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Erbium-doped SnO2 films and devices are fabricated on silicon substrates, and the 1.54 μm emission of erbium ions is realized via energy transfer from the SnO2 host. It is found that the luminescence intensity for SnO2:Er film can be enhanced, by increasing the optical activity and transition probability of Er3+ ions with fluorine codoping. Moreover, the device prepared by the fluorine codoped SnO2 film presents a low turn-on voltage of 1.6 V and an onset electric field of 0.18 MV/cm. The unpackaged device operated for 1028h in the atmosphere, then continued to function at 40 °C/30% RH during 1003 h, with less than 10% optical power attenuation. Through further optimizing the preparation process, the optimal device exhibits an optical power density of 38.5 μW/cm2 at 1.55 μm, due to the improved crystalline quality together with the number of sensitizers. This work demonstrates the practical application potential in silicon-based light sources from erbium-doped SnO2 devices. [ABSTRACT FROM AUTHOR]

In this Tutorial, we overview recent developments to break and manipulate electromagnetic nonreciprocity in two-dimensional (2D) materials without relying on magnetic fields. To this purpose, we provide a general conductivity model to describe gyrotropic metasurfaces that exhibit nonreciprocity through different physical mechanisms enabled by 2D materials, including optical pumping, drifting electrons, ferromagnetic monolayers, mechanical strain, and spatiotemporal modulation. We describe in detail the resulting systems, focusing on near-field phenomena, associated to nonreciprocal bulk and edge surface plasmon propagation, and on far-field responses, related to Faraday/Kerr rotation and optical dichroism of waves propagating in free-space. Additionally, we review and contextualize recent advancements in magnet-free nonreciprocal devices based on 2D materials, ranging from Faraday rotators and optical dichrosim, to plasmonic and photonic isolators, hyperlenses, and tunable optical traps. We conclude by providing our outlook for the future development of this technology and its potential applications in areas such as communications, sensing, wave generation, and spectroscopy, among others. [ABSTRACT FROM AUTHOR]

We report the development of a novel variant of cavity ringdown polarimetry using a continuous-wave laser operating at 532 nm for highly precise chiroptical activity and magnetometry measurements. The key methodology of the apparatus relies upon the external modulation of the laser frequency at the frequency splitting between non-degenerate left- and right-circularly polarized cavity modes. The method is demonstrated by the evaluation of the Verdet constants of crystalline CeF3 and fused silica, in addition to the observation of gas- and solution-phase optical rotations of selected chiral molecules. Specifically, optical rotations of (i) vapors of α-pinene and R-(+)-limonene, (ii) mutarotating D-glucose in water, and (iii) acidified L-histidine solutions are determined. The detection sensitivities for the gas- and solution-phase chiral activity measurements are ∼ 30 and ∼ 120 μdeg over a 30 s detection period per cavity round trip pass, respectively. Furthermore, the measured optical rotations for R-(+)-limonene are compared with computations performed using the TURBOMOLE quantum chemistry package. The experimentally observed optically rotatory dispersion of this cyclic monoterpene was thus rationalized via a consideration of its room temperature conformer distribution as determined by the aforementioned single-point energy calculations. [ABSTRACT FROM AUTHOR]

Core–shell gold–silver cuboidal nanoparticles were produced, with either concave or straight facets. Their incubation with a low concentration of chiral l-glutathione (GSH) biomolecules was found to produce near UV plasmonic extinction and induced circular dichroism (CD) peaks. The effect is sensitive to the silver shell thickness. The GSH molecules were found to cause redistribution of silver in the shell, removing silver atoms from edges/corners and re-depositing them at the nanocuboid facets, probably through some redox and complexation processes between the silver and thiol group of the GSH. Other thiolated chiral biomolecules (and drug molecules) did not show this effect. The emerging near UV surface plasmon resonance is a silver slab resonance, which might also possess some multipolar resonance nature. The concave-shaped nanocuboids exhibited stronger induced plasmonic CD relative to the nanocuboids with straight facets. [ABSTRACT FROM AUTHOR]

We present a numerical approach to magnetic optical rotation based on real-time time-dependent electronic-structure theory. Not relying on perturbation expansions in the magnetic field strength, the formulation allows us to test the range of validity of the linear relation between the rotation angle per unit path length and the magnetic field strength that was established empirically by Verdet 160 years ago. Results obtained from time-dependent coupled-cluster and time-dependent current density-functional theory are presented for the closed-shell molecules H2, HF, and CO in magnetic fields up to 55 kT at standard temperature and pressure conditions. We find that Verdet's linearity remains valid up to roughly 10–20 kT, above which significant deviations from linearity are observed. Among the three current density-functional approximations tested in this work, the current-dependent Tao–Perdew–Staroverov–Scuseria hybrid functional performs the best in comparison with time-dependent coupled-cluster singles and doubles results for the magnetic optical rotation. [ABSTRACT FROM AUTHOR]

