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Nanochannel membranes are promising materials for enantioselective sensing. However, it is difficult to make a compromise between the selectivity and permeability in traditional nanochannel membranes. Therefore, new types of nanochannel membranes with high enantioselectivity and excellent permeability should be explored for chiral analysis. Here, asymmetric catalysis strategy is reported for interfacial polymerization synthesis of chiral covalent‐organic framework (cCOF) nanochannel membrane for enantioselective sensing. Chiral phenylethylamine (S/R‐PEA) and 2,4,6‐triformylphloroglucinol (TP) are used to prepare chiral TP monomer. 4,4′,4″‐triaminotriphenylamine (TAPA) is then condensed with chiral TP to obtain cCOF nanochannel membrane via a C═N Schiff‐base reaction. The molar ratio of TP to S/R‐PEA is adjusted so that S/R‐PEA is bound to the aldehyde only or both the aldehyde and hydroxyl groups on TP to obtain chiral‐induced COF (cCOF‐1) or both chiral‐induced and modified COF (cCOF‐2) nanochannel membrane, respectively. The prepared cCOF‐2 nanochannel membrane showed two times more selectivity for limonene enantiomers than cCOF‐1 nanochannel membrane. Furthermore, cCOF‐2 nanochannel platform exhibited excellent sensing performance for other chiral molecules such as limonene, propanediol, methylbutyric acid, ibuprofen, and naproxen (limits of detection of 19–42 ng L−1, enantiomer excess of 63.6–86.3%). This work provides a promising way to develop cCOF‐based nanochannel enantioselective sensor. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Sensing the chirality of molecules is of great importance to fields such as enantioselective synthesis, pharmaceutical industry, and biomedicine. Plasmonic nanoparticles are ideal candidates for molecular sensing due to their inherent plasmonic properties that significantly enhance their sensitivity to surrounding molecules. Developing plasmonic nanoparticle‐molecule complexes for chirality sensing has drawn enormous attention in recent years due to their intriguing properties and potential applications. Thus, in this review, we believe it is timely to circumnavigate the rational design of plasmonic nanoparticle‐molecule complexes and widen the scope of their emerging applications in chirality sensing. First, we present different fundamental mechanisms for plasmon‐based chirality that are built on the system of plasmonic nanoparticle‐molecule complexes. Second, we review the typical applications of plasmonic nanoparticle‐molecule complexes in chirality sensing. Third, we discuss the emerging biomedical applications that the plasmon‐based chirality has attracted enormous interest. Finally, we provide an outlook on the challenges and opportunities in the field of plasmonic approaches for chirality sensing. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Sensing the chirality of molecules is of great importance to fields such as enantioselective synthesis, pharmaceutical industry, and biomedicine. Plasmonic nanoparticles are ideal candidates for molecular sensing due to their inherent plasmonic properties that significantly enhance their sensitivity to surrounding molecules. Developing plasmonic nanoparticle‐molecule complexes for chirality sensing has drawn enormous attention in recent years due to their intriguing properties and potential applications. Thus, in this review, we believe it is timely to circumnavigate the rational design of plasmonic nanoparticle‐molecule complexes and widen the scope of their emerging applications in chirality sensing. First, we present different fundamental mechanisms for plasmon‐based chirality that are built on the system of plasmonic nanoparticle‐molecule complexes. Second, we review the typical applications of plasmonic nanoparticle‐molecule complexes in chirality sensing. Third, we discuss the emerging biomedical applications that the plasmon‐based chirality has attracted enormous interest. Finally, we provide an outlook on the challenges and opportunities in the field of plasmonic approaches for chirality sensing. [ABSTRACT FROM AUTHOR]

Chirality distinguishing of biomolecules has attracted much attention in numerous fields. When detecting the chirality of molecules based on the optical rotation characteristics, the detection accuracy of specific rotation is closely related to solvent properties. Herein, taking amino acids as an example, in the case of changing the type, potential of hydrogen value, and concentration of solvents, respectively, the specific rotation is measured using spin Hall effect of light based on weak measurement. The results indicate that the specific rotation values of chiral molecules are different in different types of solvents. When phosphate buffered saline is used as the solvent, the detection sensitivity of chiral molecules is higher under alkaline conditions. When the pH value is fixed, the detection performance under the solvent concentration of 0.1 m is better than that of 0.01 or 0.001 m. The study shows that the solvent properties affect the specific rotation detection of chiral molecular solutions. Proper solvent properties can improve its accuracy, which is of great significance to promote the sensitivity of chiral discrimination. [ABSTRACT FROM AUTHOR]

