Chiral Cavity Research Articles

A chiral metal-organic framework/cyclodextrin sensing interface for the chiral discrimination of tryptophan enantiomers.

A chiral metal-organic framework (CMOF) was synthesized by introducing L-histidine (L-His) to zeolitic imidazolate framework-8 (ZIF-8) and then grafting with carboxymethyl-β-cyclodextrin (CM-β-CD). Compared with L-His-ZIF-8, the CM-β-CD-functionalized L-His-ZIF-8 (L-His-ZIF-8-CD) showed significantly enhanced discrimination ability for the tryptophan (Trp) enantiomers owing to the inherent chirality of CM-β-CD. The specificity of the chiral interface was also studied, and the results indicated that the discrimination ability for Trp enantiomers is significantly stronger than that for the enantiomers of cysteine (Cys) and tyrosine (Tyr), which might be due to the better matching between the indole ring of Trp and the chiral cavity of CM-β-CD.

Towards Chiral Lasing from All-Solution Processed Flexible Perovskite Nanocrystal-Liquid Crystal Membrane.

Circularly polarized (CP) coherent light sources are of great potential for various advanced optical applications spanning from display/imaging to data processing/encryption and quantum communication. Here we report the first demonstration of CP amplified spontaneous emission (ASE)/lasing from a free-standing and flexible membrane device consisting of perovskite nanocrystals (PNCs) and cholesteric liquid crystal layers sandwiched within a Fabry-Perot cavity architecture. The chiral liquid crystal cavity enables the generation of CP light from the device. The device is completely solution-processable, and displays CP ASE with record dissymmetry factor (glum ) as high as 1.4, which is 3 orders of magnitude higher as compared with glum of CP luminescence of chiral ligand-capped colloidal PNCs. The device exhibits ultra-flexibility as the ASE intensity remains unchanged after repeated 100 bending cycles and it is stable for more than 3 months with 80% of its original intensity. Furthermore, the ultra-flexibility enabled the generation of ASE from various objects of different geometric surfaces covered with the flexible perovskite membrane device. This work not only demonstrates the first CP ASE from PNCs membrane with extremely high glum but also opens the door toward the fabrication of ultra-flexible, extremely stable, and all solution-processable perovskite chiral laser devices. This article is protected by copyright. All rights reserved.

Tunable chiral photonic cavity based on multiferroic layers.

Realization of externally tunable chiral photonic sources and resonators is essential for studying and functionalizing chiral matter. Here, oxide-based stacks of helical multiferroic layers are shown to provide a suitable, electrically-controllable medium to efficiently trap and filter purely chiral photonic fields. Using analytical and rigorous coupled wave numerical methods we simulate the dispersion and scattering characteristics of electromagnetic waves in multiferroic heterostructures. The results evidence that due to scattering from the spin helix texture, only the modes with a particular transverse wavenumber form standing chiral waves in the cavity, whereas all other modes leak out from the resonator. An external static electric field enables a nonvolatile and energy-efficient control of the vector spin chirality associated with the oxide multilayers, which tunes the photonic chirality density in the resonator.

Strong Coupling in Chiral Cavities: Nonperturbative Framework for Enantiomer Discrimination

Strong Coupling in Chiral Cavities: Nonperturbative Framework for Enantiomer Discrimination

Chiral electroluminescence from thin-film perovskite metacavities.

Chiral light sources realized in ultracompact device platforms are highly desirable for various applications. Among active media used for thin-film emission devices, lead-halide perovskites have been extensively studied for photoluminescence due to their exceptional properties. However, up to date, there have been no demonstrations of chiral electroluminescence with a substantial degree of circular polarization (DCP) based on perovskite materials, being critical for the development of practical devices. Here, we propose a concept of chiral light sources based on a thin-film perovskite metacavity and experimentally demonstrate chiral electroluminescence with a peak DCP approaching 0.38. We design a metacavity created by a metal and a dielectric metasurface supporting photonic eigenstates with a close-to-maximum chiral response. Chiral cavity modes facilitate asymmetric electroluminescence of pairs of left and right circularly polarized waves propagating in the opposite oblique directions. The proposed ultracompact light sources are especially advantageous for many applications requiring chiral light beams of both helicities.

