Synthesis, Structure, and Optical Property of [6]Cyclo-1,2-naphthylene.

A one-pot procedure with cobalt-mediated oxidation of 2,2'-dilithio-1,1'-binaphthyl by ferrocenium salts afforded the chiral cyclic hexamer of naphthylene, [6]cyclo-1,2-naphthylene (1). The molecular structure of 1 was determined by single crystal X-ray crystallography and NMR analyses, revealing its cyclic structure with an approximate D3 symmetry. Compound 1 exhibits blue emission at 383 nm with high photoluminescence quantum yield of 97%, which can be attributed to its rigid twelve-membered ring structure. Optical resolution of 1 by chiral HPLC allowed for the evaluation of its chiroptical properties. Each enantiomer exhibits circular dichroism with complex Cotton effects, which are grouped into three positive or three negative couplets. Circularly polarized luminescence is observed at 383 nm with an anisotropy factor |glum| on the order of 10-4. The high photoluminescence quantum yield and the CPL properties of 1 indicate its potential application as a CPL emitter.

Chirality in Insecticide Design and Efficacy.

Chirality plays a crucial role in the design and efficacy of insecticides, significantly influencing their biological activity, selectivity, and environmental impact. Recent advancements in chiral insecticides have focused on enhancing their effectiveness, reducing toxicity to nontarget organisms, and improving environmental sustainability. This review provides a comprehensive overview of the current state of knowledge on chiral insecticides, including neonicotinoids, isoxazolines, and sulfiliminyls. We discuss the stereochemistry, synthetic development, mode of action, and environmental fate of these compounds. The review highlights the importance of chirality in optimizing insecticidal properties and underscores the need for continued research into novel chiral compounds and advanced synthesis technologies. By understanding the role of chirality, we can develop more effective and environmentally friendly insecticides for sustainable pest management.

Copper-Catalyzed Enantioselective Dehydro-Diels-Alder Reaction: Atom-Economical Synthesis of Axially Chiral Carbazoles.

The dehydro-Diels-Alder (DDA) reaction is a powerful method for the construction of aromatic compounds. However, the enantioselective DDA reaction has been rarely developed, probably due to the competitive thermal reaction. Herein, we report a copper-catalyzed enantioselective DDA reaction through vinyl cation pathway. The reaction leads to the atom-economical synthesis of axially chiral phenyl and indolyl carbazoles in generally excellent yields with good to excellent atroposelectivities. This methodology represents the first example of non-noble metal-catalyzed enantioselective DDA reaction. Notably, new chiral ligand and organocatalyst derived from the constructed axially chiral carbazole are demonstrated to be useful in asymmetric catalysis.

VCD Analysis of Axial Chirality in Synthetic Stereoisomeric Biaryl-Type bis-Isochroman Heterodimers with Isolated Blocks of Central and Axial Chirality.

Optically active heterodimeric 5,5'-linked bis-isochromans, containing a stereogenic ortho-trisubstituted biaryl axis and up to four chirality centers, were synthesized stereoselectively by using a Suzuki-Miyaura biaryl coupling reaction of optically active isochroman and 1-arylpropan-2-ol derivatives, providing the first access to synthetic biaryl-type isochroman dimers. Enantiomeric pairs and stereoisomers up to seven derivatives were prepared with four different substitution patterns, which enabled us to test how OR, ECD, and VCD measurements and DFT calculations can be used to determine parallel central and axial chirality elements in three isolated blocks of chirality. In contrast to natural penicisteckins A-D and related biaryls, the ECD spectra and OR data of (aS) and (aR) atropodiastereomers did not reflect the opposite axial chirality, but they were characteristic of the central chirality. The atropodiastereomers showed consistently near-mirror-image VCD curves, allowing the determination of axial chirality with the aid of DFT calculation or by comparison of characteristic VCD transitions.

Enantiomer Recognition by the Difference in Adsorption Rates on the Surfaces of Chiral Crystals.

The chirality of biopolymers remains one of the mysteries of Life. For such objects, the phenomenon of supramolecular chirality (SMC) is vital. Enantiomers can be recognized by the adsorption on surfaces with SMC. However, the mechanisms of such chiral recognition are still unknown. In this work, the adsorption kinetics of menthol test enantiomers on the surfaces of γ-glycine and NiSO4•6H2O chiral crystals was studied. It was found that the difference in adsorption was observed in nonequilibrium state more often than in equilibrium. If the enantioselectivity in equilibrium state was observed, the enantioselectivity coefficient α at nonequilibrium conditions was higher. The maximum α in nonequilibrium state was 2.44 for γ-glycine crystals and 2.12 for NiSO4•6H2O crystals. Even if no differences in adsorption were observed under adsorption-desorption equilibrium conditions, a significant enantioselectivity at nonequilibrium conditions was found. This has proved the possibility of chiral recognition on surfaces with SMC by the differences in adsorption rates. Such novel chiral recognition mechanism can provide enhanced enantioselectivity in adsorption, catalysis, chromatographic separation, and chemical sensing.

