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The impact of optically active biomaterials on drug delivery remains a vital and hot topic. To reveal special advantages of optically active mesoporous silica nanoparticles in delivering drug in cells, optically active mesoporous silica nanoparticles deliver doxorubicin (DOX) with chiral behavior in cancer cells was studied. The present work focused on two types of optically active mesoporous silica nanoparticles named as levorotatory optically active mesoporous silica nanoparticles (LOA-MSNs) and dextrorotatory optically active mesoporous silica nanoparticles (DOA-MSNs) and examined their effects on cellular DOX delivery in cancer cells. The obtained LOA-MSNs and DOA-MSNs were regular spheres with particle diameters ranging from 200 to 250 nm, and their shell layer was filled with interlaced channels. Our results indicated that LOA-MSNs and DOA-MSNs did not exhibit cytotoxicity towards MCF-7 cells and B16 cells. The cytotoxicity of DOX-loaded LOA-MSNs and DOX-loaded DOA-MSNs were stronger than DOX owing to the synergistic retention and accumulation effect of nanoparticles. More importantly, DOX-loaded DOA-MSNs presented stronger cytotoxicity due to the higher synergistic retention and accumulation effect of DOA-MSNs. These findings suggest that DOA-MSNs with superior cellular delivery of DOX have great potential to advance the development of optical anti-tumor delivery system. [ABSTRACT FROM AUTHOR]

In the boundless landscape of scientific exploration, there exists a hidden, yet easily accessible, dimension that has often not only intrigued and puzzled researchers but also provided the key. This dimension is chirality, the property that describes the handedness of objects. The influence of chirality extends across diverse fields of study from the parity violation in electroweak interactions to the extremely large macroscopic systems such as galaxies. In this opinion piece, we will delve into the power of chirality in scientific exploration by examining some examples that, at different scales, demonstrate its role as a key to a better understanding of our world. Our goal is to incite researchers from all fields to seek, implement and utilize chirality in their research. Going this extra mile might be more rewarding than it seems at first glance, in particular with regard to the increasing demand for new functional materials in response to the contemporary scientific and technological challenges we are facing. This article is part of the theme issue 'Celebrating the 15th anniversary of the Royal Society Newton International Fellowship'. [ABSTRACT FROM AUTHOR]

In the search for novel polymeric molecules that could be used as electroactive materials, seven novel polyenaminones were prepared in high yields by the transaminative polymerization of resorcinol-derived bis-enaminones with m- and p-phenylenediamine and with 2,5-diaminohydroquinone. The obtained polymers show very low solubility in organic solvents and absorb UV light and visible light at wavelengths below 500 nm. All the obtained polymeric products were tested for redox activity in a Li battery setup. The 2,5-diaminohydroquinone-derived compound showed the best redox activity, with a maximum capacity of 86 mAh/g and relatively good capacity retention, thus confirming the hydroquinone group as the primary redox-active group. Other potential redox-active groups, such as resorcinol and conjugated carbonyls, showed limited activity, while variations in the phenylene groups and the substitution of phenolic groups in the resorcinol residue did not impact the electrochemical activity of the polymers. Their electrochemical properties, together with their previously established chemical recyclability, make polyenaminones promising scaffolds for the development of materials for sustainable energy storage applications. [ABSTRACT FROM AUTHOR]

Mono and bimetallic modified MCM-41(Mobil Composition of Matter No. 41): Zn-MCM (ZM), Zn/Co-MCM41 (ZCM), and Zn/Pd-MCM-41 (ZPM) molecular sieves were produced by a surfactant-assisted technique. The structural and textural features were examined through spectroscopic and analytical techniques. The XRD analysis indicated broadening of diffraction peaks and a shift towards higher 2-theta values in the metal-incorporated (M-MCM-41) samples, confirming the successful integration of metal atoms into the MCM-41 framework; it also highlighted the preservation of a hexagonal structure with reasonable regularity, emphasizing the influence of metal incorporation on the mesoporous architecture of MCM-41. N2 adsorption–desorption isotherms revealed type IV isotherms for all samples; the BET specific surface area decreased to 672.48, 667.90, and 562.50 m2/g in ZM, ZCM, and ZPM, respectively comparing to the unincorporated MCM-41 sample (1200 m2/g), indicating partial filling of mesopores by metal centers, as confirmed by TEM images. The diffuse reflectance spectra exhibited a noteworthy optical band gap reduction of MCM-41 (5.98 eV) upon the incorporation of Zn and Co/Zn ions, resulting in values of 5.86 and 5.24 eV, respectively, with refractive index values close to 2. Additional absorption bands energies are observed at 3.14, 3.18, and 1.70 eV in ZM, ZPM, and ZCM samples, respectively suggesting the suitability of the metal incorporated samples for the photocatalytic applications. The M-incorporated samples exhibited a decline in the transmission intensity accompanied by small shifts. The enhanced antimicrobial activity of the metal-incorporated samples, surpassing that of the pure MCM-41 against a variety of tested microorganisms, is attributed to the presence of incorporated metal species, which create a more acidic environment and substantially contribute to the heightened antimicrobial effectiveness. The ZM compound demonstrated potent inhibition against Bacillus cereus and Pseudomonas aeruginosa bacteria, displaying comparable efficacy to Ampicillin, as a reference antibiotic. Additionally, ZPM exhibited considerable inhibitory activity against Escherichia coli, surpassing the reference antibiotic and showing similar effectiveness against Bacillus cereus, Pseudomonas aeruginosa, and Salmonella typhimurium. [ABSTRACT FROM AUTHOR]

