline the importance of supramolecular gels and extend the scope of supramolecular gelators.

Supramolecular organogel formation through three-dimensional α-cyclodextrin nanostructures: solvent chirality-selective organogel formation

Novel supramolecular organogels were efficiently formed by mixing a 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) solution of α-cyclodextrin (α-CD) with 1- or 2-butanol via the formation of three-dimensional hexagonal nanostructures composed of head-to-tail α-CD channel assemblies. Mixing (R)- and (S)-2-butanol with an α-CD/HFIP solution realized (S)-2-butanol-selective organogel formation.

Visible Enantiomer Discrimination via Diphenylalanine-Based Chiral Supramolecular Self-Assembly on Multiple Platforms

The development of enantioselective recognition is of great significance in medical science and pharmaceutical industry, which associates with the molecular recognition phenomenon widely observed in biological systems. In particular, the facile and straight achievement of visual enantioselective recognition has been drawing increasing consideration, but it is still a challenge. Herein, a heterochiral diphenylalanine-based gelator (LFDF) is synthesized, presenting left-handed nanofibers during self-assembly in ethanol, which accomplishes the phenylalaninol enantiomer recognition on multiple platforms. When adding l- or d-phenylalaninol into LFDF supramolecular solution followed by ultrasonic treatment, precipitate and gel are formed, respectively. Meanwhile, LFDF supramolecular gel completely collapses in a minute after dropping l-phenylalaninol, while the gel almost remains when d-type is employed. Moreover, a fluorescent supramolecular xerogel (ThT-LFDF) is fabricated by combining the LFDF gelator with thioflavine T (ThT), which could detect l-phenylalaninol accompanying with fluorescence quenching while d-type with barely decreasing. And the ThT-LFDF xerogel system shows a good sensitivity (reaches to ppm) for the detection of l-phenylalaninol. It is found that the chirality of the assembled nanofibers, as well as amino and carboxyl of phenylalaninol, plays a critical role on the discrimination process. The multiple and visible enantioselective recognition of phenylalaninol through chiral supramolecular self-assemblies shows potential applications in the fields of medical science and pharmaceutical industry.

Environmentally responsive hydrogels for repair of cardiovascular tissue

Cardiovascular diseases (CVDs) pose a serious threat to human health, which are characterized by high disability and mortality rate globally such as myocardial infarction (MI), atherosclerosis, and heart failure. Although stem cells transplantation and growth factors therapy are promising, their low survival rate and loss at the site of injury are major obstacles to this therapy. Recently, the development of hydrogel scaffold materials provides a new way to solve this problem, which have shown the potential to treat CVD. Among these scaffold materials, environmentally responsive hydrogels have great prospects in repairing the microenvironment of cardiovascular tissues and vascular regeneration. They provide a new method for the treatment of cardiovascular tissue repair and space-time control for the release of various therapeutic drugs, including small-molecule drugs, growth factors, and stem cells. Herein, this article reviews the occurrence and current treatment of CVD, as well as the repair of cardiovascular injury by several environmental responsive hydrogels systems currently used, mainly focusing on the delivery of growth factors or the application of cell therapy to revascularization. In addition, we will also discuss the enormous potential and personal perspectives of environmentally responsive hydrogels in cardiovascular repair.

Chirality Transfer in Coassembled Organogels Enabling Wide-Range Naked-Eye Enantiodifferentiation

Enantiodifferentiation is crucial in organic chemistry, pharmacochemistry, material chemistry, and life science. However, it remains tremendously challenging to achieve a broad enantioselectivity to different types of chiral substrates via a single-material design. Here, we report a coassembled organogel strategy with chirality transfer to make an enantioselective generality possible. This coassembly contains two components: a chiral rigid molecular linker and an achiral block copolymer. Different from routine helically packed chiral self-assemblies, chirality transfer from the linker to the copolymer directed the coassembly to form a phase-segregated twisted nanofiber, in cooperation with H-bonding and microphase segregation. An organogel was accordingly formed by the further cross-linking in ethanol, where the rigid chiral linker served as the scaffold. On this basis, the system becomes highly sensitive, enabling a naked-eye sensing toward the single enantiomer of a diverse series of chiral species (including axial, point, planar, and polymeric chirality) via gel-to-micelle transformation, due to the asymmetric interaction hampering the chirality transfer in the coassembly and destroying the hierarchical structure. Such a strategy, based on a significant amplification of the stereoselective interactions, facilitates a simple and straightforward way to distinguish a broad optical activity independent of devices.