In this work, expressions for the third-harmonic scattering optical activity (THS-OA) spectroscopic responses are derived by combining molecular quantum electrodynamics (QED) and response theory, allowing their computational implementation. The QED theory of THS-OA presented here is meant to be an extension of a previous study by Andrews [Symmetry 12, 1466 (2020)]. In particular, the THS-OA phenomena are described within the Power–Zienau–Woolley multipolar Hamiltonian by including the electric-dipole, magnetic-dipole, and electric-quadrupole interactions for the absorption as well as the emission processes between the dynamic electromagnetic field (the photons) and matter. Moreover, we derive the expressions for the differential scattering ratios as a function of the scattering angle defined by the wavevectors of the incident and scattered photons. We show how the pure and mixed second hyperpolarizabilities can be obtained in the framework of response theory as specific cases of a generic cubic response function, thus enabling the computational implementation of THS-OA spectroscopy. We prove the origin-independence of the theory for exact wavefunctions. Preliminary computations on a prototype chiral molecule (methyloxirane) are considered together with an analysis of the basis set convergence and of the origin-dependence. [ABSTRACT FROM AUTHOR]

In this work, the theory of the modified unit sphere representation (mUSR) has been proposed as a computational tool suitable for the three‐dimensional representation of the pure electric‐dipole [βλμν(−2ω;ω,ω)] as well as of the mixed electric‐dipole/magnetic‐dipole [ αJλμν(−2ω;ω,ω) and βJλμν(−2ω;ω,ω)] or electric‐dipole/electric‐quadrupole [ αKλμνo(−2ω;ω,ω) and βKλμνo(−2ω;ω,ω)] first hyperpolarizabilities. These five quantities are Cartesian tensors and they are responsible for the chiral signal in the chiroptical version of the hyper‐Rayleigh scattering (HRS) spectroscopy, namely the HRS optical activity (HRS‐OA) spectroscopy. For the first time, for each hyperpolarizability, alongside with the three‐dimensional representation of the whole (i.e., reducible) Cartesian tensors, the mUSRs are developed for each of the irreducible Cartesian tensors (ICTs) that constitute them. This scheme has been applied to a series of three (chiral) hexahelicene molecules containing different degrees of electron‐withdrawing (quinone) groups and characterized by the same (positive) handedness. For these molecules, the mUSR shows that, upon substitution, the most remarkable qualitative and semi‐quantitative (enhancement of the molecular responses) effects are obtained for the pure electric‐dipole and for the mixed electric‐dipole/magnetic‐dipole hyperpolarizabilities. [ABSTRACT FROM AUTHOR]

[Display omitted] Since the chiral emission of excited states is observed on carbon dots (CDs), exploration towards the design and synthesis of chiral CDs nanomaterials with circularly polarized luminescence (CPL) properties has been at a brisk pace. In this regard, the "host and guest" co-assembly strategy based on the combination of CDs and chiral templates has been of unique interest recently for its convenient operation, multicolor tunable CPL, and wide application of prepared CDs-composited materials in optoelectronic devices and information encryption. However, the existing chiral templates that match perfectly with chiral CDs exhibiting optical activity both in ground and excited states are rather scarce. In this work, we synthesize the chiral CDs that could induce the spontaneous supramolecular self-assembly of N-(9-fluorenylmethox-ycarbonyl) (Fmoc)-protected glutamic acid to form chiral hydrogels with helical nanostructure. The co-assembled hydrogels show powerful chiral template function, which not only enable chiral CDs with a luminescence dissymmetry factor (g lum) up to 10-2, but also have universal chiral transfer to inserted dye molecules, realizing full-color CPL and Förster resonance energy transfer (FRET) CPL as well as the distinction between left and right circularly polarized light. This CPL-active template based on chiral CDs enriches the design scenario of chiral functionalized nanomaterials. [ABSTRACT FROM AUTHOR]

Circularly polarized light is previously shown as a chiral bias to enable the synthesis of chiral plasmonic nanomaterials through light‐matter interactions. The traditional approach for circularly polarized light generation relies on a “top‐down” approach by removing undesired light polarization through optics, which suffers from energy loss and compatibility issues. An alternative approach is to develop chiral phosphors that emit efficient circularly polarized luminescence (CPL). However, most materials fail to produce processable CPL with both high quantum yield and dissymmetry factors, let alone the synthesis of chiral nanomaterials. Herein, a liquid‐crystal‐templated framework is developed to assemble halide perovskite nanocrystals, CsPbX3 (X = Cl, Br, I), and achieved efficient CPL with the record‐high figure of merit (FM) for three primary colors (Red, Green, Blue). The fidelity of the CPL is further demonstrated in the synthesis of chiral gold nanoparticles, where a five‐fold increase in optical activity is achieved. [ABSTRACT FROM AUTHOR]

