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Contrast of optical activity and rogue wave propagation in chiral materials
摘要： We report the contrast of optical activity and properties of nonparaxial optical rogue waves for the higher-order nonparaxial chiral nonlinear Schr?dinger (NLS) equation. The latter describes the propagation of ultrashort optical pulses in chiral optical fibers. Both first- and second-order rogue wave solutions are investigated analytically by the modified Darboux transformation (MDT) and numerically by one pseudo-spectral method. The interplay of chiral materials on rogue wave propagation is elucidated, and the results can be applied on optical communication and in others physical systems.
关键词： Chirality and optical activity,Chiral optical fibers,Rogue wave propagation,Chiral materials
更新于2025-09-23 15:23:52
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Mass Production of High-Purity Semiconducting Carbon Nanotubes by Hydrochloric Acid-assisted Gel Chromatography
摘要： Mass production of high-purity semiconducting single-wall carbon nanotubes (s-SWCNTs) is critical for their application in the electronic and optoelectronic devices. Here we reported a method for the high-efficiency separation of high-purity s-SWCNTs with the acid-assisted gel chromatography, in which hydrochloric acid (HCl) was used to selectively oxidize metallic SWCNTs (m-SWCNTs) and enhance the difference in the interaction of metallic and semiconducting nanotubes with gel. Specifically, the concentration of HCl in the eluent was gradually increased to elute the carbon nanotubes adsorbed in the gel column step by step. The m-SWCNTs were firstly eluted at a low HCl concentration, and high-purity s-SWCNTs were selectively eluted at a higher HCl concentration. The final residues containing a relatively high content of m-SWCNTs and amorphous carbon impurities were left in the gel columns. Optical and electrical characterizations confirmed that the purity of the s-SWCNTs extracted from various raw SWCNT materials, especially CoMoCAT (7, 6), was improved greatly. Moreover, multiple single-chirality SWCNTs were firstly separated from the purified semiconducting CoMoCAT (7, 6) nanotubes. Our present work provides a simple and controllable way for the mass separation of high-purity s-SWCNTs and single-chirality species, which would accelerate their application in the field of electronics, optoelectronics and bio-imaging.
关键词： hydrochloric acid,separation,gel chromatography,Semiconducting carbon nanotubes,single-chirality
更新于2025-09-23 15:23:52
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Double Twisted Photonic Honeycomb Frameworks with Mesoporous Structures
摘要： In nature, materials such as shell, bone, silk, and wood are assembled with hierarchical structures that span lengths from nanometers to centimeters. These biological materials are fascinating targets for replication and mimicry, often owing to their remarkable properties. The intricate and periodic structure of the snow crab (Chionoecetes opilio) exoskeleton that renders it iridescent is described here. It is discovered that the snow crab has a double twisted photonic honeycomb structure constructed by left-handed rotation of chitin nanofibrils around cavities throughout its shell. This new chiral framework provides a foundation for exploring chiral photonics and materials. With the goal of mimicking this intricate network, the iridescent mineralized chitin shell is successfully transferred to calcite, carbon, apatite, and fluorapatite/chitin materials with structural replication. It is shown that the sophisticated organization of the iridescent crab shell leads these new materials to have a distinctive macroscopic combination of multilevel chirality, honeycomb channels, and mesoporosity. These solid-state transformations of snow crab exoskeletons will open the path to making complex hierarchical frameworks of functional porous materials through bioinspired templating.
关键词： honeycomb,coloration,biomimicry,chirality,structural order
更新于2025-09-23 15:23:52
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Control of Circularly Polarized Luminescence by Orientation of Stacked π-Electron Systems
摘要： New planar chiral building blocks based on 4,7,12,15-tetrasubstituted [2.2]paracyclophanes were obtained via a synthetic route involving an optical resolution step. Planar chiral enantiomers, comprising of two fluorophores that were stacked to form a V-shaped higher-ordered structure, were synthesized from these building blocks. The V-shaped molecules emitted intense circularly polarized luminescence (CPL). Their chiroptical properties were compared with those of X-shaped molecules bearing the same two fluorophores stacked together. CPL sign of the X-shaped molecule was opposite to that of the V-shaped molecule, which is supported by the theoretical results, indicating that CPL sign can be controlled by the orientation of the stacked fluorophores.
关键词： circularly polarized luminescence,planar chirality,higher-ordered structure,[2.2]paracyclophane
更新于2025-09-23 15:23:52
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Chiral Analysis || Quantitative Chiral Analysis by Molecular Rotational Spectroscopy
摘要： This chapter presents early results from the emerging field of quantitative chiral analysis by molecular rotational spectroscopy. The focus is on the development of measurement techniques to solve the challenging analytical chemistry problem of determining the ratios of all stereoisomers for a chiral molecule. This analysis becomes particularly challenging as the number of chiral centers in the molecule increases. Furthermore, this area of spectroscopy has the goal of creating measurement techniques that can be used directly on complex chemical mixtures to perform chiral analysis without the need of chemical separation by chromatography. Examples of chemical samples that fall into this category include natural products like essential oils from plants that are a rich mixture of volatile species and reaction flask samples where stereospecific chemical reactions are performed and which contain unreacted reagents, desired and undesired reaction products, and solvents in the mixture.
