Search

The realization of persistent luminescence and in particular circularly polarized luminescence (CPL) of organic radicals remains a challenge due to their sensitivity to oxygen at ambient conditions and elusive excited state chirality control. Here, it is reported that UV‐irradiation on a supramolecular gel from a chiral triarylamine derivative, TPA‐Ala, led to the formation of luminescent radicals with bright CPL. TPA‐Ala can form an organogel in chloroform with blue emission and supramolecular chirality as demonstrated by both CD and CPL signals. Upon UV 365 nm irradiation, an emission color change from blue to cyan is observed due to the formation of photo‐induced radicals. Interestingly, it is found that the supramolecular gel radicals showed stable luminescence with a lifetime ≈ 10 days in dark environments and inverted CPL, which represents a scarce example with persistent CPL from doublet‐state due to oxygen isolation ability of the gel network. Furthermore, doping a guest dye, Rhodamine B (RhB), into the supramolecular gel (RhB/TPA‐Ala = 30% in molar ratio) successfully obtained a transient white‐light CPL through the superposition of photo‐induced radical and guest dye emissions. This work provides a useful methodology for the fabrication of radical‐based CPL materials via a supramolecular assembly approach. [ABSTRACT FROM AUTHOR]

The photophysical and chiroptical properties of a chiral biquinoline amphiphile were found to be closely related to its aggregate states. Photochromism through photo-induced radical and circularly polarized luminescence were realized in its gel state and thin film state, respectively. [ABSTRACT FROM AUTHOR]

To control the dimension of the supramolecular system was of great significance. We construct a two component self-assembly system, in which the gelator LHC18 and achiral azobenzene carboxylic acid could co-assembly and form gels. By modulating the stoichiometric ratio of the two components, not only the morphology could be transformed from 1D nanaotube to 0D nanospheres but also the supramolecualr chirality could be tuned. This work could provide some insights to the control of dimension and the supramolecular chirality in the two-component systems by simply modulating the stoichiometric ratio. [ABSTRACT FROM AUTHOR]

The chiral exciton couplings within a Y-shaped amphiphilic glutamide–cyanostilbene (GCS) could be significantly biased by solvent polarity and hydration effects, which led to sign inversion of both the circular dichroism and circularly polarized luminescence of the GCS assemblies. [ABSTRACT FROM AUTHOR]

A cyanostilbene conjugated gelator was incorporated into the cavities of cyclodextrins via the host–guest interaction and the resulting supra-gelator from γ-CyD enabled chiroptical photo-switching, while the other gels showed enhanced circularly polarized luminescences. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

By constructing a supramolecular light‐harvesting chiral nanotube in the aqueous phase, we demonstrate a cooperative energy and chirality transfer. It was found that a cyanostilbene‐appended glutamate compound (CG) self‐assembled into helical nanotubes exhibiting both supramolecular chirality and circularly polarized luminescence (CPL). When two achiral acceptors, ThT and AO, with different energy bands were co‐assembled with the nanotube, the CG nanotube could transfer its chirality to both of the acceptors. The excitation energy could be transferred to ThT but only be sequentially transferred to AO. During this process, the CPL ascribed to the acceptor could be sequentially amplified. This work provides a new insight into the understanding the cooperative chirality and energy transfer in a chiral supramolecular system, which is similar to the natural light‐harvesting antennas. [ABSTRACT FROM AUTHOR]

A naphthalene substituted histidine derivative was found to form an organogel showing circularly polarized luminescence (CPL) and the addition of non-fluorescent achiral benzoic acids could efficiently enhance the CPL via non-covalent interactions. [ABSTRACT FROM AUTHOR]

The selective interplay between dimensional morphology transition and signal transfer is an important feature for both nanomaterials and biosystems. While most of those reported examples considered either dimensional transition or signal transfer, the integrated interplay or selectivity for these two aspects in single self-assembled system has been rarely studied. Here, we report that a positively charged chiral π-building block could self-assemble into multidimensional nanostructures, which showed tunable circularly polarized luminescence (CPL). Impressively, when these CPL-active multidimensional structures interacted with two achiral dyes (positively charged ThT and negatively charged CNA), 3D nanocubes and 0D nanospheres showed neither chirality transfer nor energy transfer, while 2D nanoplates could successfully trigger a selective chirality or energy transfer depending on the charge type of acceptor dyes, which then emitted an enhanced CPL signal. This work demonstrated rational design of charged π-building block for the construction of dimension controllable and selective signal transfer self-assembly system, which might deepen the understanding the interplay of dimensional structures and signal transfer functions in natural and nano systems.

Binary supramolecular gels based on achiral azobenzene derivatives and a chiral chaperone gelator, long-alkyl-chain-substituted L-Histidine (abbreviated as LHC18) that could assist many nongelling acids in forming gels, were investigated in order to fabricate the chiroptical gel materials in a simple way. It was found that although the carboxylic acid-terminated achiral azobenzene derivatives could not form gels in any solvents, when mixed with LHC18 they formed the co-gels and self-assembled into various morphologies ranging from nanotubes and loose nanotubes to nanosheets, depending on the substituent groups on the azobenzene moiety. The ether linkage and the number of carboxylic acid groups attached to the azobenzene moiety played important roles. Upon gel formation, the localized molecular chirality in LHC18 could be transferred to the azobenzene moiety. Combined with the trans-cis isomerization of the azobenzene, optically and chiroptically reversible gels were generated. It was found that the gel based on azobenzene with two carboxylic acid groups and ether linkages showed clear optical reversibility but less chiroptical reversibility, whereas the gel based on azobenzene with one carboxylic acid and an ether linkage showed both optical and chiroptical reversibility. Thus, new insights into the relationship among the molecular structures of the azobenzene, self-assembled nanostructures in the gel and the optical and chiroptical reversibility were disclosed.