6-Methoxy-2-Naphthoate as a Standard Chromophore for Chiroptical Studies by Fluorescence-Detected Exciton-Coupled Circular Dichroism.

This study investigated the applicability of fluorescent chromophores for exciton-coupled circular dichroism (ECCD) exploiting fluorescence-detected circular dichroism (FDCD). FDCD had been previously reported useful in allowing the sensitive detection of ECCD in favorable conditions. However, fluorescence detection may prevent applications of the combined method especially when solutions are polarized in emission. Even without polarization of emission, FDCD deviates from circular dichroism (CD) in some cases when the fluorophore of interest interacts with nonfluorescent chromophore. Herein, it was confirmed that employing 6-methoxy-2-naphthoate always yielded interpretable exciton-coupled FDCD spectra even when coupling with nonfluorescent p-substituted benzoates. The 6-methoxy-2-naphthoate chromophore (6-MN) is prescribed in special cases when only a small amount of sample is available for determining the absolute stereochemistry by the CD exciton chirality method observed by FDCD.

Hybrid Anapole Induced Chirality in Metasurfaces.

The interaction between light and matter, particularly chirality, plays a pivotal role in modern science and technology. Typically, metasurfaces achieve chiro-optical effects by coupling electric and magnetic dipoles in specific orientations. In this work, the design and optimization of an asymmetric H-shaped metasurface is explored to induce hybrid anapole (HA) for optical activity. When the symmetry of the metasurface structure is disrupted, the design can simultaneously excite first-order and pseudo high-order HA under illumination with a specific circular polarization, both occurring within the same spectral regime. This results in high reflection for one circular polarization and a significant reduction in reflection for the orthogonal polarization, thereby exhibiting exceptional chiro-optical activity. Moreover, the HA-based chiral metasurface demonstrates strong polarization control capabilities, as verified by Stokes parameter analysis, revealing high birefringence and a pronounced dependence on the incident polarization angle. These results provide valuable insights for the design and optimization of HA metasurfaces for advanced optical applications and polarization control, paving the way for new developments in chiral nanophotonics.

Many-Body Models for Chirality-Induced Spin Selectivity in Electron Transfer.

We present the first microscopic model for the chirality-induced spin selectivity effect in electron-transfer, in which the internal degrees of freedom of the chiral bridge are explicitly included. By exactly solving this model on short chiral chains we demonstrate that a sizable spin polarization on the acceptor arises from the interplay of coherent and incoherent dynamics, with strong electron-electron correlations yielding many-body states on the bridge as crucial ingredients. Moreover, we include the coherent and incoherent dynamics induced by interactions with vibrational modes and show that they can play an important role in determining the long-time polarized state probed in experiments.

Magneto-Responsive Chiral Optical Materials: Flow-Induced Twisting of Cellulose Nanocrystals in Patterned Magnetic Fields.

Magnetic fields have been used to uniformly align the lyotropic chiral nematic (cholesteric) liquid crystalline (LC) phase of biopolymers to a global orientation and optical appearance. Here, we demonstrate that, in contrast, weak and patterned magnetic field gradients can create a complex optical appearance with the variable spatial local organization of needle-like magnetically decorated cellulose nanocrystals. The formation of optically patterned thin films with left- and right-handed chiral and achiral regions is observed and related to local magnetic gradient-driven vortices during LC suspension flow. We trace the localized flow directions of the magnetically decorated nanocrystals during evaporation-induced assembly, demonstrating how competing evaporation and field-induced localized flow affect the twisted organization within magnetically induced vortices. The simulations suggested that localized twisting inversion originates from the interplay between the direction and strength of the local-depth-related magnetic gradients and the receding front through peripheral magnetic gaps. We propose that this finding will lead to magnetically patterned photonic films.

Zwitterionic Amino-Acid-Derived Polyacrylamides with a Betaine Twist - Synthesis and Characterization.

