Disassembly of spherical structures into nanohelices by good solvent dilution.

Supramolecular self-assembly of low molecular weight molecules into various organic nanostructures has attracted considerable research interest. However, preparing organic nanostructures through a top-down method, such as the disassembly of one large structure into many smaller nanoscale nanostructures, still remains a big challenge. Here, we make use of anti-solvent method to regulate the hierarchical self-assembly of an achiral C-symmetric molecule in THF/water to prepare various nanostructures, including spherical structures, nanofibers, nanoribbons and nanotwists.

Tunable molecular packing modes H- or J-aggregates in the supramolecular helical nanostructures from an achiral symmetric molecule.

The self-assembly of a -symmetric molecule benzene-1,3,5-tricarboxylate substituted with methyl cinnamate (BTECM) has been investigated by a reprecipitation method in HO and cetyltrimethylammonium bromide (CTAB) aqueous solution, respectively. The nanostructures and characteristics of the assemblies were monitored by UV-Vis spectroscopy, fluorescence (FL) spectroscopy, circular dichroism (CD) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that helical nanostructures were successfully assembled from the achiral molecule BTECM.

Circularly Polarized Organic Room Temperature Phosphorescence from Amorphous Copolymers.

Organic optoelectronic functional materials featuring circularly polarized emission and persistent luminescence represent a novel research frontier and show promising applications in data encryption, displays, biological imaging, and so on. Herein, we present a simple and universal approach to achieve circularly polarized organic phosphorescence (CPP) from amorphous copolymers by the incorporation of axial chiral chromophores into polymer chains via radical cross-linked polymerization. Our experimental data reveal that copolymers (/)-PBNA exhibit a maximum CPP efficiency of 30.

Asymmetric catalysis mediated by a mirror symmetry-broken helical nanoribbon.

Although chirality has been recognized as an essential entity for life, it still remains a big mystery how the homochirality in nature emerged in essential biomolecules. Certain achiral motifs are known to assemble into chiral nanostructures. In rare cases, their absolute geometries are enantiomerically biased by mirror symmetry breaking.

Self-Assembly of Hierarchical Chiral Nanostructures Based on Metal-Benzimidazole Interactions: Chiral Nanofibers, Nanotubes, and Microtubular Flowers.

Controlled hierarchical self-assembly of synthetic molecules into chiral nanoarchitectures to mimic those biological chiral structures is of great importance. Here, a low-molecular-weight organogelator containing a benzimidazole moiety conjugated with an amphiphilic l-glutamic amide has been designed and its self-assembly into various hierarchical chiral nanostructures is investigated. Upon gel formation in organic solvents, 1D chiral nanostructure such as nanofiber and nanotube are obtained depending on the solvents.

Symmetry Breaking in the Supramolecular Gels of an Achiral Gelator Exclusively Driven by π-π Stacking.

Supramolecular symmetry breaking, in which chiral assemblies with imbalanced right- and left-handedness emerge from achiral molecular building blocks, has been achieved in the organogels of a C3-symmetric molecule only via π-π stacking. Specifically, an achiral C3-symmetric benzene-1,3,5-tricarboxylate substituted with methyl cinnamate through ester bond was found to form organogels in various organic solvents. More interestingly, when gels formed in cyclohexane, symmetry breaking occurred; i.

Chiral Nanoarchitectonics: Towards the Design, Self-Assembly, and Function of Nanoscale Chiral Twists and Helices.

Helical structures such as double helical DNA and the α-helical proteins found in biological systems are among the most beautiful natural structures. Chiral nanoarchitectonics, which is used here to describe the hierarchical formation and fabrication of chiral nanoarchitectures that can be observed by atomic force microscopy (AFM), scanning tunneling microscopy (STM), scanning electron microscopy (SEM), or transmission electron microscopy (TEM), is one of the most effective ways to mimic those natural chiral nanostructures. This article focuses on the formation, structure, and function of the most common chiral nanoarchitectures: nanoscale chiral twists and helices.

Strong circularly polarized luminescence from the supramolecular gels of an achiral gelator: tunable intensity and handedness.

Although the importance of circularly polarized luminescence (CPL) materials has been widely recognized, the CPL responses of supramolecular gels are still rarely studied. Moreover, developing CPL materials based on supramolecular gels is of great significance, due to their special advantages and important applications. Herein, we report the first circularly polarized supramolecular gels self-assembled exclusively from a simple achiral -symmetric molecule.

Supramolecular copolymers obtained from two-component gels: metal ion-mediated cross-linking, enhanced viscoelasticity and supramolecular yarns.

The hydrogels based on the co-assembly of bolaamphiphilic L-histidine and 2,2'-bipyridine-dicarboxylic acids were transformed into viscoelastic supramolecular polymers by cross-linking with Cu(II) ions, and macroscopic supramolecular yarns were obtained by direct drawing from a dilute aqueous solution of the supramolecular polymers.

Macroscopic chirality of supramolecular gels formed from achiral tris(ethyl cinnamate) benzene-1,3,5-tricarboxamides.

A C3 -symmetric benzene-1,3,5-tricarboxamide substituted with ethyl cinnamate was found to self-assemble into supramolecular gels with macroscopic chirality in a DMF/H2 O mixture. The achiral compound simultaneously formed left- and right-handed twists in an unequal number, thus resulting in the macroscopic chirality of the gels without any chiral additives. Furthermore, ester-amide exchange reactions with chiral amines enabled the control of both the handedness of the twists and the macroscopic chirality of the gels, depending on the structures of the chiral amines.

Sensitive and photo-triggered transformation of hierarchical helices assembled from achiral bolaamphiphiles.

Chiral nanostructures, normally formed by chiral molecules, play an essential role in natural systems. The helical assemblies constructed by achiral molecular building blocks are still rare and their regulating mechanisms have not been well studied. An achiral cinnamoyl-terminated bolaamphiphile with three methylene unit spacers was found to self-assemble into hierarchically helical nanostructure.

Tuning the gelation ability of racemic mixture by melamine: enhanced mechanical rigidity and tunable nanoscale chirality.

Understanding the relationship between molecular chirality of the gelators and the properties of the assembled supramolecular gels could be very important for developing novel functional soft matters. Although mixing the enantiomers with different molar ratios has been proved to be useful for modulating supramolecular assemblies, usually the racemates of different chiral molecules are not good gelators. In this study, the coassembly of the glutamic acid-based bolaamphiphile racemate and melamine was found to form hydrogels, while the assembly of the racemate only produced precipitates.

H-bond and π-π stacking directed self-assembly of two-component supramolecular nanotubes: tuning length, diameter and wall thickness.

A series of supramolecular nanotubes with fine-tuned length, diameter and wall thickness were obtained from co-assembly of an L-glutamic acid based bolaamphiphile (HDGA) and melamine with different molar ratios. The changes in tubular nanostructures were found to be dependent on different self-assembly mechanisms.