Chirality permeates every aspect of life's beauty. To foster a proper understanding of chirality among the public, this paper employs the differences between L- and D-tartaric acid enantiomers to design experiments for popularization of science: (1) Construction of molecular models of tartaric acid enantiomers; (2) Cultivation and observation of tartaric acid crystals; (3) Observation of the optical activity of tartaric acid solutions; (4) Recognition of chirality in tartaric acid molecules. These experiments range from basic to advanced, featuring simple operation, obvious phenomena, interactive communication, and have received positive feedback in the early stages of implementation. [ABSTRACT FROM AUTHOR]

Abstract The construction of covalent organic frameworks with special geometery and optical properties is of high interest, due to their unique physicochemical and biological properties. In this work, we report on a new method for the construction of triazine frameworks with defined topologies using coordination chemistry. Ball milling and wet chemical reactions between cyanuric chloride and melamine were directed in spatial arrangements and opposite optical activity. Cobalt was used as a directing agent to drive reactions into special morphologies, optical properties and biological activity. The enantiorecognition ability of triazine frameworks that was manifested in their activities against bacteria, demonstrated a new way for the construction of materials with specific interactions at biointerfaces.

The paper presents the photomechanical effect generated in new azo side-chain polyimides synthesized through a post-functionalization strategy involving the Mitsunobu reaction. Prepared azo polyimide foils were irradiated by a 405 nm diode-laser beam (intensity, I = 100 mW/cm2; polarization, Eǀǀx) for the generation of the photomechanical effect. Despite the low content of azo chromophore (substitution of the hydroxyl group was in the range of 7–35%) and thick cantilevers (thickness ~35 μm), bending angles were in the range of 30–40°. Thermal unbending was not observed for 12 months after turning off the excitation light. Our investigation showed that, despite the low content of azo chromophore, it is possible to achieve photodeformation under polarized light. To the best of our knowledge, this is the first example of the photomechanical response of azo pyridine polymers.

Enantiomeric discrimination plays a crucial role in the fields of analytical science and chemical biology. Herein, we achieve chiral recognition via angle-resolved polarized Raman scattering using a composite material consisting of an anisotropic two-dimensional material, ReSe2, and chiral Au nanoparticles (CAuNPs). A near-field effect is induced through the attachment of CAuNPs to ReSe2, in conjunction with modulation of polarized light, resulting in simultaneous angular polarization of ReSe2. This angular polarization was utilized for the chiral detection of tyrosine. Varying enantiomeric excess (ee) leads to inverse nonreciprocal angular deflections, which we propose arise from interactions between the chiral near-field and optical vectors modified by chiral molecules with distinct ee values. This phenomenon is primarily attributed to the optical spin Hall effect within the field, generating distinct vector deflections that can be utilized to discriminate between different enantiomers. Ultimately, we demonstrate selective identification of chiral substances by establishing a correlation between the optical inversion angle and ee value. This investigation presents an efficient and insightful approach for achieving rapid detection of chiral substances using rational optical devices. [ABSTRACT FROM AUTHOR]

Nonactin is a non‐enantiomorphous (S4 symmetric), optically active natural product with a specific rotation of zero in solutions at all frequencies and temperatures. All optically active, non‐enantiomorphous natural products have specific rotations of zero as a consequence of the spatial average of bisignate chiroptical (magnetoelectric or gyration) tensors with equal and opposite eigenvalues. Zeros that arise in the spatial average are distinct in principle, though not necessarily in practice, from zeros that arise in optical inactivity—chiroptical tensors with zero values for all elements as in centric molecules. Nonactin would be measurably optically active when oriented. The anisotropy of the optical activity of nonactin and its cation complexes, likewise S4 symmetric, are studied here by computation to emphasize the infelicitous linkage between optical activity and chirality. Computations show that changes in the conformation of the nonactin macrocycle upon complexation principally are responsible for diminishing the computed optical activity; the metals are incidental. [ABSTRACT FROM AUTHOR]

Dihydroquercetin (DHQ) is a representative of flavonoids that is available on the market as a food supplement and registered as an active pharmaceutical ingredient. The structure of this compound is characterized by the presence of two chiral centers in positions 2 and 3 of the pyranone ring. Current regulatory documentation on DHQ lacks quantitative analysis of the stereoisomers of this flavanonol. This poses potential risks for consumers of DHQ-based dietary supplements and developers of new drugs. This review was conducted to systematize data on the pharmacology of DHQ stereoisomers and the possible methods of controlling them in promising chiral drugs. We found that relying on literature data of polarimetry for the identification of DHQ stereoisomers is currently impossible due to these heterogeneities. NMR spectroscopy allows to distinguishing between trans- and c/s-DHQ using chemical shifts values. Only HPLC is currently characterized by sufficient enantioselectivity. Regarding pharmacology, the most active stereoisomer of DHQ should be identified, if the substituents in chiral centers both take part in binding with the biological target. The significant impact of stereochemical structure on the pharmacokinetics of DHQ isomers was reported. The question about these toxicity of these compounds remains open. The results of the conducted review of scientific literature indicate the necessity of revising the pharmacology of DHQ taking into account its stereoisomerism. [ABSTRACT FROM AUTHOR]

With the development of nanotechnology, it is found that the chiral semiconductor nanocrystals have vast potential applications in many different fields, such as biological labels, chiral analysis and detectors, enantioselective separation, gene editing, spin electronic devices, and so on. However, the study of their stability is rare. Here, we report the stability of chiral wurtzite CdSe quantum rods (QRs) and nanoplatelets (NPLs) with conventional chiral ligands of cysteine kept in an ambient atmosphere. The chiral QRs show specific stability in water solvents; however, that of the chiral NPLs is weak, with completely reverse chiroptical signs in just 90 min. The combination of experimental proofs and theoretical results reveals that the reversed optical activities come from the switch of electronic transition dipole moments of chiral CdSe surfaces. Our study helps to survey the construction of more stable chiral semiconductor nanomaterials, which is the key to improving their applications. [ABSTRACT FROM AUTHOR]

