Hysteresis Nanoarchitectonics with Chiral Gel Fibers and Achiral Gold Nanospheres for Reversible Chiral Inversion

Abstract

Intelligent control over the handedness of circular dichroism (CD) is of special significance in self‐organized biological and artificial systems. Herein, we report a chiral organic molecule (R1) containing a disulfide unit self‐assembles into M‐type helical fibers gels, which undergoes chirality inversion by incorporating gold nanospheres due to the formation of Au−S bonds between R1 and gold nanospheres. Upon heating at 80 °C, the aggregation of gold nanospheres results in a disappearance of the Au−S bond, allowing the reversible switching back to M‐type helical fibers. The original chirality of M‐type fibers could also be retained by adding anisotropic gold nanorods. A series of characterization methods, involving CD, Raman, Infrared spectroscopy, electric microscopy, and small‐angle X‐ray scattering (SAXS) measurements were used to investigate the mechanism of chiral evolutions. Our results provide a facile way of fabricating hysteresis nanoarchitectonics to achieve dynamic supramolecular chirality using inorganic metallic nanoparticles.

Chiral Au Nanorods: Synthesis, Chirality Origin, and Applications

“…179 In general, the operation of chiral plasmonic nanosensors strongly relies on the interaction of chiral host and the achiral or chiral guest, leading to the amplification of a shift, a decrease or increase in the peaks of PCD response, or other unique spectral 147,151,180−185 Ac−Au NRs have been modified with probes for the ultrasensitive detection of targeted molecules, thanks to their sensitivity of chiral soft templates. In the schematic of chiral plasmonic nanosensors, the stimuli-responsiveness (temperatures, 186,187 pH, 188,189 light, 60,140,190−192 charging 193 ) of chiral soft templates can regulate the PCD profiles of chiral Au NRs. The slight change in the intensity and position of PCD shows the ultrasensing of external stimuli (Figure 6a).…”

“…Ac–Au NRs have been modified with probes for the ultrasensitive detection of targeted molecules, thanks to their sensitivity of chiral soft templates. In the schematic of chiral plasmonic nanosensors, the stimuli-responsiveness (temperatures, , pH, , light, ,,− charging) of chiral soft templates can regulate the PCD profiles of chiral Au NRs. The slight change in the intensity and position of PCD shows the ultrasensing of external stimuli (Figure a).…”

Reversible Inversion of Circularly Polarized Luminescence in a Coassembly Supramolecular Structure with Achiral Sulforhodamine B Dyes

“…As shown in Figure 4a, the appearance of an N−H stretching vibration band at 3438 cm −1 , amide I and II bands at 1630 cm −1 (C�O stretching), and 1545 cm −1 (N−H bending) indicated the existence of hydrogen bonds in a L4/SDS (1:6) supramolecular structure (black trace). 53,54 After the SRB dyes were added, the peaks at 3438 cm −1 associated with N−H stretching showed a significant decline (Figures 4a and S28), suggesting the destruction of intramolecular hydrogen bonds. As shown in Figure 4b, SAXS unveiled the evolution of a supramolecular structure caused by the addition achiral SRB molecules.…”

Large Optical Asymmetry in Silver Nanoparticle Assemblies Enabled by CH−π Interaction-Mediated Chirality Transfer

“…In addition to their intrinsic optical activity associated with the chiral morphs of the NPs, the plasmonic chirality can also be induced through the following two approaches: (1) placing the chiral molecules at the “hot spots” of the plasmonic structures that induce the dipolar interactions between chiral molecules and plasmonic NPs; − (2) positioning the plasmonic NPs into chiral geometry that induces the plasmonic coupling between adjacent NPs. , The latter one is dramatically affected by the asymmetry of the templates, size, shape, and compositions of the NPs. Up to date, diversified chiral templates including biomacromolecules, block copolymers, organogels, liquid crystals, supramolecular polymers and silica, have been explored to engineer a large g -factor of the plasmonic chirality. − Seminal work by Liu, Kotov, and de Moura shows that large optical asymmetry g -factor of 0.12 is attained through co-assembly of Au nanorods and an amyloid protein (human islet amyloid polypeptides, hIAPPs), where the assembly of nanorods onto the hIAPP fibrils leads to discrete twisted nanorod assemblies with long-range order . The shape anisotropy of the Au nanorods, addressed in terms of the aspect ratio, plays a vital role in achieving such a high g -factor.…”