Expanded helicenes are expected to show enhanced chiroptical properties as compared to the classical helicenes but the synthesis is very challenging. Herein, we report the facile synthesis of a series of expanded helicenes Hn (n=1–4) containing 11, 19, 27 and 35 cata‐fused benzene rings through Suzuki coupling‐based oligomerization followed by Bi(OTf)3‐mediated regioselective cyclization of vinyl ethers. Their structures were determined by X‐ray crystallographic analysis. Enantiopure H2, H3, and H4 can be isolated by chiral HPLC and they all exhibit strong chiroptical responses with high absorption dissymmetry factor (|gabs|) values (0.020 for H2, 0.021 for H3, and 0.021–0.024 for H4). [ABSTRACT FROM AUTHOR]

Unconventional superconductivity was realized in systems comprising a monolayer of magnetic adatoms adsorbed on conventional superconductors, forming Shiba‐bands. Another approach to induce unconventional superconductivity and 2D Shiba‐bands was recently introduced, namely, by adsorbing chiral molecules (ChMs) on conventional superconductors, which act in a similar way to magnetic impurities as verified by conductance spectroscopy. However, the fundamental effect ChMs have on the strength of superconductivity has not yet been directly observed and mapped. In this work, local magnetic susceptometry is applied on heterostructures comprising islands of ChMs (α‐helix L‐polyalanine) monolayers adsorbed on Nb. It is found that the ChMs alter the superconducting landscape, resulting in spatially‐modulated weaker superconductivity. Surprisingly, the reduced diamagnetic response is located along the perimeter of the islands with respect to both their interior and the bare Nb. The authors suggest that topological edge‐states forming at the edges are the source of the reduced superconductivity, akin to the case of magnetic islands. The results pave new paths for the realization of topological‐superconductivity‐based devices with changing order parameter. [ABSTRACT FROM AUTHOR]

The design and characterization of spatiotemporal nano‐/micro‐structural arrangement that enable real‐time and wide‐spectrum molecular analysis is reported and demonestrated in new horizons of biomedical applications, such as wearable‐spectrometry, ultra‐fast and onsite biopsy‐decision‐making for intraoperative surgical oncology, chiral‐drug identification, etc. The spatiotemporal sesning arrangement is achieved by scalable, binder‐free, functionalized hybrid spin‐sensitive (<↑| or <↓|) graphene‐ink printed sensing layers on free‐standing films made of porous, fibrous, and naturally helical cellulose networks in hierarchically stacked geometrical configuration (HSGC). The HSGC operates according to a time‐space‐resolved architecture that modulate the mass‐transfer rate for separation, eluation and detection of each individual compound within a mixture of the like, hereby providing a mass spectrogram. The HSGC could be used for a wide range of applictions, including fast and real‐time spectrogram generator of volatile organic compounds during liquid‐biopsy, without the need of any immunochemistry‐staining and complex power‐hungry cryogenic machines; and wearable spectrometry that provide spectral signature of molecular profiles emiited from skin in the course of various dietry conditions. [ABSTRACT FROM AUTHOR]

Metasurface‐based sensors, with their planar compact structure and excellent sensing performance, have become one of the emerging technologies in metasurface and nanophotonics in recent years. In particular, chiral metasurfaces show unique advantages for chiral molecule detection and enantiomer identification. Herein, a scheme of dual‐mode sensing based on all‐dielectric terahertz metasurface via chiral and achiral spectroscopy is proposed. The proposed achiral meta‐atoms show great extrinsic chirality. The transmitted linearly polarized spectrum and the circular dichroism (CD) can be used as the sensing indicator under normal and oblique incidence of the terahertz waves, respectively. Among them, the working mode based on linear polarization spectrum only needs to measure the transmission spectrum once, which means wide applicability. The other mode using CD can eliminate the achiral terahertz absorption of the analyte through multiple measurements and has a higher signal‐to‐noise ratio. The results show that the maximum refractive index–frequency change rates of the two operating modes are −128.5 GHz/RIU and −124.7 GHz/RIU, respectively. In addition, there are two resonant peaks available in both working states, for both high‐precision and wide‐range refractive index detection. This new scheme is expected to be applied in industrial fields such as terahertz biochemical detection. [ABSTRACT FROM AUTHOR]