Non‐Reciprocal Cavity Polariton with Atoms Strongly Coupled to Optical Cavity

AbstractBreaking the time‐reversal symmetry of light is of great importance for fundamental physics and has attracted increasing interest in the study of non‐reciprocal photonic devices. Here, a chiral cavity quantum electrodynamics system with multiple atoms strongly coupled to a Fabry–Pérot cavity is experimentally demonstrated. By polarizing the internal quantum state of the atoms, the time‐reversal symmetry of the atom‐cavity interaction is broken. The strongly coupled atom‐cavity system can be described by non‐reciprocal quasiparticles, that is, the cavity polariton. When it works in the linear regime, the inherent nonreciprocity makes the system work as a single‐photon‐level optical isolator. Benefiting from the collective enhancement of multiple atoms, an isolation ratio exceeding 30 dB on the single‐quanta level (≈ 0.1 photon on average) is achieved. The validity of the non‐reciprocal device under zero magnetic field and the reconfigurability of the isolation direction are also experimentally demonstrated. Moreover, when the cavity polariton works in the nonlinear regime, the quantum interference between polaritons with weak anharmonicity induces non‐reciprocal nonclassical statistics of cavity transmission from coherent probe light.

Homochiral Zeolitic Imidazolate Framework with Defined Chiral Microenvironment for Electrochemical Enantioselective Recognition.

The recognition and separation of chiral molecules with similar structure are of great industrial and biological importance. Development of highly efficient chiral recognition systems is crucial for the precise application of these chiral molecules. Herein, a homochiral zeolitic imidazolate frameworks (c-ZIF) functionalized nanochannel device that exhibits an ideal platform for electrochemical enantioselective recognition is reported. Its distinct chiral binding cavity enables more sensitive discrimination of tryptophan (Trp) enantiomer pairs than other smaller chiral amino acids owing to its size matching to the target molecule. It is found that introducing neighboring aldehyde groups into the chiral cavity will result in an inferior chiral Trp recognition due to the decreased adsorption-energy difference of D- and L-Trp on the chiral sites. This study may provide an alternative strategy for designing efficient chiral recognition devices by utilizing the homochiral reticular materials and tailoring their chiral environments.

Chiral Polaritonics: Analytical Solutions, Intuition, and Use.

Preferential selection of a given enantiomer over its chiral counterpart has become increasingly relevant in the advent of the next era of medical drug design. In parallel, cavity quantum electrodynamics has grown into a solid framework to control energy transfer and chemical reactivity, the latter requiring strong coupling. In this work, we derive an analytical solution to a system of many chiral emitters interacting with a chiral cavity similar to the widely used Tavis-Cummings and Hopfield models of quantum optics. We are able to estimate the discriminating strength of chiral polaritonics, discuss possible future development directions and exciting applications such as elucidating homochirality, and deliver much needed intuition to foster the newly flourishing field of chiral polaritonics.

Enantioseparation, quantification, molecular docking and molecular dynamics study of five β-adrenergic blockers on Lux-Cellulose-2 column

Enantioseparation of five β-adrenergic blockers was studied using two mobile phases on a cellulose tris(3‐chloro‐4‐methylphenylcarbamate) (Lux-Cellulose-2) chiral column in normal phase mode. The first mobile phase composed of n-hexane: ethanol: diethylamine 60: 40: 0.1 by volume has successfully resolved the chromatographic peaks of three pairs of β-adrenergic blockers namely, bisoprolol, carvedilol and atenolol. A mixture of n-hexane: ethanol: diethyl amine 75: 25: 0.1 by volume was used as the second mobile phase to separate the four pairs of enantiomers, metoprolol, carvedilol, nebivolol and atenolol with high resolution values. The mobile phases were pumped at a flow rate 1 mL/min with column temperature 25 °C using a UV detector at 230 nm. Molecular docking simulations of the five pairs of enantiomers was carried out in the cavities of the chiral stationary phase to gain a better understanding of the interaction between analyte enantiomers and chiral stationary phase and to better understand the mechanism of chiral recognition. According to the results, hydrogen bond interactions and π-π- interactions were the main types of interaction involved in the chiral recognition. Molecular dynamics simulation was performed to investigate the solvent effect on the interaction of the five pair of enantiomers in the chiral stationary phase cavity under dynamic conditions.