A colorimetric and fluorescent sensor for the detection of both fluoride ions and trifluoroacetic acid based on acylhydrazone derivatives

An acylhydrazone-based colorimetric and fluorescent sensor (PAH-8) for the detection of fluoride ions (F-) and trifluoroacetic acid (TFA)/triethylamine (TEA) has been studied. PAH-8 solution and organogel are highly selective and sensitive to F- among various tested anions (F-, Cl-, Br-, AcO-, and H2PO4-) in DMSO. Upon addition of F-, the maximum absorption wavelength of PAH-8 in DMSO solution shows a big red shift from 377 nm to 464 nm with a marked color change from colorless to yellow, and the fluorescence emission also displays a red shift from 438 nm to 532 nm with its fluorescence emission switching from blue to yellow. Both Job's plot and the Benesi-Hildebrand plot confirm a 1 : 1 stoichiometric relationship between PAH-8 and F-. The detection limit of PAH-8 for the analysis of F- can reach 8.31 × 10-7 M. Very interestingly, an expeditious 'naked eye' detection of F- can be realized by the reversible gel-sol transition, along with a color change from slight yellow to bright red and fluorescence quenching. In addition, the cast film of PAH-8 (the solution was developed from the DMSO gel upon the addition of TBAF) can detect water in air by color switching or fluorescence on/off. In both solution and solid states, PAH-8 also exhibits obvious acid-base stimulated fluorescence conversion. The solution of PAH-8 can convert the blue emission into intensive sky blue emission after adding trifluoroacetic acid (TFA), and the solid film exhibits no fluorescence after fuming with TFA vapors, while fuming with triethylamine (TEA) vapors resulted in intensive green emission.

Perfluoroarene induces a pentapeptidic hydrotrope into a pH-tolerant hydrogel allowing naked eye sensing of Ca2+ ions

Self-assembly of a novel thermoresponsive, pyrene-appended oligopeptide sequence VPGKP (PyP) leads to the formation of spherical aggregates in water. The sizes of the globular aggregates of the peptide, PyP, strongly depend on the temperature of its suspension in water and decrease with the decrease in temperature showing a lower critical solution temperature (LCST) phenomenon. Furthermore, a pyrene-octafluoronaphthalene (OFN) 'pair' has been used as a supramolecular synthon to induce hydrogelation of PyP in the presence of an equimolar amount of OFN via complementary quadrupole-quadrupole interactions. The gel shows excellent pH tolerance and thixotropic behavior. Detailed studies suggest the existence of lamellar packing of the gelators in a right-handed helical fashion which yields globular aggregates. The globular aggregates are sticky in nature and form a gel via inter-globular interactions. Addition of Ca2+ ions reinforces the mechanical strength and also reduces the critical gelator concentration of the native gel through coordination with the free -COO- group of the gelator. Therefore, the present hydrogel system could further be used as a naked eye sensor of Ca2+ ions.

A 1,8-naphthalimide–pyridoxal conjugate as a supramolecular gelator for colorimetric read out of F− ions in solution, gel and solid states

Naphthalimide–pyridoxal conjugated gelator 1 has been designed and synthesized. Compound 1 which forms stable greenish yellow colored gel in DMSO : H₂O (8 : 1 v/v), shows selective sensing of F⁻ in solution, gel and solid states under different conditions.

Host–guest interaction enabled chiroptical photo-switching and enhanced circularly polarized luminescence

A supra-gelator from γ-CyD and a cyanostilbene gelator showed enhanced circularly polarized luminescence and enabled a reversible chiroptical as well as morphological photo-switching.

A simple and visual approach for enantioselective recognition through supramolecular gels with specific selectivity

(S)/(R)1 enantioselectively self-assemble to form a gel or solution with one enantiomer of (S)/(R)BINAM with specific selectivity.