Amino-acid-derived polyzwitterions and polybetaines (PBs) are two promising alternatives to non-ionic polymers, for example, to increase tumor permeability. In this study, amino-acid-derived polyzwitterions are synthesized and a strategy to quarternize the amine in the side chain functional group is developed to combine the advantages of both types. The functional monomer is polymerized via reversible addition-fragmentation chain-transfer polymerization for which a kinetic study is performed. Further, the impact of the permanent positive charge on amino-acid-derived polyzwitterions is studied based on two zwitterionic polymers obtained via post-polymerization modification (PPM) of Poly(N-acryloxysuccinimide) to allow good comparison between methylated and non-methylated polymers. Circular dichroism shows that the stereocenter remains intact during PPM. pH titration and ζ-potential measurements show that the methylated polymer has a negative ζ-potential over the measured pH range and, therefore, the polymer remains zwitterionic over a broader pH range than its non-methylated equivalent. Both polymers are well tolerated by mammalian cells up to concentrations of 1 mg mL-1. The study introduces a path to a new polymer class that combines the advantages of both PBs and amino-acid-derived polyzwitterions and highlights the impact a permanent charge has on the physiochemical properties.

On the Origin of Enantioselectivity in Chiral Zeolite Asymmetric Catalyst GTM-3: Host-Guest Transfer of Chirality.

Knowledge of how extra-large-pore chiral zeolite asymmetric catalysts based on the -ITV framework imprint their chirality during a catalytic reaction is crucial in order to spread the scope for the catalytic enantioselective production of chiral compounds of interest. In this work, we have carried out a combined experimental and computational study on the catalytic activity of antipode GTM-3 catalysts during the ring-opening of trans-stilbene oxide with 1-butanol. Identification of the enantiomers of all the chiral species unraveled a surprising catalytic behavior: these chiral catalysts promote the transformation of one enantiomer of trans-stilbene oxide in the corresponding unlike product (with inversion of configuration of the attacked C) via an SN2 mechanism, and at the same time, the transformation of the other enantiomer of trans-stilbene oxide via an SN1-like mechanism into the like (with retention of configuration) and secondary products (diphenylacetaldehyde via Meinwald rearrangement and derived products). A computational study based on DFT + D methods suggested a potential explanation for this catalytic behavior, associated with a different orientation of trans-stilbene oxide enantiomers bound on the Ge(T7) positions in d4r units, which is stabilized by the development of intraframework H-bonds between the interrupted T7OH adjacent positions characteristic of this framework. Calculations suggest that each enantiomer of trans-stilbene oxide follows a different reaction pathway, one favoring the SN2 route by addition of butanol from the opposite side to form unlike-products, while the different orientation of the antipode enantiomer disfavors such SN2 route mainly by steric repulsions and at the same time favors the reaction toward the SN1 mechanism to give like- and secondary-products. Our study suggests that the strong enantioselectivity of GTM-3 catalysts for this reaction is associated with the particular orientation adopted by the chiral reactants within the chiral nanospace provided by the -ITV framework, similarly to what occurs with enzymes, and such preferential orientation is directly controlled by the asymmetric cavities where the reaction takes place, by the particular features of the Ge active sites in adjacent interrupted positions and by the presence of several framework OH groups in the nearby nanospace that interact with guest species. The experimental observations and the reaction mechanism proposed suggest that GTM-3 catalysts prepared from the (1S,2S) enantiomer of the N,N-ethyl-methyl-pseudoephedrinium organic agent should be enriched in the P4332 enantiomorphic space group of the -ITV framework and GTM-3 prepared from the (1R,2R) enantiomer in the antipode P4132. Interestingly, resolution of the absolute configuration of GTM-3 materials from 3D-electron diffraction data has been accomplished and confirms such an assignment, giving an average 82% enantio-enrichment in the corresponding chiral polymorph. Structure-solution of the location of the chiral structure-directing agents indicates that the transfer of chirality from the molecular component to the zeolite polymorph is governed by the development of strong H-bonds between the molecular hydroxyl group and the interrupted T(7)OH framework positions.

Unveiling the Loss Mode Enabled Tunable Plasmonic Chirality at Flat Metal Surface.

Plasmonic chirality has garnered significant interest in the past decade due to its enhanced chiral light-matter interactions. Current methods for achieving plasmonic chirality often rely on complex nanostructures or metamaterials, which are hampered by intricate fabrication processes. In this work, we present an approach to generate plasmonic chiral structured surface plasmon polariton (s-SPP) fields on a single, flat metal surface, bypassing elaborate fabrication techniques. The plasmonic chiral s-SPP fields are excited by the superposition of multiple differently oriented transverse magnetic polarized plane waves. We demonstrate, both theoretically and experimentally, the flexible tuning of chiral plasmonic patterns by adjusting the symmetry and phase differences of the incident waves. This method provides a facile mean to optically tailor plasmonic chiral properties on a subwavelength scale, offering potential applications in sensing, enantioselective reactions, imaging, and reconfigurable chiral switches.