Excitation of Chiral Cavity Plasmon Resonances in Film‐Coupled Chiral Au Nanoparticles

AbstractChiral plasmonic nanostructures have attracted increasing attention because of their superchiral near‐fields as well as strong far‐field chiral optical response. Recently, the development of chemical synthesis methods enabled the large‐scale manufacturing of three‐dimensional colloidal chiral plasmonic nanocrystals. Further improving the chiral optical response of such nanostructures will greatly facilitate their practical applications. In this work, it is found both in calculations and experiments that chiral cavity plasmon resonances can be excited in film‐coupled chiral Au helicoid nanoparticles, enabling the significant enhancement of the nanostructure chiral optical response. In addition, it is demonstrated from simulation that the chiral cavity mode can modulate the emission polarization of a point electric dipole placed in the nanocavity formed by the nanoparticle and the Au film, allowing the emission of almost circularly polarized photons by the linear dipole with the emission circular polarization anisotropy factor reaching as high as 93%. The film‐coupled chiral plasmonic nanoparticles therefore provide a promising platform for the construction of advanced chiral optical devices such as on‐chip nonreciprocal nanoscale light sources, chiral plasmonic sensors, chiral metamaterials, plasmonically enabled valleytronic devices, and nanophotonic circuits for future on‐chip communication applications.

Chiral discrimination in helicity-preserving Fabry-Pérot cavities

We theoretically study circular dichroism of chiral molecules embedded inside a helicity-preserving Fabry-P\'erot cavity. We find an increase of the intrinsic chiroptical response of the molecules by 2 orders of magnitude and report the first clear signature of chiral cavity polaritons upon entering the regime of strong light-matter coupling. We study a cavity design based on two dielectric photonic crystal mirrors acting, in a narrow frequency range, as efficient polarization cross-converters in transmission for one polarization and almost perfect reflectors for the other polarization. We show that a Pasteur medium hosted inside such a cavity can couple efficiently to both the outside of the cavity and to the helicity-preserving mode, inheriting an enhanced chiral character. We expect such a device to be useful in the future to design ultrasensitive chiral sensors for optics and stereochemistry.

Air-tolerant upconverted circularly polarized luminescence enabled by confined space of chiral micelle.

Circularly polarized luminescence (CPL) has been widely demonstrated that the circular polarization in excited state can be significantly amplified through the triplet-triplet annihilation-based upconversion (TTA-UC) luminescence process in various chiral nano-assemblies. However, constructing such an upconverted circularly polarized luminescence (UC-CPL) system in the aqueous phase remains a challenge. In this work, a kind of amphiphilic chiral cationic gemini surfactant is utilized to construct chiral spherical micelle in the aqueous phase, whose internal chiral cavity can provide a hydrophobic and deoxygenated environment for air-sensitive TTA-UC system. In addition, due to the co-assembly process between the emitters and chiral micelles, achiral emitters of upconversion pairs exhibit induced chiroptical properties. More importantly, the luminescence dissymmetry factor (glum ) can be amplified by one order of magnitude through TTA-UC process. This work provides an effective and useful strategy for realizing UC-CPL in aqueous phase.

