Chiral Configuration Research Articles

BINOL-Based Chiral Macrocycles and Cages.

Chirality, a fundamental principle in chemistry, biology, and medicine, is prevalent in nature and in organisms. Chiral molecules, such as DNA, RNA, and proteins, are crucial in biomolecular synthesis, as well as in the development of functional materials. Among these, 1,1'-binaphthyl-2,2'-diol (BINOL) stands out for its stable chiral configuration, versatile functionality, and commercial availability. BINOL is widely employed in asymmetric catalysis and chiral materials. This review mainly focuses on recent research over the past five years concerning the use of BINOL derivatives for constructing chiral macrocycles and cages. Their contributions to chiral luminescence, enantiomeric separation, transmembrane transport, and asymmetric catalysis were examined.

Determination of Limonene Chirality in Oils Obtained from Different Types of Citrus Waste Peels in Türkiye

Limonene constitutes a significant amount in citrus oils. It has a chiral structure and has two different optically active isomers, R-limonene and S-limonene, which are symmetrical to each other. Determining the chiral configurations of limonene plays an important role in determining the beneficial use areas of essential oils. Citrus oils are used in a wide variety of industrial areas, depending on their limonene content. This paper presents the analytical method optimization, validation, and chirality studies of limonene in the citrus oils acquired from different citrus waste peels in Türkiye. An inlet temperature of 250 °C and an injection volume of 2 µL were decided as the optimal conditions for the most accurate measurement of both limonenes in the citrus oil. This method produced results for linearity, sensitivity (LODs and LOQs), repeatability, and reproducibility that were acceptable within the scope of the validation studies. The chirality of limonene was investigated in twenty-six citrus oils (fifteen orange oils, six lemon oils, four mandarin oils, and one grapefruit oil) in Türkiye. While the content of R-limonene in orange oil varied between 56.39% and 72.85%, the content of S-limonene changed from 2.53% to 5.71%. Whereas the constituent of R-limonene in lemon oils ranged from 54.73% to 73.99%, the content of S-limonene varied between 3.78-4.79%. In mandarin oils, the content of R-limonene was determined to be 58.02% and 65.05%, while the content of S-limonene was found as 3.05% and 4.87%. In single grapefruit oil, R-limonene content was 60.69% and S-limonene content was 3.12%.

Synthesis of Planar Chiral Compounds Containing α-Amino Phosphonates for Antiplant Virus Applications against Potato Virus Y.

An unprecedented study of the application of planar chiral compounds in antiviral pesticide development is reported. A class of multifunctional planar chiral ferrocene derivatives bearing α-amino phosphonate moieties was synthesized. These compounds, exhibiting superior optical purities, were subsequently subjected to antiviral evaluations against the notable plant pathogen potato virus Y (PVY). The influence of the absolute configurations of the planar chiral compounds on their antiviral bioactivities was significant. A number of these enantiomerically enriched planar chiral molecules demonstrated superior anti-PVY activities. Specifically, compound (Sp, R)-9n displayed extraordinary curative activities against PVY, with a 50% maximal effective concentration (EC50) of 216.11 μg/mL, surpassing the efficacy of ningnanmycin (NNM, 272.74 μg/mL). The protective activities of compound (Sp, R)-9n had an EC50 value of 152.78 μg/mL, which was better than that of NNM (413.22 μg/mL). The molecular docking and defense enzyme activity tests were carried out using the planar chiral molecules bearing different absolute configurations to investigate the mechanism of their antiviral activities against PVY. (Sp, R)-9n, (Sp, R)-9o, and NMM all showed stronger affinities to the PVY-CP than the (Rp, S)-9n. Investigations into the mechanisms revealed that the planar chiral configurations of the compounds played pivotal roles in the interactions between the PVY-CP molecules and could augment the activities of the defense enzymes. This study contributes substantial insights into the role of planar chirality in defending plants against viral infections.