Amorphous Solid Dispersion Formation for Enhanced Release Performance of Racemic and Enantiopure Praziquantel.

Praziquantel (PZQ) is the treatment of choice for schistosomiasis, which affects more than 250 million people globally. Commercial tablets contain the crystalline racemic compound (RS-PZQ) which limits drug dissolution and oral bioavailability and can lead to unwanted side effects and poor patient compliance due to the presence of the S-enantiomer. While many approaches have been explored for improving PZQ's dissolution and oral bioavailability, studies focusing on investigating its release from amorphous solid dispersions (ASDs) have been limited. In this work, nucleation induction time experiments were performed to identify suitable polymers for preparing ASDs using RS-PZQ and R-PZQ, the therapeutically active enantiomer. Cellulose-based polymers, hydroxypropyl methylcellulose acetate succinate (HPMCAS, MF grade) and hydroxypropyl methylcellulose (HPMC, E5 LV grade), were the best crystallization inhibitors for RS-PZQ in aqueous media and were selected for ASD preparation using solvent evaporation (SE) and hot-melt extrusion (HME). ASDs prepared experimentally were subjected to X-ray powder diffraction to verify their amorphous nature and a selected number of ASDs were monitored and found to remain physically stable following several months of storage under accelerated-stability testing conditions. SE HPMCAS-MF ASDs of RS-PZQ and R-PZQ showed faster release than HPMC E5 LV ASDs and maintained good performance with an increase in drug loading (DL). HME ASDs of RS-PZQ formulated using HPMCAS-MF exhibited slightly enhanced release compared to that of SE ASDs. SE HPMCAS-MF ASDs showed a maximum release increase of the order of 6 times compared to generic and branded (Biltricide) PZQ tablets. More importantly, SE R-PZQ ASDs with HPMCAS-MF released the drug as effectively as RS-PZQ or better, depending on the DL used. These findings have significant implications for the development of commercial PZQ formulations comprised solely of the R-enantiomer, which can result in mitigation of the biopharmaceutical and compliance issues associated with current commercial tablets.

Stereoregular Poly(Phenyl Glycidyl Ethers): In Situ Formation of a Polyether Stereocomplex from a Racemic Monomer Mixture.

Polymer stereocomplex formation represents a promising research area as it can improve thermal and mechanical properties of co-crystallized polymer strands of opposite chirality. Polymers that form stereocomplexes commonly feature high stereoregularity and usually require sourcing from enantiopure monomer building blocks. Herein, we report the in situ polyether stereo-complex formation from racemic epoxide monomers, i.e., substituted methyl phenyl glycidyl ethers. The bio-renewable glycidyl ethers were explored in both enantio- and isoselective ring-opening polymerizations (ROPs), resulting in isotactic poly(phenyl glycidyl ether). While the enantio-selective ROP selectively resolves a single enantiomeric, isotactic polyether stereoisomer ([mm]P ≥ 78%), the isoselective ROP leads to the concurrent formation of both isotactic (R)- and (S)-poly(phenyl glycidyl ether) stereoisomers ([mm]P ≥ 92%) and thus results directly in a stereoisomer blend, which forms a stereocomplex. This is one of only a few polymer stereocomplexes generated directly during polymerization from a racemic monomer mixture. Stereo-complexes of the different poly(phenyl glycidyl ether)s show an increase in melting temperature of up to 76 °C, relative to the enantiopure parent polymers. The position of the methyl group at the phenyl ring determines both stereocomplex formation and the thermal properties of the resulting materials.

Graphene-Templated Achiral Hybrid Perovskite for Circularly Polarized Light Sensing.

This study points out the importance of the templating effect in hybrid organic-inorganic perovskite semiconductors grown on graphene. By combining two achiral materials, we report the formation of a chiral composite heterostructure with electronic band splitting. The effect is observed through circularly polarized light emission and detection in a graphene/α-CH(NH2)2PbI3 perovskite composite, at ambient temperature and without a magnetic field. We exploit the spin-charge conversion by introducing an unbalanced spin population through polarized light that gives rise to a spin photoconductive effect rationalized by Rashba-type coupling. The prepared composite heterostructure exhibits a circularly polarized photoluminescence anisotropy gCPL of ∼0.35 at ∼2.54 × 103 W cm-2 confocal power density of 532 nm excitation. A carefully engineered interface between the graphene and the perovskite thin film enhances the Rashba field and generates the built-in electric field responsible for photocurrent, yielding a photoresponsivity of ∼105 A W-1 under ∼0.08 µW cm-2 fluence of visible light photons. The maximum photocurrent anisotropy factor gph is ∼0.51 under ∼0.16 µW cm-2 irradiance. The work sheds light on the photophysical properties of graphene/perovskite composite heterostructures, finding them to be a promising candidate for developing miniaturized spin-photonic devices.