The surge in the incidence of skin cancer caused by UV exposure in Yemen served as the impetus for the current study. Fixed volumes and concentrations of both propolis aqueous extract and zinc salt solution were reacted to form zinc oxide (ZnO) nanoparticles at various temperatures (25, 35, 50, 65, 75, and 90 °C) and at a constant pH. The characteristics of the nanostructure and the degree of deformation that took place inside the nanoparticles were determined (for example, microstrain, stacking fault, surface stress, porosity, etc.). The optical parameters that affect the estimation of the blocking ultraviolet radiation parameters, such as the absorption coefficient, extinction coefficient, skin depth, refractive index, energy gap, Urbach energy, and optical conductivity, were calculated. The best results obtained in blocking ultraviolet radiation (A and B) were 81% and 75% for the sample that was prepared at 75 °C, respectively. Based on scientific methodology, empirical data, and exact equations, the results were interpreted within the nanoscale structure. [ABSTRACT FROM AUTHOR]

Chirality represents a fundamental characteristic inherent in nature, playing a pivotal role in the emergence of homochirality and the origin of life. While the principles of chirality in organic chemistry are well‐documented, the exploration of chirality within inorganic crystal structures continues to evolve. This ongoing development is primarily due to the diverse nature of crystal/amorphous structures in inorganic materials, along with the intricate symmetrical and asymmetrical relationships in the geometry of their constituent atoms. In this review, we commence with a summary of the foundational concept of chirality in molecules and solid states matters. This is followed by an introduction of structural chirality and electronic chirality in three‐dimensional and two‐dimensional inorganic materials. The construction of chirality in inorganic materials is classified into physical photolithography, wet‐chemistry method, self‐assembly, and chiral imprinting. Highlighting the significance of this field, we also summarize the research progress of chiral inorganic materials for applications in optical activity, enantiomeric recognition and chiral sensing, selective adsorption and enantioselective separation, asymmetric synthesis and catalysis, and chirality‐induced spin polarization. This review aims to provide a reference for ongoing research in chiral inorganic materials and potentially stimulate innovative strategies and novel applications in the realm of chirality. [ABSTRACT FROM AUTHOR]

The synthesis of bio‐derived cyclic carbonates is attracting a lot of attention as the incorporation of bio‐derived functionality into these compounds provides the opportunity to prepare previously unknown structures, whilst also improving their sustainability profiles. This study presents a facile preparation of diastereomerically pure bio‐derived cyclic carbonates displaying a range of optical rotation values. These compounds are obtained from glycidol, amino acids and CO2 in a facile two‐step approach. Initially, the diastereomerically pure amino acid functionalised epoxides are prepared through a robust Steglich esterification of enantiopure glycidol (R or S) and an amino acid (D or L). Thereafter, in a second step, cycloaddition of the epoxide with CO2 results in the retention of the initial stereochemistry of the epoxide, furnishing novel diastereomerically pure and optically active cyclic carbonate products. A DFT study has explained the basis of this observed retention of configuration for these compounds. Further, results from this DFT study also provide new mechanistic information concerning a co‐catalyst‐free cycloaddition reaction starting from glycidol when using the gallium‐catalyst, which is found to operate through metal‐ligand cooperativity. [ABSTRACT FROM AUTHOR]

It has been shown for the first time that the electric field can enhance the acousto-optic (AO) figure of merit due to the induced ellipticity of eigenwaves through the electro-gyration effect. As a result of the analysis, we have revealed that for the isotropic types of interaction, the increasing of the strength of the electric field results in the broadening of the full width at half maximum (FWHM) of the peak of the AO figure of merit, while almost does not affect the maximal value of this peak. The FWHM of the peak of the AO figure of merit tends to saturation with increasing electric field strength. For anisotropic types of diffraction, the peak of the AO figure of merit is not observed, but with increasing the electric field strength, the surface of the AO figure of merit is expanded. [ABSTRACT FROM AUTHOR]

Chirality is an essential geometric property unifying small molecules, biological macromolecules, inorganic nanomaterials, biological microparticles, and many other chemical structures. Numerous chirality measures have attempted to quantify this geometric property of mirror asymmetry and to correlate these measures with physical and chemical properties. However, their utility has been widely limited because these correlations have been largely notional. Furthermore, chirality measures also require prohibitively demanding computations, especially for chiral structures comprised of thousands of atoms. Acknowledging the fundamental problems with quantification of mirror asymmetry, including the ambiguity of sign‐variable pseudoscalar chirality measures, we revisit this subject because of the significance of quantifying chirality for quantitative biomimetics and describing the chirality of nanoscale materials that display chirality continuum and scale‐dependent mirror asymmetry. We apply the concept of torsion within the framework of differential geometry to the graph theoretical representation of chiral molecules and nanostructures to address some of the fundamental problems and practical limitations of other chirality measures. Chiral gold clusters and other chiral structures are used as models to elaborate a graph‐theoretical chirality (GTC) measure, demonstrating its applicability to chiral materials with different degrees of chirality at different scales. For specific cases, we show that GTC provides an adequate description of both the sign and magnitude of mirror asymmetry. The direct correlations with macroscopic properties, such as chiroptical spectra, are enhanced by using the hybrid chirality measures combining parameters from discrete mathematics and physics. Taking molecular helices as an example, we established a direct relation between GTC and optical activity, indicating that this chirality measure can be applied to chiral metamaterials and complex chiral constructs. [ABSTRACT FROM AUTHOR]