Chiral dual-core emitters based-on through-space coupling for high-performance OLEDs with little efficiency roll-off

Through-space coupling (TSC) is the essential component of π-stacked systems and has promise in charge transport and electronic communication, which is of great significance for the construction of efficient and stable photoelectric devices. In this work, we demonstrate a chiral dual-core strategy for the design of high-performance organic circularly polarized emitters, which features of connecting two thermally activated delayed fluorescence (TADF) luminophores with chiral linkage that allows efficient TSC to occur. Using this strategy, a pair of dual-core enantiomers, R/S-DNKP, were designed and synthesized by linking two benzophenone derivatives with a 1,1′-bi-2-naphthol unit. Compared to the mono-core counterpart NKP, the dual-core emitters exhibited the photoluminescence quantum yields up to 94 %. Moreover, benefiting from their chiral helical folding configurations, the R/S-DNKP enantiomers exhibited the luminescence dissymmetry factor (|glum|) value of +2.7 × 10−3 and −2.6 × 10−3 in doped films. Notably, the electroluminescence devices based on the R/S-DNKP enantiomers achieved external quantum efficiency values of 21.5 % and 19.7 % with little roll-off. It is believed that this molecular design strategy will pave new routes for the development of high-performance chiral emitters for future organic photonic devices.

Chiral twisted molecular carbons: Synthesis, properties, and applications

AbstractIn recent years, the precisely controlled synthesis of chiral twisted molecular carbons has emerged as a forefront topic in the research of carbon materials. Molecular carbons refer to carbon nanomaterials synthesized with precision at the atomic level. Through rational design, rigid and stable chiral twisted structures can be synthesized. The exploration in the field of chiral twisted molecular carbons is key to fully understanding the various twisted configurations of carbon materials and delving into the relationship between structure design and functionality. This review explores chiral twisted configurations of carbon nanomaterials such as nanographene, carbon nanobelts, carbon nanosheets, graphdiyne, etc. It emphasizes the role of photocyclization, Scholl reaction, and Diels–Alder reactions in achieving precise chiral control and discusses a range of innovative design strategies. These strategies have led to the development of various twisted structures, such as helical, propeller, and Möbius strip configurations. The introduction of chirality, combined with the inherent exceptional optical properties of nanocarbon materials, has facilitated the creation of materials with superior chiroptical performances. This advancement is driving applications in fields such as optoelectronics and chiral optics.

BINOL‐based Chiral Macrocycles and Cages

Chirality, a fundamental principle in chemistry, biology, and medicine, is prevalent in nature and in organisms. Chiral molecules, such as DNA, RNA, and proteins, are crucial in biomolecular synthesis, as well as in the development of functional materials. Among these, 1,1´‐binaphthyl‐2,2´‐diol (BINOL) stands out for its stable chiral configuration, versatile functionality, and commercial availability. BINOL is widely employed in asymmetric catalysis and chiral materials. This review mainly focuses on recent research over the past five years concerning the use of BINOL derivatives for constructing chiral macrocycles and cages. Their contributions to chiral luminescence, enantiomeric separation, transmembrane transport, and asymmetric catalysis were examined.

Visual detection of chiral arginine enantiomer based on Fabry-Pérot resonator with BSA grafted polymer brush insulator as transducer

Molecular chiral recognition is significant in chemical, biological, and pharmacological research communities. Herein, we proposed a layered metal-insulator-metal (MIM) Fabry-Pérot resonator with bovine serum albumin (BSA) grafted polymer brush as the mid-responsive insulator layer for visual discrimination of chiral Arginine (Arg) enantiomer. The as-prepared MIM resonator exhibits distinguishing spectral shifts and apparent color change in response to Arg with different chiral configurations, which the naked eye can easily perceive. In addition, the proposed MIM resonator also shows the advantages of reasonable specificity, easy integrability, and extensive universality. Together with all these advantages, we believe the proposed visual detection strategy may open exciting avenues for detecting chiral molecules, especially in cost-efficient and point-of-care detection of chiral biomarkers for clinical disease diagnosis and therapy follow-up.