Calix[4]arene-like Chiral Co4 and Zn4 Metallacycles

We report two pairs of enantiomers of Co(II)- and Zn(II)-based metallacycles constructed by coordination-driven self-assembly between homochiral 1,1′-bi-2-naphthol-derived ligands featuring two kinds of coordination pockets and transition-metal ions. Remarkably, they exhibit calix[4]arene-like topological structures and fascinating chiral cavities, having potential in enantioselective recognition.

Recognition of d-Glucose in Water with Excellent Sensitivity, Selectivity, and Chiral Selectivity Using γ-Cyclodextrin and Fluorescent Boronic Acid Inclusion Complexes Having a Pseudo-diboronic Acid Moiety.

Fluorescence recognition of d-glucose in water with excellent sensitivity, selectivity, and chiral selectivity is desired because d-glucose is an essential component in biological and pathological processes. We report an innovative approach that exploits the 1:2 stoichiometric inclusion complexes of γ-cyclodextrin (γ-CyD) with two molecules of fluorescent monoboronic acid-based receptors, which form a pseudo-diboronic acid moiety as the recognition site for d-glucose in water. Two monoboronic acids (1F and 2N) were easily synthesized without heating or column purification. The 1:2 stoichiometric inclusion complexes (1F/γ-CyD and 2N/γ-CyD) were prepared in a mixture of dimethyl sulfoxide/water (2/98 in v/v) by mixing γ-CyD and the corresponding monoboronic acids. Both 1F/γ-CyD and 2N/γ-CyD exhibited strong turn-on response to d-glucose with excellent selectivity over nine other saccharides in the water-rich solvent at pH 7.4 owing to the ditopic recognition of d-glucose by the pseudo-diboronic acid moieties. The limits of detection of 1F/γ-CyD and 2N/γ-CyD for d-glucose were 1.1 and 1.8 μM, respectively, indicating the remarkable sensitivity for the detection of d-glucose at μM levels. 1F/γ-CyD and 2N/γ-CyD also demonstrated chiral-selective recognition of d-glucose, which is apparent from the 2.0- and 6.3-fold enhancement of fluorescence by the addition of d-glucose relative to l-glucose addition, owing to the chiral pseudo-diboronic acid moieties produced by the chiral γ-CyD cavity. To the best of our knowledge, 2N/γ-CyD has the highest d/l selectivity among hitherto reported fluorescent diboronic acid-based receptors.

Multiselective Diels–Alder Reaction of α-Arylacroleins Catalyzed by Boron Tribromide-Assisted Chiral Phosphoric Acids

A multiselective Diels-Alder (DA) reaction of α-arylacroleins with cyclopentadiene using BBr3-assisted chiral BINOL-derived phosphoric acid catalysts has been developed. This unusual exo- and enantioselective DA reaction can be multicontrolled by the chiral cavity of the in situ-formed acid-base cooperative catalysts, in particular, suppressing the competitive hetero Diels-Alder (HDA) reaction effectively.

Single-Handedness Chiral Optical Cavities

Geometrical chirality is a universal property encountered on very different length scales ranging from geometrical shapes of living organisms to drug and DNA molecules. The interaction of chiral matter with chiral light, that is, an electromagnetic field possessing a certain handedness, underlies our ability to discriminate enantiomers of chiral molecules. In this context, it is often desired to have an optical cavity that efficiently couples to only a specific (right or left) molecular enantiomer and does not couple to the opposite one. Here, we demonstrate a single-handedness chiral optical cavity supporting only an eigenmode of a given handedness and lacking modes having the opposite one. Resonant excitation of the cavity with light of appropriate handedness enables the formation of a chiral standing wave with a uniform chirality density, while the light of opposite handedness does not cause any resonant effects. Furthermore, only chiral emitters of the matching handedness efficiently interact with such a chiral eigenmode, enabling the handedness-selective strength of light–matter coupling. The proposed system expands the set of tools available for investigations of chiral matter and opens the door to studies of a chiral electromagnetic vacuum.

Chiral Water-Soluble Molecular Capsules With Amphiphilic Interiors.