Two-Step Chirality Transfer to Twisted Assemblies: Synergistic Interplay of Chiral and Aggregation Interactions.

Chirality plays a pivotal role in both the origin of life and the self-assembly of materials. However, the governing principles behind chirality transfer in hierarchical self-assembly across multiple length scales remain elusive. Here, we propose a concise and versatile simulation strategy using the patchy particle chain model to investigate the self-assembly of rods interacting through chiral and aggregation interactions. We reveal that chiral interaction possessing an entropic nature, amplifies the fluctuations and twists in the alignment of rods, while aggregation interaction serves as a foundational platform for aggregation and assembly. When both interactions exhibit moderate absolute and relative values, their synergistic interplay facilitates the chirality transfer from rods to assemblies, resulting in the formation of chiral mesoscale ordered structures. Furthermore, we observe a two-step chirality transfer process by monitoring the formation kinetics of the twisted assemblies. This work not only provides a comprehensive insight into chirality transfer mechanisms, but also introduces a versatile mesoscale simulation framework for exploring the role of chirality in hierarchical self-assembly.

Considering the impact of the chirality of therapeutic nanoparticles on cancer therapy.

"Inadequate understanding of chirality has potentially disastrous consequences. "Genius on the left, madman on the right" is not an exaggerated verse in the field of chiral research, but a realistic warning…".

A new motile animal with implications for the evolution of axial polarity from the Ediacaran of South Australia.

Fossils of the Ediacara Biota preserve the oldest evidence for complex, macroscopic animals. Most are difficult to constrain phylogenetically, however, the presence of rare, derived groups suggests that many more fossils from this period represent extant groups than are currently appreciated. One approach to recognize such early animals is to instead focus on characteristics widespread in animals today, for example multicellularity, motility, and axial polarity. Here, we describe a new taxon, Quaestio simpsonorum gen. et sp. nov. from the Ediacaran of South Australia. Quaestio is reconstructed with a thin external membrane connecting more resilient tissues with anterior-posterior polarity, left-right asymmetry and tentative evidence for dorsoventral differentiation. Associated trace fossils indicate an epibenthic and motile lifestyle. Our results suggest that Quaestio was a motile eumetazoan with a body plan not previously recognized in the Ediacaran, including definitive evidence of chirality. This organization, combined with previous evidence for axial patterning in a variety of other Ediacara taxa, demonstrates that metazoan body plans were well established in the Precambrian.

Light- and Temperature-Controlled Hybridization, Chiral Induction and Handedness of Helical Foldamers.

Helical foldamers have attracted much attention over the last decades given their resemblance to certain biomacromolecules and their potential in domains as different as pharmaceutics, catalysis and photonics. Various research groups have successfully controlled the right- or left- handedness of these oligomers by introducing stereogenic centers through covalent or non-covalent chemistry. However, developing helical structures whose handedness can be reversibly switched remains a major challenge for chemists. To date, such an achievement has been reported with light-responsive single-stranded foldamers only. Herein, we demonstrate that grafting a unidirectional motor onto foldamer strands constitutes a relevant strategy to i) control the single or double helical state of a foldamer, ii) switch on the chiral induction process from the motor to the helical strands and iii) select the handedness of double helical structures through photochemical and thermal stimulations.

Light-Up Fluorescence and Circularly Polarized Luminescence in Achiral Interlocked Framework via Adaptive Lone Pair-π Interaction Confinement.

Interactions between lone pairs and aromatic π systems are significant across biology and self-assembled materials. Herein, employing an achiral confinement metal-organic framework (MOF) encapsulates guest molecules, it is successfully realized that lone pair (lp)-π interaction induces fluorescence "turn-on" and circularly polarized luminescence for the first time. The MOFs synthesized based on naphthalenediimide show nearly non-emissive, which can be light-up by introducing acetone or ester guests containing lone pairs-π interaction. Furthermore, the introduction of a series of lp-rich chiral esters induces supramolecular chirality as well as circularly polarized luminescence in achiral MOFs, while also observing chiral adaptability. This work first demonstrates the luminescence and chiral induction via lone pair electrons-π interactions, presenting a fresh paradigm for the advancement of chiroptical materials.