The paper presents the photomechanical effect generated in new azo side-chain polyimides synthesized through a post-functionalization strategy involving the Mitsunobu reaction. Prepared azo polyimide foils were irradiated by a 405 nm diode-laser beam (intensity, I = 100 mW/cm²; polarization, Eǀǀx) for the generation of the photomechanical effect. Despite the low content of azo chromophore (substitution of the hydroxyl group was in the range of 7–35%) and thick cantilevers (thickness ~35 µm), bending angles were in the range of 30–40°. Thermal unbending was not observed for 12 months after turning off the excitation light. Our investigation showed that, despite the low content of azo chromophore, it is possible to achieve photodeformation under polarized light. To the best of our knowledge, this is the first example of the photomechanical response of azo pyridine polymers. [ABSTRACT FROM AUTHOR]

Dye-doped cholesteric liquid crystals (DDCLCs) with a homeotropic initial state are more practical due to their lower power consumption and higher security. However, achieving the homeotropic initial state necessitates the use of long-pitch DDCLCs. The conventional formula for determining the planar (P) state transmittance of DDCLCs is inadequate for calculating the P state transmittance of long-pitch DDCLCs with pronounced optical activity. Therefore, in the experimental calculations and fitting, optical activity was introduced to amend the conventional formula and expand the calculation range to include visible wavelengths (400 nm-800 nm). Following numerous validations, a modified formula for calculating the P-state transmittance of DDCLCs was derived, which yields results closer to the actual values when optical activity is significant. This modification is of great significance in the design of long-pitch DDCLCs. [ABSTRACT FROM AUTHOR]

Dihydroquercetin (DHQ) is a representative of flavonoids that is available on the market as a food supplement and registered as an active pharmaceutical ingredient. The structure of this compound is characterized by the presence of two chiral centers in positions 2 and 3 of the pyranone ring. Current regulatory documentation on DHQ lacks quantitative analysis of the stereoisomers of this flavanonol. This poses potential risks for consumers of DHQ-based dietary supplements and developers of new drugs. This review was conducted to systematize data on the pharmacology of DHQ stereoisomers and the possible methods of controlling them in promising chiral drugs. We found that relying on literature data of polarimetry for the identification of DHQ stereoisomers is currently impossible due to these heterogeneities. NMR spectroscopy allows to distinguishing between trans- and cis-DHQ using chemical shifts values. Only HPLC is currently characterized by sufficient enantioselectivity. Regarding pharmacology, the most active stereoisomer of DHQ should be identified, if the substituents in chiral centers both take part in binding with the biological target. The significant impact of stereochemical structure on the pharmacokinetics of DHQ isomers was reported. The question about these toxicity of these compounds remains open. The results of the conducted review of scientific literature indicate the necessity of revising the pharmacology of DHQ taking into account its stereoisomerism.

In the search for novel polymeric molecules that could be used as electroactive materials, seven novel polyenaminones were prepared in high yields by the transaminative polymerization of resorcinol-derived bis-enaminones with m- and p-phenylenediamine and with 2,5-diaminohydroquinone. The obtained polymers show very low solubility in organic solvents and absorb UV light and visible light at wavelengths below 500 nm. All the obtained polymeric products were tested for redox activity in a Li battery setup. The 2,5-diaminohydroquinone-derived compound showed the best redox activity, with a maximum capacity of 86 mAh/g and relatively good capacity retention, thus confirming the hydroquinone group as the primary redox-active group. Other potential redox-active groups, such as resorcinol and conjugated carbonyls, showed limited activity, while variations in the phenylene groups and the substitution of phenolic groups in the resorcinol residue did not impact the electrochemical activity of the polymers. Their electrochemical properties, together with their previously established chemical recyclability, make polyenaminones promising scaffolds for the development of materials for sustainable energy storage applications.

Metal complexes of Co(II), Cu(II) and Ni(II) with the Schiff base ligand, 6,6ʹ-(([1,1ʹ-biphenyl]-4,4ʹ diylbis(azaneylylidene))bis(methaneylylidene))bis(2,4-dichlorophenol) (H2L) were synthesised. All synthesised compounds were identified and characterised. The conductivity measurements showed the non-electrolytic nature of all the complexes. The decomposition of all complexes ended with metal oxide. Octahedral geometries were proposed for all complexes. Photocatalytic degradation of methylene blue dye (MB) in the presence and absence of hydrogen peroxide was studied by using Co(II), Cu(II) and Ni(II) complexes as catalysts. Fluorescence studies have shown that the reported compounds can act as photoactive materials. Density functional theory was used to investigate the geometries of the ligand and its complexes. The adsorption of Co2+, Ni2+ and Cu2+ in an aqueous solution on H2L ligand under various conditions was studied. The optical properties of all complexes were studied. Antimicrobial activities of the ligand and its transition metal complexes were studied. The in-vitro cytotoxicity of ligand and its cobalt(II), nickel(II) and copper(II) complexes were evaluated towards the human Liver Carcinoma (HepG2) cell line and compared with standard cisplatin. [ABSTRACT FROM AUTHOR]

Multifunctional polarization controllers are highly desirable in numerous fields due to their potential applications. Although the emergence of metasurfaces provides a powerful platform for manipulating the polarization of electromagnetic waves, metasurfaces have not yet enabled multifunctional controllers. Here, this work demonstrates an effective strategy to design a multifunctional polarization controller through the integration of frequency and angular multiplexing. As an experimental proof, a non‐planar dual‐multiplexed metadevice composed of a chiral metagrating array and an anisotropic metasurface is fabricated by printed circuit board technology. The experiments show that at least five distinct functions, including ultra‐broadband linear‐to‐circular polarization conversion in 2.5–6.3 GHz, ultra‐broadband linear‐to‐linear polarization conversion in 6.6–11.0 GHz, strong optical activity between 11.4 and 12.2 GHz, giant linear and circular dichroism ≈5.96 and 12.97 GHz, respectively, can be accomplished by the proposed meta‐multiplexer. Hence, the proposed metadevice can act as high‐efficiency bifunctional waveplate, polarization rotator, linear polarizer, chiral metamirror, and so on, enabling more application flexibility. The concept of integrating multidimensional multiplexing proposed here will be of great benefit to the design of novel multifunctional polarization controllers. [ABSTRACT FROM AUTHOR]