Excitation and dynamics of spin solitons in chiral magnetization configuration

This research paper presents systematic micromagnetic modeling of dynamic spin solitons carried by perpendicular magnetization component on a topologically preserved chiral sequence of uniform 360° in-plane domain walls with fixed boundaries in a strip. The long, narrow strip of a soft, magnetic thin film has a repeated in-plane magnetization pattern such that the local magnetization will rotate uniformly in a single chirality, either clockwise or counterclockwise, when moving along the strip in one direction at a constant speed. As spins in an excited soliton precess around its local magnetization field, the exchange interaction with the underlying chiral magnetization configuration yields a linear soliton motion with the direction determined by the handedness of precession and the underlying magnetization chirality. The local hyperbolic secant-like soliton profile holds its shape and energy when traveling without damping, continually changes its shape, and decays otherwise.

Collective Spin-Wave Dynamics in Gyroid Ferromagnetic Nanostructures.

Expanding upon the burgeoning discipline of magnonics, this research elucidates the intricate dynamics of spin waves (SWs) within three-dimensional nanoenvironments. It marks a shift from traditionally used planar systems to exploration of magnetization configurations and the resulting dynamics within 3D nanostructures. This study deploys micromagnetic simulations alongside ferromagnetic resonance measurements to scrutinize magnetic gyroids, periodic chiral configurations composed of chiral triple junctions with a period in nanoscale. Our findings uncover distinctive attributes intrinsic to the gyroid network, most notably the localization of collective SW excitations and the sensitivity of the gyroid's ferromagnetic response to the orientation of the static magnetic field, a correlation closely tied to the crystallographic alignment of the structure. Furthermore, we show that for the ferromagnetic resonance, multidomain gyroid films can be treated as a magnonic material with effective magnetization scaled by its filling factor. The implications of our research carry the potential for practical uses such as an effective, metamaterial-like substitute for ferromagnetic parts and lay the groundwork for radio frequency filters. The growing areas of 3D magnonics and spintronics present exciting opportunities to investigate and utilize gyroid nanostructures for signal processing purposes.

Design, Synthesis, Antifungal Activity, and Molecular Docking Studies of Novel Chiral Isoxazoline-Benzofuran-Sulfonamide Derivatives.

Succinate dehydrogenase (SDH) is one of the most important molecular targets for the development of novel fungicides. With the emerging problem of resistance in plant fungal pathogens, novel compounds with high fungicidal activity need to be developed, but the study of chiral pesticides for the inhibition of highly destructive plant pathogens has been rarely reported in recent years. Therefore, a series of novel chiral isoxazoline-benzofuran-sulfonamide derivatives were designed to investigate potential novel antifungal molecules. The chiral target compound 3a was cultured as a single crystal and confirmed using X-ray diffraction. All the target compounds were tested for antifungal activity, and compounds 3c, 3i, 3s, and 3r were found to have significant antifungal effects against S. sclerotiorum with EC50 values of 0.42 mg/L, 0.33 mg/L, 0.37 mg/L, and 0.40 mg/L, respectively, which were superior to the commercial fungicide fluopyram (EC50 = 0.47 mg/L). The IC50 value of compound 3i against the SDH of S. sclerotiorum was 0.63 mg/mL, which was further demonstrated by enzyme activity assays. Scanning electron microscopy showed that 3i had a significant inhibitory effect on S. sclerotiorum. In addition, the fluorescence quenching analysis assay indicated that compound 3i had a similar effect with the positive control fluopyram. Molecular docking exhibited that target compounds with chiral configuration had better affinity than racemic configuration, and 3i possessed stronger action than fluopyram, which was in keeping with the in vitro test results. These results would provide a basis and reference for the development of novel chiral fungicides.

Dithiocarbonate-Protected Au25 Nanorods of a Chiral D5 Configuration and NIR-II Phosphorescence.