关键词： stereoisomers,chiral tag,diastereomers,molecular rotational spectroscopy,chirality,enantiomers,three-wave mixing,analytical chemistry,quantitative chiral analysis
更新于2025-09-23 15:23:52
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Topological valley pumping in Weyl semimetals
摘要： We investigate the topological pumping effect in Weyl semimetals, subject to the modulation of two ac electric fields along y and z directions, respectively. We show that the pumping effect originates from the anomalous velocity related to the Berry curvature. The direction of the pumping current is dependent on the chirality of the Weyl fermions. While the total particle current is vanishing because the Weyl points of opposite chirality always come in pairs in Weyl semimetals, the pump gives rise to a net chirality current or valley current. The noiseless valley current generated can be useful in valleytronic applications.
关键词： Valleytronics,Chirality,Topological pumping effect,Valley current,Weyl semimetal
更新于2025-09-23 15:23:52
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Towards the design of optically active thiophene S-oxides using quantum chemistry
摘要： The importance of axially chiral biaryls has risen steeply in the recent decades. This structural motif proved to be successful in catalytic asymmetric synthesis and the configuration of the biaryl axis is decisive for biological activity. A new approach for the atroposelective synthesis of biaryls would be through a cycloaddition between an enantiopure phenyl-substituted thiophene S-oxide and an alkyne. Importantly, the chiral center of the thiophene S-oxide needs to be stable enough to avoid pyramidal inversion during the cycloaddition. Since the racemization of thiophene monoxides has been scarcely investigated so far, we perform a thorough quantum chemical study on the inversion barriers of a large number of chiral thiophene S-oxide derivatives. Our main goal is to identify substitution patterns leading to stable atropisomers at room temperature. Appealingly, the role of the stereoelectronic effects and position of the substituents as well as the importance of aromaticity on the pyramidal inversion barrier is elucidated for the first time.
关键词： thiophene sulfoxides,axial chirality,DFT,enantiomerization,aromaticity
更新于2025-09-23 15:23:52
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Spin-Selective Transmission in Chiral Folded Metasurfaces
摘要： Controlling the spin angular momentum of light (or circular polarization state) plays a crucial role in the modern photonic applications such as optical communication, circular dichroism spectroscopy, and quantum information processing. However, the conventional approaches to manipulate the spin of light require naturally occurring chiral or birefringent materials of bulky sizes due to the weak light-matter interactions. Here we experimentally demonstrate an approach to implement spin-selective transmission in the infrared region based on chiral folded metasurfaces that are capable of transmitting one spin state of light while largely prohibiting the other. Due to the intrinsic chirality of the folded metasurface, a remarkable circular dichroism as large as 0.7 with the maximum transmittance exceeding 92% is experimentally demonstrated. The giant circular dichroism is interpreted within the framework of charge-current multipole expansion. Moreover, the intrinsic chirality can be readily controlled by manipulating the folding angle of the metasurface with respect to the cardinal plane. Benefiting from its strong chirality and spin-dependent transmission characteristics, the proposed folded metasurface may be applied to a range of novel photon-spin selective devices for optical communication technologies and bio-photonics.
关键词： sub-wavelength optics,Folded metasurface,intrinsic chirality,spin-selective transmission
更新于2025-09-23 15:23:52
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Chiral Recognition of L- and D- Amino Acid by Porphyrin Supramolecular Aggregates
摘要： We report of the interactions between four amino acids lysine (Lys), arginine (Arg), histidine (His), and phenylalanine (Phe) with the J-aggregates of the protonated 5,10,15,20-tetrakis(4-sulfonatophenyl)-porphyrin H4TPPS. Several aspects of these self-assembled systems have been analyzed: (i) the chiral transfer process; (ii) the hierarchical effects leading to the aggregates formation; and, (iii) the influence of the amino acid concentrations on both transferring and storing chiral information. We have demonstrated that the efficient control on the J-aggregates chirality is obtained when all amino acids are tested and that the chirality transfer process is under hierarchical control. Finally, the chiral porphyrin aggregates obtained exhibit strong chiral inertia.
关键词： porphyrin,self-assembly,amino acid,circular dichroism,supramolecular chirality
更新于2025-09-23 15:22:29
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Synthesis and photochromic properties of azobenzene-derived glycomacrolactones Chaoqi Lin,[a] Stéphane Maisonneuve,[a] Cyril Theulier,[a] and Juan Xie*[a]
摘要： Reversible photocontrol of glycosides and glycoconjugates structures is a very attractive approach to modulate, in a spatiotemporal way, the various properties and biological activities of carbohydrates. We have synthesized three new azobenzene-derived glycomacrolactones from thioglycopyranosides. The synthesized cyclic glycoazobenzenes can be reversibly photoisomerized between E and Z isomers with high fatigue resistance. 1H NMR study shows that E→Z isomerization of glycomacrocycles induces large conformational change of the macrocyclic structures, without changing sugar 4C1 chair conformation. The Z-glycoazobenzenes can be thermally converted back to the E-isomers. Interestingly, these 16 to 17-membered Z-glycomacrolactones display higher thermal stability than the reported macrocyclic azobenzenes, with the half-life varied from 37 to 72 days. The excellent photoswitching property and bi-stability of the synthesized glycoazobenenes open a new opportunity for the convergent synthesis of diastereomers of glycomacrocycles. Furthermore, chiroptical properties have been observed for both E and Z glycomacrolactones. The geometry of different isomers of macrocycles has been optimized with DFT calculations. Theoretical CD spectra obtained by TD-DFT suggest that the E and Z glycomacrocycles adopt preferentially (P) helical structure for the azobenzene moiety.
关键词： photochromism,azo compounds,carbohydrates,macrolactones,chirality
更新于2025-09-23 15:22:29