The unbiased, naked structures of tartaric acid, one of the most important organic compounds existing in nature and a candidate to be present in the interstellar medium, has been revealed in this work for the first time. Solid samples of its naturally occurring (R,R) enantiomer have been vaporized by laser ablation, expanded in a supersonic jet, and characterized by Fourier transform microwave spectroscopy. In the isolation conditions of the jet, we have discovered up to five different structures stabilized by intramolecular hydrogen‐bond networks dominated by O−H⋅⋅⋅O=C and O−H⋅⋅⋅O motifs extended along the entire molecule. These five forms, two with an extended (trans) disposition of the carbon chain and three with a bent (gauche) disposition, can serve as a basis to represent the shape of tartaric acid. This work also reports the first set of spectroscopy data that can be used to detect tartaric acid in the interstellar medium. [ABSTRACT FROM AUTHOR]

We report the ground state tunneling splittings (ΔE±) of a number of axially chiral molecules using the ring‐polymer instanton (RPI) method (J. Chem. Phys., 2011, 134, 054109). The list includes isotopomers of hydrogen dichalcogenides H2X2 (X = O, S, Se, Te, and Po), hydrogen thioperoxide HSOH and dichlorodisulfane S2Cl2. Ab initio electronic‐structure calculations have been performed on the level of second‐order Møller–Plesset perturbation (MP2) theory either with split‐valance basis sets or augmented correlation‐consistent basis sets on H, O, S, and Cl atoms. Energy‐consistent pseudopotential and corresponding triple zeta basis sets of the Stuttgart group are used on Se, Te, and Po atoms. The results are further improved using single point calculations performed at the coupled cluster level with iterative singles and doubles and perturbative triples amplitudes. When available for comparison, our computed values of ΔE± are found to lie within the same order of magnitude as values reported in the literature, although RPI also provides predictions for H2Po2 and S2Cl2, which have not previously been directly calculated. Since RPI is a single‐shot method which does not require detailed prior knowledge of the optimal tunneling path, it offers an effective way for estimating the tunneling dynamics of more complex chiral molecules, and especially those with small tunneling splittings. [ABSTRACT FROM AUTHOR]

At the moment, there are approx. 100 published papers investigating halohydrin dehalogenases from different aspects; enzymology, molecular biology and reactions they can catalyse. Unquestionably, these enzymes are of great importance and hold an immense potential due to the wide spectrum of different compounds that can be synthesized by their action. These compounds, such as chiral epoxides, β‐substituted alcohols, oxazolidinones etc. significantly enrich the chemist's toolbox and, moreover, open the possibility for the synthesis of even more complex compounds. Still, there are many unknowns, and it is the purpose of this work to demonstrate the possibilities and bottlenecks, in scientific sense, that could further help in broadening the applicative potential of these fascinating enzymes. [ABSTRACT FROM AUTHOR]

Optical chirality sensing has attracted a lot of interest due to its potential in high‐throughput screening in chirality analysis. A molecular sensor is required to convert the chirality of analytes into optical signals. Although many molecular sensors have been reported, sensors with wide substrate scope remain to be developed. Herein, we report that the amide naphthotube‐based chirality sensors have an unprecedented wide scope for chiroptical sensing of organic molecules. The substrates include, but are not limited to common organic products in asymmetric catalysis, chiral molecules with inert groups or remote functional groups from their chiral centers, natural products and their derivatives, and chiral drugs. The effective chirality sensing is based on biomimetic recognition in water and on effective chirality transfer through guest‐induced formation of a chiral conformation of the sensors. Furthermore, the sensors can be used in real‐time monitoring on reaction kinetics in water and in determining absolute configurations and ee values of the products in asymmetric catalysis. [ABSTRACT FROM AUTHOR]