Innovative surface-protecting ligands are in constant demand due to their crucial role in shaping the configuration, property, and application of gold nanoclusters. Here, the unprecedented O-ethyl dithiocarbonate (DTX)-stabilized atomically precise gold nanoclusters, [Au25(PPh3)10(DTX)5Cl2]2+ (Au25DTX-Cl) and [Au25(PPh3)10(DTX)5Br2]2+ (Au25DTX-Br), were synthesized and structurally characterized. The introduction of bidentate DTX ligands not only endowed the gold nanocluster with unique staggered Au25 nanorod configurations but also generated the symmetry breaking from the D5d geometry of the Au25 kernels to the chiral D5 configuration of the Au25 molecules. The chirality of Au25 nanorods was notably revealed through single-crystal X-ray diffraction, and chiral separation was induced by employing chiral DTX ligands. The staggered configurations of Au25 nanorods, as opposed to eclipsed ones, were responsible for the large red shift in the emission wavelengths, giving rise to a promising near-infrared II (NIR-II, >1000 nm) phosphorescence. Furthermore, their performances in photocatalytic sulfide oxidation and electrocatalytic hydrogen evolution reactions have been examined, and it has been demonstrated that the outstanding catalytic activity of gold nanoclusters is highly related to their stability.

Biomimetic Chiral Nanomaterials with Selective Catalysis Activity.

Chiral nanomaterials with unique chiral configurations and biocompatible ligands have been booming over the past decade for their interesting chiroptical effect, unique catalytical activity, and related bioapplications. The catalytic activity and selectivity of chiral nanomaterials have emerged as important topics, that can be potentially controlled and optimized by the rational biochemical design of nanomaterials. In this review, chiral nanomaterials synthesis, composition, and catalytic performances of different biohybrid chiral nanomaterials are discussed. The construction of chiral nanomaterials with multiscale chiral geometries along with the underlying principles for enhancing chiroptical responses are highlighted. Various biochemical approaches to regulate the selectivity and catalytic activity of chiral nanomaterials for biocatalysis are also summarized. Furthermore, attention is paid to specific chiral ligands, materials compositions, structure characteristics, and so on for introducing selective catalytic activities of representative chiral nanomaterials, with emphasis on substrates including small molecules, biological macromolecule, and in-site catalysis in living systems. Promising progress has also been emphasized in chiral nanomaterials featuring structural versatility and improved chiral responses that gave rise to unprecedented chances to utilize light for biocatalytic applications. In summary, the challenges, future trends, and prospects associated with chiral nanomaterials for catalysis are comprehensively proposed.

Modulation by Co (II) Ion of Optical Activities of L/D-glutathione (GSH)-modified Chiral Copper Nanoclusters for Sensitive Adenosine Triphosphate Detection.

Chiral nanoscale enantiomers exhibit different biological effects in living systems. However, their chirality effect on the detection sensitivity for chiral biological targets still needs to be explored. Here, we discovered that Co2+ can modulate the luminescence performance of L/D-glutathione (GSH)-modified copper nanoclusters (L/D-Cu NCs) and induce strong chiroptical activities as the asymmetric factor was enhanced 223-fold with their distribution regulating from the ultraviolet to visible region. One Co2+ coordinated with two GSH molecules that modified on the surface of Cu NCs in the way of CoN2O2. On this basis, dual-modal chiral and luminescent signals of Co2+ coordinated L/D-Cu NCs (L/D-Co-Cu NCs) were used to detect the chiral adenosine triphosphate (ATP) based on the competitive interaction between surficial GSH and ATP molecules with Co2+. The limits of detection of ATP obtained with fluorescence and circular dichroism intensity were 9.15 μM and 15.75 nM for L-Co-Cu NCs, and 5.35 μM and 4.69 nM for D-Co-Cu NCs. This demonstrated that selecting suitable chiral configurations of nanoprobes effectively enhances detection sensitivity. This study presents not only a novel method to modulate and enhance the chiroptical activity of nanomaterials but also a unique perspective of chirality effects on the detection performances for bio-targets.