We present the synthesis of new chiral water-soluble dimeric capsules by the multicomponent Mannich reaction between charged amino acids (glutamic acid or arginine), resorcinarene, and formaldehyde and by subsequent self-assembly. The zwitterionic character of the backbones enables electrostatic interactions between arms and induces self-assembly of dimeric capsules, namely, (L-ArgR)2 and (L-GluR)2, in water with a wide range of pH, as demonstrated by NMR, diffusion coefficient measurement, and circular dichroism. The assembly/disassembly processes are fast on the NMR timescale. This mode of dimerization leaves side chains available for additional interactions and creates chiral cavities of mixed hydrophobic/hydrophilic character. According to this characteristic, capsules do not bind fully nonpolar or fully polar guests but effectively encapsulate a variety of chiral molecules with mixed polar/apolar characters (aliphatic and aromatic aldehydes, epoxides, alcohols, carboxylic acids, amines, and amino acids) with moderate strength. We also demonstrate the formation of heterocapsules (GluR) (ArgR) (homo- and heterochiral) that utilize additional interactions between charged acidic and basic side chains and have better encapsulation properties than those of the homodimers.

Simultaneous electrochemical recognition of tryptophan and penicillamine enantiomers based on MOF-modified β-CD

Chiral recognition is of significant importance in the fields of chemical asymmetric synthesis and biological pharmaceutical research. In this work, an electrochemical chiral sensor with two kinds of chiral sites (chiral cavity for β-cyclodextrin and chiral skeleton for Ca-sacc/MeOH) by electrooxidation β-cyclodextrin onto Ca-sacc/MeOH was built. The proposed multichiral β-CD@Ca-sacc/MeOH/GCE can be used for recognition of tryptophan and penicillamine enantiomers simultaneously with wide linear range, low detection limits value, high repeatability and stability within the available electrochemical window. The strategy for integration multichiral sources is crucial to construct novel chiral platforms for simultaneous recognition of multiple chiral compounds in complicated chiral systems.

Enantiomeric Water‐Soluble Octopus[3]arenes for Highly Enantioselective Recognition of Chiral Ammonium Salts in Water

AbstractStudy of enantioselective recognition in water by synthetic chiral macrocyclic receptors is undoubtedly of theoretical and practical significance, but it is a big challenge to achieve the enantioselective recognition with both high enantioselectivity and high affinity in water probably due to the deficiency of such water‐soluble macrocyclic receptors with stable chiral cavities. Herein, we report a new class of chiral macrocyclic arenes named octopus[3]arenes. The enantiomeric macrocycles are composed of three homochiral ethenoanthracene subunits, and they can be synthesized by two pathways and then easily converted into water‐soluble octopus[3]arenes P‐1 and M‐1. Notably, P‐1 and M‐1 with the rigid hexagonal structures and stable chiral hydrophobic cavities exhibit highly enantioselective recognition towards three pairs of chiral ammonium salts in water with the association constant up to 106 M−1 and the S/R selectivity up to 12.89.

Enantiomeric Water-Soluble Octopus[3]arenes for Highly Enantioselective Recognition of Chiral Ammonium Salts in Water.

Study of enantioselective recognition in water by synthetic chiral macrocyclic receptors is undoubtedly of theoretical and practical significance, but it is a big challenge to achieve the enantioselective recognition with both high enantioselectivity and high affinity in water probably due to the deficiency of such water-soluble macrocyclic receptors with stable chiral cavities. Herein, we report a new class of chiral macrocyclic arenes named octopus[3]arenes. The enantiomeric macrocycles are composed of three homochiral ethenoanthracene subunits, and they can be synthesized by two pathways and then easily converted into water-soluble octopus[3]arenes P-1 and M-1. Notably, P-1 and M-1 with the rigid hexagonal structures and stable chiral hydrophobic cavities exhibit highly enantioselective recognition towards three pairs of chiral ammonium salts in water with the association constant up to 106 M-1 and the S/R selectivity up to 12.89.