Novel disulfinyl derivatives based on 3,4-dichloro-2(5H)-furanone, aliphatic dithiols, and monoterpene alcohols were synthesized. Chiral bis-thioethers in the molecules of which the dithiol fragment links two five-membered cycles at C4 atoms were obtained in the reactions of 5(S)-(l-menthyloxy)- and 5(S)-(l-bornyloxy)-2(5H)-furanones with ethane-1,2-dithiol and propane-1,3-dithiol in acetone in basic medium. The action of an excess of m-chloroperoxybenzoic acid (2.0–3.2 equiv.) on bis-thioethers led to the formation of the corresponding mono- and disulfoxides bearing l-menthol or l-borneol fragments at the 5th position of the lactone ring. The methods of column chromatography and fractional recrystallization were used for the isolation of individual products. The structure of the synthesized heterocycles was proved by IR and NMR spectroscopy, and their composition was confirmed by high-resolution mass spectrometry. The molecular structure of the three disulfoxides was characterized by X-ray diffraction analysis.

Enhanced chiral optical responses of metamaterials have widespread applications in chiral biosensor and polarization optics. Metamaterials with intrinsic chirality are commonly composed of complicated 3D structures, which leads to significant fabrication challenges. Recent works involving planar chiral metasurfaces have demonstrated chiral optical response by symmetry breaking, but the intrinsic optical chirality at normal incidence is usually weak. Here, a dielectric chiral metasurface is designed and fabricated, and its strong intrinsic optical chirality in visible spectrum is experimentally demonstrated. Particularly, giant optical activity with zero circular dichroism can be obtained, implying that linear polarization of the incident light passing through the metasurface can be rotated. A phenomenological model is proposed to explain the chiral optical response of the metasurface based on the superposition of two chiral optical resonances in opposite handedness. The multipole decomposition of the electric fields corroborates how the high‐order multipoles are related to the chiral optical response. These results enable the development of flat compact devices to manipulate the polarization of light flexibly. [ABSTRACT FROM AUTHOR]

We synthesized a fluorene‐bithiophene co‐polymer with chiral side chains (cPFT2) and investigated its chiroptical properties via synchotronradiation circular dichroism. We observed that thin films of the polymer display an intense circular dichroism (CD) upon annealing, which is of opposite handedness to the CD reported for similar polyfluorenes bearing the same enantiomeric chiral side chain. We then contrast the properties of this polymer with chiral side chain fluorene homopolymer (cPF) and observe large differences in their thin film morphology. Using photoluminescence spectroscopy, we uncover evidence of polymer chain bending in cPFT2, which is further supported by theoretical calculations, and propose an explanation for the observed inverted optical activity. [ABSTRACT FROM AUTHOR]

Linear polyynes of the formula C18H2 (symmetry D∞h) were bent in silico by progressively introducing CCC angles less than 180°. The bent structures (symmetry C2v) were then twisted by introducing torsion angles across the CCCC segments by as much as 60°. The gyration tensors of these 19 structures (linear, bent, and twisted) were computed by linear response methods. Bending is massively generative of optical activity in oriented structures, even achiral structures, whereas twisting in conjunction with bending, serves to linearize the molecules and diminish maximally observable optical activity. This computational exercise is intended to unbind the infelicitous linkage of optical activity and chirality, which is only meaningful in isotropic media. Although bent structures are not optically active in solution—the spatial average of the optical activity is necessarily zero—solution measurements that deliver the spatial averages are a special class of measurements, albeit the overwhelmingly most common chiroptical measurements, that prejudice our common understanding of how π‐conjugated structures generate gyration. Bending is far more effective than twisting at generating optical activity along some directions for oriented structures. The respective contributions from the transition electric dipole–magnetic dipole polarizability and the transition electric dipole–electric quadrupole polarizability are compared. [ABSTRACT FROM AUTHOR]

This work presents a novel approach for investigating symmetry‐breaking processes during crystallization using Mueller matrix polarimetry. By applying this method to the cooling process of NaClO3 solutions, we demonstrate its ability to capture not only the initial and final stages of crystallization but also the intermediate steps and dynamics of the process. This technique provides more comprehensive information and insights into the symmetry‐breaking mechanisms involved in crystal formation. Overall, this study highlights the potential of Mueller matrix polarimetry for in situ statistical measurements of the optical rotation and for monitoring the evolution of enantiomeric excesses. [ABSTRACT FROM AUTHOR]

The existence of an object, non-superimposable on its mirror image, constitutes the phenomenon of chirality. This phenomenon is often treated as a curiosity without broader practical consequences. This paper aims to show the significant implications of chirality for chemistry and biology. Chirality is inherent to all living organisms and is essential for their functioning. For instance, biomolecules are composed of chiral building blocks (amino acids, monosaccharides), which are chiral and occur predominantly with one sense of handedness (homochirality of life). The explanation of the evolution of the homochirality of life is therefore one of the important questions connected with the origin of life. The paper also shows why asymmetry with respect to mirror reflection is a general attribute of our world. Historical milestones in the scientific reflection on chirality are also presented, starting with the French crystallographers of the late 18th century, through the work of Pasteur, the fundamentals of organic stereochemistry postulated by van 't Hoff and Le Bel, the elucidation of a structure of monosaccharides by Fischer, and ending with the discovery of the absolute configuration of a molecule and the confirmation of parity violation of weak interaction. [ABSTRACT FROM AUTHOR]