Self-Reporting Inhibitors: A Single Crystallization Process To Obtain Two Optically Pure Enantiomers

Collection of two optically pure enantiomers in a single crystallization process can significantly increase the chiral separation efficiency but this is difficult to realize. Now a self-reporting strategy is presented for visualizing the crystallization process by a dyed self-assembled inhibitor made from the copolymers with tri(ethylene glycol)-grafting polymethylsiloxane as the main chain and poly(N⁶ -methacryloyl-l-lysine) as side chains. When applied with seeds together for the fractional crystallization of conglomerates, the inhibitors can label the formation of the secondary crystals and guide the complete separation process of two enantiomers with colorless crystals as the first product and red crystals as the second. This method leads to high optical purity of d/l-Asn⋅H₂ O (99.9 % ee for d-crystals and 99.5 % for l-crystals) in a single crystallization process. It requires a small amount of additives and shows excellent recyclability.

Alanine-Based Chiral Metallogels via Supramolecular Coordination Complex Platforms: Metallogelation Induced Chirality Transfer

Chiral self-assemblies constantly attract great interest because of their potential to provide insight into biological systems and materials science. Herein we report on the efficient preparation of alanine-based chiral metallacycles, rhomboids 1D and 1L and hexagons 2D and 2L using a Pt(II) ← pyridyl directional bonding approach. The metallacycles are subsequently assembled into nanospheres at low concentration, that generate chiral metallogels at high concentration driven by hydrogen bonding, hydrophobic and π-π interactions. The gels consist of microscopic chiral nanofibers with well-defined helicity, as confirmed by circular dichroism (CD) and scanning (SEM) and transmission electron (TEM) microscopies. Given these results, we expect this technique will not only unlock interesting new approaches to understand homochirality in nature but also allow the design of versatile soft materials containing chiral supramolecular cores.

A tetraphenylethylene-based acylhydrazone gel for selective luminescence sensing

A supramolecular gel based on dynamic covalent acylhydrazone bonding for selective and sensitive Cu²⁺ and subsequent CN⁻ detection has been reported.

(Super)gelators derived from push–pull chromophores: synthesis, gelling properties and second harmonic generation

New organogelators including push–pull chromophores are described and show that second harmonic generation active materials can be prepared without sophisticated processes.

Exploring the difference in xerogels and organogels through in situ observation

Solvent-gelator interactions play a key role in mediating organogel formation and ultimately determine the physico-chemical properties of the organogels and xerogels. The ethanol organogels of 1,4-bis[(3,4,5-trihexyloxy phenyl)hydrazide]phenylene (TC6) were investigated in situ by FT-IR, Raman and fluorescence spectra, and XRD, and it was confirmed that the intermolecular interaction and aggregation structure of TC6 ethanol organogels were quite different from those of xerogels. Simultaneously, unprecedented phase transition from organogel to suspension upon heating was observed in ethanol organogel, and the suspension phase exhibited lytropic liquid crystalline behaviour with a rectangular columnar structure. This study may open the possibility to design new gelators with a new dimension of versatility.

Self-Assembled Polydiacetylene Vesicle and Helix with Chiral Interface for Visualized Enantioselective Recognition of Sulfinamide

An l-glutamic acid terminated amphiphilic diacetylene was designed and found to self-assemble into vesicles in water and supramolecular gel with helical structures in mixed methanol/water solvent. Both the vesicles and the helices underwent topochemical photopolymerization under UV irradiation and changed to a blue color. During the self-assembly and photopolymerization, the chirality of localized l-glutamic acid was successfully transferred to polydiacetylene (PDA), which resulted in obvious CD signals in the PDA blue phase. Interestingly, the CD signals for PDA vesicles and helices were opposite due to the different packing modes in the PDA skeleton. However, although these two assembly systems own opposite supramolecular chirality, both of them showed the same enantioselective recognition of sulfinamide enantiomers, in which the assemblies with S-enantiomer turned red while the other remained blue in the presence of the R-enantiomer. It is suggested that the chiral interface composed of l-glutamic acid played an important role in the enantioselective recognition. This work revealed the function of molecular and supramolecular chirality in the supramolecular self-assembly system.