Abstract: Chiral molecules, especially enantiomers and diastereomers of purity > 99 %, present a significant market share within the chemical, pharmaceutical, and flavor industries. Antisolvent precipitations, both batch and semicontinuous operations to serve the current trends in flow chemistry were demonstrated to be environmentally benign and efficient tools in achieving high optical purities. Although salts are known to be insoluble in supercritical CO2, instabilities of the nascent salts were detected and applied for increasing efficiency. Diastereomeric excess values of the crystalline products exceeded 99 % in maximum of three consecutive steps both by repeated resolution with half molar equivalent of the amine to the acid and by direct recrystallization of the salts. [ABSTRACT FROM AUTHOR]

Molecular electronics focuses on the application of molecular building blocks for the fabrication of nanoscale electronic devices. The molecules offer nanosized repeatable structures that are critical for electronic components. In this work, a monolayer of chiral molecules is used to mediate the proximity effect between Nb, which is a conventional superconductor, and graphene. The conductance spectra of an Nb/chiral-molecule monolayer/graphene device exhibit split peaks terminated by side dips at temperatures well below the critical temperature of Nb. Such features cannot be accounted for by conventional superconductivity but are compatible with the emergence of an anisotropic chiral p-wave triplet state. This scenario gains support by fitting the spectra to a corresponding theoretical model and by a unique dependence of the peak height on the direction of an applied magnetic field. In general, these results provide clear evidence for a proximity effect through organic molecules, particularly with chiral molecules that are known to support spinselective transport. As a result, the presented device architecture may be useful in both electronic and spintronic circuits. [ABSTRACT FROM AUTHOR]

Electron spin states play an important role in many chemical processes. Most spin-state studies require the application of a magnetic field. Recently it was found that the transport of electrons through chiral molecules also depends on their spin states and may also play a role in enantiorecognition. Electrochemistry is an important tool for studying spin-specific processes and enantioseparation of chiral molecules. A new device is presented, which serves as the working electrode in electrochemical cells and is capable of providing information on the correlation of spin selectivity and the electrochemical process. The device is based on the Hall effect and it eliminates the need to apply an external magnetic field. Spin-selective electron transfer through chiral molecules can be monitored and the relationship between the enantiorecognition process and the spin of electrons elucidated. [ABSTRACT FROM AUTHOR]

L-α-Amino esters were considered valuable chiral starting materials in the with trifluoroacetaldehyde (fluoral) ethyl hemiacetal to obtain new functionalized trifluoromethyl aldimines. Starting from these latter compounds, isovaleraldehyde was used in proline-catalyzed Mannich-type to give trifluoromethyl syn- or anti-γ-amino alcohols bearing the L-α-amino ester function, simply by changing the reaction temperature. Chirality 27:571- 575, 2015. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

A poly(4-bromoaniline) (PBA) film is electrochemically synthesized on a gold electrode for the recognition of amino acids enantiomers. Scanning electron microscopy measurements show that the porous PBA films are made up of nano-ribbons. At the PBA modified Au electrode differential pulse voltammograms of L- and D-glutamic acids not only have very different current densities, but also produce different waveforms, providing an intuitive way to differentiate the two chiral molecules. Similar results are obtained in analyzing L- and D-aspartic acids. Control experiments suggest that the observed sensing behavior arises from synergistic interactions between Au and the PBA film, where polymerization at the meta-position creates a steric structure needed for differentiating chiral molecules. [ABSTRACT FROM AUTHOR]

We introduce the explicit concept of parity‐violating potential energy hypersurfaces which govern the rotation–vibration tunneling dynamics as well as the time‐dependent parity violation in chiral molecules. Calculations are reported for sections of the hypersurfaces of H2O2 and H2S2 at various levels of electroweak quantum chemistry, including CIS‐RHF, CIS‐LR, and CASSCF‐LR. Important findings concern the observed increase of the parity‐violating potentials (Epv) with increasing bond lengths rOO and rSS, which is to some extent physical and partly a consequence of the only approximate electronic wavefunction and perturbational treatment, the confirmation of lines and surfaces of “accidentally” zero Epv at chiral geometries, and the absence of a precise, simple scaling law for observables such as the measurable parity‐violating energy difference between enantiomers ΔEpv. The latter is due to the complicated geometry dependent Epv, although a rough scaling on the order of Z(5±1) with nuclear charges of the two heavy centers can be confirmed. The results are discussed in relation to possible experiments on molecular parity violation. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 [ABSTRACT FROM AUTHOR]