Optical activity (polarization rotation of light) is one of the most desired features of chiral media, as it is important for many polarization‐related applications. However, in the THz region, chiral media with strong optical activity are not available in nature. Here, a chiral metamaterial (CMM) structure composed of pairs of vertical U‐shape resonators of "twisted" arms is studied, and it is revealed that it demonstrates large pure optical activity (i.e., optical activity associated with negligible transmitted wave ellipticity) in the low THz regime. The experimental data show polarization rotation up to 25° for an unmatched bandwidth of 1 THz (relative bandwidth 80%), from a 130 µm‐thickness structure, while theoretical optimizations show that the rotation can reach 45°. The enhanced chiral response of the structure is analyzed through an equivalent RLC circuit model, which also provides simple optimization rules for the enhancement of its chiral response. The proposed chiral design allows for easy fabrication via direct laser writing (DLW) and electroless metal plating, making the associated structures suitable candidates for polarization control applications. [ABSTRACT FROM AUTHOR]

We have synthesized and studied three new chiral substances as additives to a nematic liquid crystal. The difference in the optical activity and chemical structure of additive molecules results in the appearance of the chiral nematic phase and the change in both the compatibility of the mixture components and temperature range of the liquid crystal phase. The role of additives with fundamentally different structures and optical activities is shown. The increase in the TNI that is observed in mixtures with 4-[(2S)-(+)-2-Methylbutoxy]benzoic acid indicate the possibility of the increase in order caused by the formation of molecularly rigid and elongated dimers of the additive, which was confirmed using infrared spectra. The doping of the nematic liquid crystal with (2R)-(+)-2-[4-[2-Chloro-4-(4-hexylphenyl)phenyl]phenoxy]propanoic acid causes the lowering of TNI. The binol derivative S-(+)-6-[1-[2-(5-Carboxypentoxy)naphthalen-1-yl]naphthalen-2-yl] oxyhexanoic acid has the highest chirality among the additives used. One can explain the effects observed in terms of the role of size, shape, and compatibility with the nematic matrix as shown by the molecules that are used as additives. [ABSTRACT FROM AUTHOR]

The chiral‐induced spin selectivity (CISS) effect relates to the spin‐selective electron transport through chiral molecules; therefore, the chiral molecules act as spin filters. In past studies, correlation was found between the magnitude of the spin filtering and the intensity of the circular dichroism (CD) spectrum (the first Compton peak) of the molecules. Since the intensity of the CD peak relates to both the magnitude of the electric and magnetic dipole transitions, it was not clear which of these properties correlate with the CISS effect. This work aims at addressing this question. By studying the spin‐dependent conduction and the CD spectra of the thiol‐functionalized enantiopure binaphthalene (BINAP) and ternaphthalene (TERNAP), we found that both BINAP and TERNAP exhibit a similar spin polarization of 50%, despite the first Compton peak in TERNAP being almost twice as intense as the peak in BINAP. These results can be explained by the similar values of their anisotropy (or dissymmetry) factor, gabs, which is proportional to the magnetic transition dipole moment. Hence, we concluded that the CISS effect is proportional to the transition dipole moment in chiral molecules, namely, to the dissymmetry factor. [ABSTRACT FROM AUTHOR]

The purpose of this study is to modify all physicochemical properties of glycine–copper sulphate single crystals, such as crystal habits, molar mass, thermal stability, optical activity, and electrical properties. The novelty of this study is growth of glycine–copper sulphate single crystals doped by a low concentration of silver nanoparticles (SNPs) that improved both crystal habits and physicochemical properties. The originality of this work is that trace amounts of SNPs largely increased the crystal size. Crystals have molar stoichiometric formula [glycine]0.95, [CuSO4·5H2O]0.05 in the absence and presence of silver nanoparticles (SNPs) in different concentrations: 10 ppm, 20 ppm, and 30 ppm. The crystals’ names and abbreviations are: glycine–copper sulphate (GCS), glycine–copper sulphate doped by 10 ppm SNPs (GCSN1), glycine–copper sulphate doped by 20 ppm SNPs (GCSN2), and glycine–copper sulphate doped by 30 ppm SNPs (GCSN3). Dopant silver nanoparticles increased: crystallinity reflecting purity, transparency to UV-Vis. electromagnetic radiation, thermal stability, and melting point of glycine–copper sulphate single crystal. GCSN3 is a super conductor. High thermal conductivity of crystals ranging from 1.1 W·min−1·K−1 to 1.6 W·min−1·K−1 enabled attenuation of electromagnetic radiation and rapid heat dissipation due to good dielectric and polar properties. On rising temperature, AC electrical conductivity and dielectric properties of perfect crystal GCSN3 increased confirmed attenuation of thermal infrared radiation.