Modulation by Co (II) Ion of Optical Activities of L/D‐glutathione (GSH)‐modified Chiral Copper Nanoclusters for Sensitive Adenosine Triphosphate Detection

AbstractChiral nanoscale enantiomers exhibit different biological effects in living systems. However, their chirality effect on the detection sensitivity for chiral biological targets still needs to be explored. Here, we discovered that Co2+ can modulate the luminescence performance of L/D‐glutathione (GSH)‐modified copper nanoclusters (L/D−Cu NCs) and induce strong chiroptical activities as the asymmetric factor was enhanced 223‐fold with their distribution regulating from the ultraviolet to visible region. One Co2+ coordinated with two GSH molecules that modified on the surface of Cu NCs in the way of CoN2O2. On this basis, dual‐modal chiral and luminescent signals of Co2+ coordinated L/D−Cu NCs (L/D−Co−Cu NCs) were used to detect the chiral adenosine triphosphate (ATP) based on the competitive interaction between surficial GSH and ATP molecules with Co2+. The limits of detection of ATP obtained with fluorescence and circular dichroism intensity were 9.15 μM and 15.75 nM for L−Co−Cu NCs, and 5.35 μM and 4.69 nM for D−Co−Cu NCs. This demonstrated that selecting suitable chiral configurations of nanoprobes effectively enhances detection sensitivity. This study presents not only a novel method to modulate and enhance the chiroptical activity of nanomaterials but also a unique perspective of chirality effects on the detection performances for bio‐targets.

Effect of bundling on phonon transport in single-walled carbon nanotubes

Thermally conductive bulk materials composed of single-walled carbon nanotubes (SWCNTs), such as fibers and mats, are characterized by a complex network formed by entangled SWCNTs. The fundamental unit of this network is a bundle, in which SWCNTs are assembled through weak van der Waals interactions. Although the thermal conductivity of a bundle is conventionally described as the sum of the heat conduction in the constituent SWCNTs, recent experiments have demonstrated that bundling may reduce the high thermal conductivity of SWCNTs, which is counterintuitive considering the weak interactions between SWCNTs in a bundle. Herein, by performing spectral phonon transport analysis for bundles of SWCNTs with radii of approximately 3.4 Å, we explore the effect of the bundle size and chiral configuration on phonon transport in bundles. Results show that although the heat conduction properties of individual SWCNTs are maintained for bundles with a length of less than 1 μm around room temperature in both the ballistic and quasi-ballistic regimes, intertube interactions between constituent SWCNTs coupled with their structural low dimensionality may yield additional thermal resistance. In particular, the thermal conductivity of a bundle decreases when low-frequency phonons influenced by intertube interactions substantially contribute to the overall heat conduction, namely, either at low temperatures or for long bundles. Although the observed additional thermal resistance cannot fully explain the experimental results of reduced thermal conductivity, our findings on the effect of bundling can advance the understanding of thermal transport in bundles and the thermal management of SWCNT bulk materials.

Synthesis of methyl-substituted aza[7]helicene with enhanced configurational stability and chiroptical performance

As an important building block, aza[7]helicene (A7H) plays a crucial role in constructing chiral conjugated molecules. However, the poor configurational stability of A7H makes it easily racemize, thus limiting its applications in chiroptical materials. In this work, we design and synthesize tetramethyl-substituted aza[7]helicene (TMA7H) to improve the configurational stability. Experimental results demonstrate that the racemization energy barrier (at 25 ℃) is significantly enhanced from 29.5 kcal mol−1 for A7H to 41.0 kcal mol−1 for TMA7H, indicating the higher configurational stability of enantiopure TMA7H which can keep its chiral configuration even at high temperatures. For instance, at 150 ℃, the racemization half-life of TMA7H is determined as 4.2 × 103 h (about six months), which is three orders of magnitude longer than that of A7H (1.1 h). Furthermore, TMA7H exhibits stronger circular dichroism responses and circularly polarized luminescence with higher dissymmetry factors, making it a superior building block for chiroptical materials.

