Bioinspired Toolkit Based on Intermolecular Encoder toward Evolutionary 4D Chiral Plasmonic Materials

摘要： Over the last two decades, nanophotonics, including plasmonics and metamaterials, have promised compelling opportunities for exotic control over light?matter interactions. The strong chiral light?matter interaction is a representative example. Three-dimensional (3D) chirality has existed naturally only in organic molecules and bio-organisms, but a negligible chiroptic effect was attained with these naturally occurring materials because of their small absorption cross sections. However, inspired by biological chirality, nanophotonic chiral materials have greatly expanded the design space of accessible chiroptic effects (e.g., pushing the chiral light?matter interaction to an exceptional regime, such as a broad-band circular polarizer, negative refractive index, and sensitive chiral sensing). Nevertheless, it is still a challenge to achieve precisely defined and dynamically reconfigurable chiral morphologies that further increase the chiroptic effect.

Formation of enhanced opposite one-handed chiral fields in heterodimer-film nanostructures

摘要： Plasmonic chirality has attracted a lot of interests because it could result in dramatically increased chiroptical interactions and offer many potential applications in chiral molecules analysis, catalysis, and other nanotechnology. In particular, one-handed chiral field is required in many applications for the reason that molecules are generally distributed randomly in some region of structures. In this work, benefiting from the coupling effect and energy focusing effect, we propose a heterodimer-film nanostructure to achieve one-handed chiral fields under linearly polarized light illumination. The results indicate that there are just opposite one-handed chiral fields in different gaps of the heterodimer-film nanostructure. The volume averaged optical chirality in the gaps can reach 102 and the optical chirality of hot spots can reach 103, which has potential applications in chiral sensing and Raman optical activity.

Optical Chirality Sensing with an Auxiliary-free Earth-abundant Cobalt Probe

摘要： Broadly useful chiroptical ee sensing remains challenging and typically involves carefully designed molecular receptors or supramolecular assemblies. Herein, we describe enantioselective sensing of 35 amino acids, amino phosphonic acids, hydroxy acids, amino alcohols and diamines with an auxiliary-free cobalt probe. Chiroptical analysis of the enantiomeric composition and concentration of minute sample amounts is achieved with high accuracy using earth-abundant cobalt salts and hydrogen peroxide as oxidant. Despite the absence of an auxiliary ligand, the cobalt assay is applicable to aromatic and aliphatic compounds and yields strong CD signals at high wavelengths. This method eliminates the general prerequisite for chromophoric metal ligands to generate chiroptical signals via ECCD effects or through analyte-to-ligand chirality induction, and it offers operational simplicity, cost-efficiency, waste reduction and speed.

Strength and toughness anisotropy in hexagonal boron nitride: An atomistic picture

摘要： Strength and toughness are two crucial mechanical properties of a solid that determine its ability to function reliably without undergoing failure in extreme conditions. While hexagonal boron nitride (hBN) is known to be elastically isotropic in the linear regime of mechanical deformation, its directional response to extreme mechanical loading remains less understood. Here, using a combination of density functional theory calculations and molecular dynamics simulations, we show that strength and crack nucleation toughness of pristine hBN are strongly anisotropic and chirality dependent. They vary nonlinearly with the chirality of the lattice under symmetry breaking deformation, and the anisotropic behavior is retained over a large temperature range with a decreasing trend at higher temperatures. An atomistic analysis reveals that bond deformation and associated distortion of electron density are nonuniform in the nonlinear regime of mechanical deformation, irrespective of the loading direction. This nonuniformity forms the physical basis for the observed anisotropy under static conditions, whereas reduction in nonuniformity and thermal softening reduce anisotropy at higher temperatures. The chirality-dependent anisotropic effects are well predicted by inverse cubic polynomials.

External Reversal of Chirality Transfer in Photoswitches

摘要： The transfer of stereoinformation is at the heart of asymmetric reactions. By incorporating the natural monoterpene L-menthone into the backbone of a diarylethene, we could achieve efficient chirality transfer upon photocyclization resulting in the preferred formation of one major closed isomer in a diastereomeric ratio (dr) of 85 : 15. More significantly, we were able to completely reverse the diastereomeric outcome of the ring-closure, simply by altering the chemical environment or the irradiation conditions. As a result, we could selectively accumulate the less favored minor closed isomer, with remarkable dr values of > 99 : 1 and 74 : 26, respectively. Computations reveal that a stability inversion after photocyclization is the basis for the observed unprecedented control over diastereoselectivity.

[Springer Tracts in Modern Physics] Parity-time Symmetry and Its Applications Volume 280 || Non-Hermitian Effects Due to Asymmetric Backscattering of Light in Whispering-Gallery Microcavities

摘要： A whispering-gallery microcavity is an open optical system which supports well con?ned counterpropagating electromagnetic waves. Deforming the boundary of the cavity or perturbing it by other means, e.g. by placing small scatterers near the boundary, leads to coherent backscattering of these waves inside the cavity. In general, this backscattering is asymmetric, i.e. the strength of scattering from the clockwise to the counterclockwise propagation direction is different from the other way around. This asymmetry is intrinsically tied to the non-Hermiticity of the system including the nonorthogonality of mode pairs and the coalescence of modes at exceptional points. We review and present new results on asymmetric backscattering with emphasis on its non-Hermitian effects. Several types of perturbed whispering-gallery cavities are considered. Different applications, such as single-particle detection with enhanced sensitivity, are discussed.

Cooperative Chirality and Sequential Energy Transfer in Supramolecular Light-harvesting Nanotube

摘要： By constructing a supramolecular light-harvesting chiral nanotube in aqueous phase, we demonstrated the cooperative energy and chirality transfer that revealed some new aspects. 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 such 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 more similar to the natural light-harvesting antennas.

Photoactive Functional Soft Materials (Preparation, Properties, and Applications) || Photochemical Chirality Induction and Inversion in Soft Materials

摘要： Chirality or “handedness” is a prerequisite of the biological world, where life exists in a specific chirality. In living organisms, almost all the sugars are exclusively right‐handed (d‐isomer), amino acids are left‐handed (l‐isomer), and DNA coils assemble into right‐handed helices. The reason behind this homochirality is still an unresolved issue. Inspired by the natural homochirality, the scientific community has been interested in exploring the mechanism of transmission of chirality from the molecular level of monomeric units to the macro‐ or supramolecular level, as well as the origin of chirality. The supramolecular chirality in nature from self‐assembled achiral molecules and its specific handedness play a crucial role in the evolution of life and the development of supramolecular materials. While the chirality of molecules is of configurational and conformational origin, supramolecular level chirality arises from the organization of molecules, with formation of a chiral superstructure by means of long‐range positional and orientational orders of molecules.

Cooperative Chirality and Sequential Energy Transfer in Supramolecular Light-harvesting Nanotube

摘要： By constructing a supramolecular light-harvesting chiral nanotube in aqueous phase, we demonstrated the cooperative energy and chirality transfer that revealed some new aspects. 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 such 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 more similar to the natural light-harvesting antennas.

Optically Switchable Helicenes for an Enantiodivergent Steglich Rearrangement