Little is known why illumination of linearly polarized continuous‐wave laser light can induce gyrotropy (optical rotatory power) and macroscopic circular/screwing deformations in amorphous As2S3. Gyrotropy appears through scattering and deflection of the incident light in combination with negative photoinduced birefringence. The gyrotropy could also trigger atomic motions under photoinduced fluidity, which produces macroscopic deformations. [ABSTRACT FROM AUTHOR]

We analyze anisotropic acousto-optic (AO) interactions of three possible acoustic eigenwaves with the incident and diffracted optical eigenwaves elliptically polarized due to optical activity effect in quartz crystals. Dependences of the effective elasto-optic (EO) coefficient and the AO figure of merit on the diffraction angle are obtained. We demonstrate that proper accounting for a nonzero ellipticity of the optical eigenwaves leads to nonzero values of some effective EO coefficients and a presence of the corresponding AO interactions of so-called types VII and VIII. We also reveal the effect of non-orthogonality of the acoustic waves on the effective EO coefficient and the AO figure of merit at the AO interactions of the types VII and VIII. The ellipticity of the optical eigenwaves manifests itself in peak-like angular maxima of the effective EO coefficient and the AO figure of merit for all the types of AO interactions under consideration. These maxima appear around the diffraction angles 0 and 180 deg that correspond to the collinear AO interaction between the circularly polarized optical waves propagating along the optic axis. The maximal values of the AO figure of merit in this case are respectively equal to 1.16×10-15, 0.36×10-15 and 0.48×10-15 s³/kg at the types VII, VIII and IX of AO interactions. Finally, we show that a deviation of the incidence angle from 90 deg at the interaction types VII and VIII leads to zeroing of the effective EO coefficient and the AO figure of merit. [ABSTRACT FROM AUTHOR]

The unique surface, optical and photocatalytic properties of nanomaterials based on various oxide nanoparticles have found wide application in wastewater treatment. In a number of modern scientific studies, bioactive catalysts based on TiO2, which exhibit redox activity in water purification, were considered. The presented structures based on titanium dioxide, formed in binary and ternary systems in the presence of silver and cerium with a different degree of crystallinity were obtained by the chemical precipitation method using titanium tetraisopropoxide (TTIP) as a precursor species. XRD data confirmed a homogeneous composition of powders formed in binary systems (anatase with clusters of Ag and CeO2) with CSR in the range of 9-20 nm. It was stated that in ternary systems, with an increase in the content of doping components, d spacing (101) of anatase's lattice shifted to the right, and the degree of tetragonality increased to 2.53. Raman results showed that the most intense band of Eg mode for doped samples TiO2 was shifted from 144 to 152 cm – 1 compared to anatase dependence on the noble metal concentration. The features of the silver-ceria and silver – titania interactions are connected with the size effects of both Ag and CeO2 particles, concentrations of oxygen vacancies in the ceria structure, and possible redox properties due to the interplay between Ag+/Ag0 and Ce3+/Ce4+ pair (PL) and a Schottky barrier between the metal and TiO2 and photoexcited electrons in the semiconductor are trapped by Ag nanoparticles. It was shown that the ternary composite TiO2 & CeO2 & Ag (2 wt. %) has improved photocatalytic activity due to the inclusion of CeO2 in the crystal lattice of anatase, which is confirmed by an increase in the degree of tetragonality of the lattice and prevention of oxidation of silver clusters on the surface of anatase under the influence of UV irradiation. These photocatalysts will be a perspective to the hydrogen synthesis technology. [ABSTRACT FROM AUTHOR]

Little is known why illumination of linearly polarized continuous‐wave laser light can induce gyrotropy (optical rotatory power) and macroscopic circular/screwing deformations in amorphous As2S3. Gyrotropy appears through scattering and deflection of the incident light in combination with negative photoinduced birefringence. The gyrotropy could also trigger atomic motions under photoinduced fluidity, which produces macroscopic deformations. [ABSTRACT FROM AUTHOR]

The diagonal components and the trace of two tensors which account for chiroptical response of the leucoindigo molecule C16H12N2O2 that is, static anapole magnetizability, and dynamic electric dipole‐magnetic dipole polarisability depending on the frequency of impinging light, are a function of the ϕ dihedral angle of torsion about the central CC bond, assumed to lie in the y direction of the coordinate system. They vanish for symmetry reasons at ϕ=0∘ and ϕ=180∘, corresponding respectively to C2v and C2h point group symmetries, that is, cis and trans conformers characterized by the presence of molecular symmetry planes. Nonetheless, diagonal components and average value of static anapole polarizability and optical rotation tensors vanish at ϕ=90∘, where leucondigo is unquestionably chiral from the geometrical viewpoint. Vanishing values of the average chiroptical properties have been observed also in the proximity of other ϕ angles. Attempts have been made to explain the occurrence of accidental zeros of chiroptical properties in terms of transition frequencies and scalar products appearing in the numerator of their quantum mechanical definitions. Within the electric dipole approximation, the presence of anomalous vanishing values of tensor components of anapole magnetizability and electric‐magnetic dipole polarizability is ascribed to physical achirality, arising from the lack of either toroidal or spiral electron flow along the x, y and z directions. [ABSTRACT FROM AUTHOR]

In this paper, density functional theory (DFT) is used to study the structure, electron and absorption properties of 6-Amino crystal in the pressure range of 0–300 GPa. The variations of the lattice constants, bond lengths and bond angles show that they undergo complex transformations under different pressures. More narrowly, the covalent bonds of the benzene ring and the uracil ring in the planar intramolecular structure are broken, and then the new covalent bonds between the adjacent intermolecular structure are reshaped at about 80, 100 and 160 GPa. The analysis results of band gap and DOS of 6-Amino indicate that the electronic properties of 6-Amino repeatedly transform from the semiconductor system into the metal phase at 80, 180 and 260 GPa. The absorption spectra show two important structural changes at 100 and 180 GPa, and present the high optical activity with the change of pressure. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQD) have received significant attention in recent years due to their potential applications in optics and sensing. In this study, the authors report on the first characterization of the optical activity and broad absorption spectrum covering from short‐wave ultraviolet, at 200 nm, to mid‐infrared, at 1600 nm, of CQD synthesized using the "low‐molecular‐weight alcohols electrochemical carbonization" method. The CQD are analyzed using spectroscopic techniques, optical activity in the infrared, and high‐resolution transmission electron microscopy. Results show a CQD size distribution of 5±3 nm and spherical morphology. The absorption spectra show increased absorption at both, high and low frequency. Additionally, the specific rotation of the CQD solution is significantly higher than that of pure ethanol, by three orders of magnitude. These findings suggest that CQD may have potential applications in polarized infrared filters and/or sensors due to their ability to rotate the polarization state of light at 1550 nm. The results of this study provide valuable insights into the optical properties of CQD and their potential for infiltration into hollow core photonic crystal fibers, making them a promising material for future research and development in the field of optics and sensing. [ABSTRACT FROM AUTHOR]