Anomalies and persistent order in the chiral Gross-Neveu model

We study the 2d chiral Gross-Neveu model at finite temperature T and chemical potential μ. The analysis is performed by relating the theory to a SU(N) × U(1) Wess-Zumino-Witten model with appropriate levels and global identifications necessary to keep track of the fermion spin structures. At μ = 0 we show that a certain ℤ2-valued ’t Hooft anomaly forbids the system to be trivially gapped when fermions are periodic along the thermal circle for any N and any T > 0. We also study the two-point function of a certain composite fermion operator which allows us to determine the remnants for T > 0 of the inhomogeneous chiral phase configuration found at T = 0 for any N and any μ. The inhomogeneous configuration decays exponentially at large distances for anti-periodic fermions while it persists for T > 0 and any μ for periodic fermions, as expected from anomaly considerations. A large N analysis confirms the above findings.

Altering Spin Distribution of Tb2Pc3 via Molecular Chirality Manipulation.

Manipulating the chirality of the spin-polarized electronic state is pivotal for understanding many unusual quantum spin phenomena, but it has not been achieved at the single-molecule level. Here, using scanning tunneling microscopy and spectroscopy (STM/STS), we successfully manipulate the chirality of spin distribution in a triple-decker single-molecule magnet tris(phthalocyaninato)bis(terbium(III)) (Tb2Pc3), which is evaporated on a Pb(111) substrate via molecular beam epitaxy. The otherwise achiral Tb2Pc3 becomes chiral after being embedded into the self-assembled monolayer films of bis(phthalocyaninato)terbium(III) (TbPc2). The chirality of the spin distribution in Tb2Pc3 is manifested via the spatial mapping of its Kondo resonance state from its ligand orbital. Our first-principles calculations revealed that the spin and molecular chirality are associated with a small rotation followed by a structural distortion of the top Pc, consistent with the experimental observation. By constructing tailored molecular clusters with the STM tip, a single Tb2Pc3 molecule can be manipulated among achiral and differently handed chiral configurations of spin distributions reversibly. This paves the way for designing chiral spin enantiomers for fundamental studies and developing functional spintronic devices.

Chiral Light in Twisted Fabry–Pérot Cavities

AbstractFundamental studies of the interaction of chiral light with chiral matter are important for the development of techniques that allow handedness‐selective optical detection of chiral organic molecules. One approach to achieve this goal is the creation of a Fabry–Pérot cavity that supports eigenmodes with a desired electromagnetic handedness. This paper theoretically studies chiral Fabry–Pérot cavities with mirrors comprising 1D photonic crystal slabs made of van der Waals As2S3, a material with one of the highest known in‐plane anisotropies. By utilizing the anisotropy provided by As2S3, Fabry–Pérot cavities with constitutional and configurational chiralities are designed. It is demonstrated that in cavities with constitutional chirality, electromagnetic modes of left or right handedness exist due to the chirality of both mirrors, often referred to as handedness preserving mirrors in the literature. At the same time, cavities with configurational chirality support modes of both handednesses due to the chiral morphology of the entire structure, set by the twist angle between the optical axes of the upper and lower non‐chiral anisotropic mirrors. The developed chiral Fabry–Pérot cavities can be tuned to any distance between the mirrors by properly twisting them, making such systems a prospective platform for the coupling of chiral light with chiral matter.

Kinetically Controlled Stereoselective Synthesis of 2-Oxo-2-aryl-1,3,2-dioxaphosphorinane Derivatives via a Palladium-Catalyzed Reaction.

Chiral phosphonate esters have been widely applied in the fields of organic chemistry, medicine, and photoelectric materials. However, it requires the challenging enantioselective synthesis of cyclic phosphonate esters with the desired chiral configuration. The two epimers of 2-oxo-2H-1,3,2-dioxaphosphorinane derivatives should have different reactivities in Pd-catalyzed coupling reactions, which could lead to an effective methodology for the asymmetric synthesis of 2-oxo-2-aryl-1,3,2-dioxaphosphorinane derivatives. A thorough investigation of the coupling reactions both computationally and experimentally led to the stereoselective synthesis of chiral cyclic phosphonate esters. The axial isomer of products can be obtained with both high diastereoselectivity and good chemical yields from the mixture of 2-oxo-2H-1,3,2-dioxaphosphorinane derivatives under kinetically controlled conditions.