The purpose of this study is to modify all physicochemical properties of glycine–copper sulphate single crystals, such as crystal habits, molar mass, thermal stability, optical activity, and electrical properties. The novelty of this study is growth of glycine–copper sulphate single crystals doped by a low concentration of silver nanoparticles (SNPs) that improved both crystal habits and physicochemical properties. The originality of this work is that trace amounts of SNPs largely increased the crystal size. Crystals have molar stoichiometric formula [glycine]0.95, [CuSO4·5H2O]0.05 in the absence and presence of silver nanoparticles (SNPs) in different concentrations: 10 ppm, 20 ppm, and 30 ppm. The crystals' names and abbreviations are: glycine–copper sulphate (GCS), glycine–copper sulphate doped by 10 ppm SNPs (GCSN1), glycine–copper sulphate doped by 20 ppm SNPs (GCSN2), and glycine–copper sulphate doped by 30 ppm SNPs (GCSN3). Dopant silver nanoparticles increased: crystallinity reflecting purity, transparency to UV-Vis. electromagnetic radiation, thermal stability, and melting point of glycine–copper sulphate single crystal. GCSN3 is a super conductor. High thermal conductivity of crystals ranging from 1.1 W·min−1·K−1 to 1.6 W·min−1·K−1 enabled attenuation of electromagnetic radiation and rapid heat dissipation due to good dielectric and polar properties. On rising temperature, AC electrical conductivity and dielectric properties of perfect crystal GCSN3 increased confirmed attenuation of thermal infrared radiation. [ABSTRACT FROM AUTHOR]

We report on a spiral structure suitable for obtaining a large optical response. We constructed a structural mechanics model of the shape of the planar spiral structure when deformed and verified the effectiveness of the model. As a verification structure, we fabricated a large-scale spiral structure that operates in the GHz band by laser processing. Based on the GHz radio wave experiments, a more uniform deformation structure exhibited a higher cross-polarization component. This result suggests that uniform deformation structures can improve circular dichroism. Since large-scale devices enable speedy prototype verification, the obtained knowledge can be exported to miniaturized-scale devices, such as MEMS terahertz metamaterials. [ABSTRACT FROM AUTHOR]

Chiral plasmonic nanostructures have emerged as promising objects for numerous applications in nanophotonics, optoelectronics, biosensing, chemistry, and pharmacy. Here, we propose a novel method to induce strong chirality in achiral ensembles of gold nanoparticles via irradiation with circularly-polarized light of a picosecond Nd:YAG laser. Embedding of gold nanoparticles into a nanoporous silicate matrix leads to the formation of a racemic mixture of metal nanoparticles of different chirality that is enhanced by highly asymmetric dielectric environment of the nanoporous matrix. Then, illumination with intense circularly-polarized light selectively modifies the particles with the chirality defined by the handedness of the laser light, while their "enantiomers" survive the laser action almost unaffected. This novel modification of the spectral hole burning technique leads to the formation of an ensemble of plasmonic metal nanoparticles that demonstrates circular dichroism up to 100 mdeg. An unforeseen peculiarity of the chiral nanostructures obtained in this way is that 2D and 3D nanostructures contribute almost equally to the observed circular dichroism signals. Thus, the circular dichroism is neither even nor odd under reversal of direction of light propagation. These findings will help guide the development of a passive optical modulator and nanoplatform for enhanced chiral sensing and catalysis. [ABSTRACT FROM AUTHOR]

Plasmonic chirality of metamolecules attracts increasing attention because of the tunable circular dichroism (CD) and near‐field enhancement for chiral molecule detection. Although various mechanisms have been proposed to explain the plasmonic CD, the quantitative analysis of particles with sub‐wavelength dimensions remains to be refined. Unlike biomolecules and small particles for which only absorption effects are considered, both multipolar scattering and absorption of sub‐wavelength metamolecules need to be analyzed. Here, the extinction and CD of chiral metamolecules are experimentally measured, and the contribution of excited multipole moments is theoretically investigated via combining multipole scattering and optical theorem. It is found that for the low‐order resonance mode, the absorption dominates the CD signal. While for high‐order resonance modes, both scattering and absorption significantly influence the CD, and the high‐order electric quadrupole moment that is commonly ignored plays a crucial role. Moreover, the intrinsic mechanism of the chiral response is also intuitively explained with linear polarization analysis. The mechanism proposed here is not only applicable for biomolecules and tiny particles with low‐order resonance modes but also works well for sub‐wavelength particles with high‐order modes, where conventional mixed electric and magnetic polarizability mechanisms usually do not work very well. [ABSTRACT FROM AUTHOR]

2‐Amino[2.2]paracyclophane reacts with salicylaldehyde or 2‐hydroxyacetophenone to yield imines that then give access to a new series of boranils (8b–d) upon complexation with BF2. These novel boron‐containing compounds display both planar and axial chiralities and were examined experimentally and computationally. In particular, their photophysical and chiroptical properties were studied and compared to newly prepared, simpler boranils (9a–d) exhibiting axial chirality only. Less sophisticated chiral architectures were shown to demonstrate overall stronger circularly polarized luminescence (CPL) activity. [ABSTRACT FROM AUTHOR]