Developing highly sensitive and selective detection methods is crucial for environmental and healthcare monitoring. In this study, the chiral and fluorescent signals of L-glutathione-modified gold nanoclusters (L-GSH-Au NCs) were discovered to be responsive to Co2+, which displayed linear correlations with the concentration changes of Co2+. Notably, the chiral signal was more sensitive than the FL signal, whose limit of detection (LOD) was calculated to be 0.37 μM and 3.93 times lower than the LOD obtained with fluorescent signals. Moreover, the chiral signals exhibited unexpectedly high selectivity towards Co2+, effectively avoiding interference from other metal ions and biomolecules. Furthermore, the concentrations of Co2+ in various samples, such as Taihu water, tap water, bottled water, and animal serum, were accurately quantified using the chiral signals of L-GSH-Au NCs without complex pretreatment, with recoveries ranging between 95.64% and 103.22%. This study not only provides an innovative approach for Co2+ detection but also highlights the detection capabilities of chiral signals in complex environments. [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]

Gallium oxide (Ga2O3) can be crystallized in several polymorphs exhibiting different physical properties. In this work, polymorphic structures consisting of the cubic defective spinel (γ) film on the top of the monoclinic (β) substrate are fabricated by disorder‐induced ordering, known to be a practical way to stack these polymorphs together. Such bilayer structures are annealed to investigate optical properties and phase transformations. Specifically, photoluminescence and diffuse reflectance spectroscopy are combined with transmission electron microscopy, Rutherford backscattering/channeling spectrometry and X‐ray diffraction to monitor the evolutions. As a result, a two‐stage annealing kinetics is observed in γ/β Ga2O3 bilayers associated with the epitaxial γ‐to‐β regrowth at the interface at temperatures below 700 °C and a non‐planar γ‐to‐β phase transformation starting at higher temperatures. Thus, the present data enhance understanding of the polymorphism in Ga2O3, interconnecting the phase transformation kinetics with the evolution of the optical properties. [ABSTRACT FROM AUTHOR]

At present, the effects of environmental electromagnetic irradiation on the metabolism of organisms have attracted extensive attention, but the mechanism is still not clear. D-glucose plays an important role in the metabolism of organisms. In this work, the change in the optical rotation of D-glucose solution under an electrostatic field is measured experimentally, so as to explain the mechanism of the electric field-induced biological effect. The experimental results show that the electrostatic field can alter the optical rotation of D-glucose solution at different temperatures. Under the different strengths of electrostatic field, the specific rotation of D-glucose solution increases at different temperatures; the maximum increase can reach 2.07%, but the effect of temperature and electric field strength on the rotation increment is nonlinear and very complex. Further, it turns out that the proportion of α-D-glucose in solution increases by up to 3.25% under the electrostatic field, while the proportion of β-D-glucose decreases by as much as 1.75%. The experimental study confirms that electrostatic field can change the proportion of two conformation molecules (α and β-D-glucose) in D-glucose solution, which can provide a novel explanation for the mechanism of the electric field-induced biological effect. [ABSTRACT FROM AUTHOR]

Magneto‐optical activity is a significant way to achieve asymmetric transmission for spin photons. However, it is severely limited by the weak light‐matter interaction in the terahertz (THz) region. In this work, a magnetic Moiré grating (MMG) is constructed by sandwiching an Yttrium iron garnet (YIG) single crystal in a pair of twisted 2D subwavelength gratings. The twisted angle between two gratings introduces a strong geometric Moiré chirality related to the Moiré pattern. When an external magnetic field is applied to the YIG layer, three different symmetries of spacial mirror image, time reversal, and spin conjugation are broken simultaneously under the chiral coupling between magneto‐optical activity and Moiré chirality, leading to both the enhanced magneto‐optical chiral transmission and the nonreciprocal spin isolation. Under the magnetic field varying from −0.26 to +0.26 T in the experiment, the MMG achieves an active modulation of circular dichroism from 39 to −37.5 dB and optical activity from −35° to 30°. Moreover, the maximum spin isolation over 32.6 dB is also obtained near 0.5 THz. This mechanism provide a new way to realize independent manipulation and active modulation of THz spin photons more flexibly. [ABSTRACT FROM AUTHOR]

Herein we report on circularly polarized luminescence (CPL) emission originating from supramolecular chirality of organic microcrystals with a |glum| value up to 0.11. The microcrystals were prepared from highly emissive difluoroboron β‐diketonate (BF2dbk) dyes R‐1 or S‐1 with chiral binaphthol (BINOL) skeletons. R‐1 and S‐1 exhibit undetectable CPL signals in solution but manifest intense CPL emission in their chiral microcrystals. The chiral superstructures induced by BINOL skeletons were confirmed by single‐crystal XRD analysis. Spectral analysis and theoretical calculations indicate that intermolecular electronic coupling, mediated by the asymmetric stacking in the chiral superstructures, effectively alters excited‐state electronic structures and facilitates electron transitions perpendicular to BF2bdk planes. The coupling increases cosθμ,m from 0.05 (monomer) to 0.86 (tetramer) and triggers intense optical activity of BF2bdk. The results demonstrate that optical activity of chromophores within assemblies can be regulated by both orientation and extent of intermolecular electronic couplings. [ABSTRACT FROM AUTHOR]

Dichroic dye‐doped liquid crystal (LC) films are extensively developed to mimic the polarization‐dependent coloration found in nature, demonstrating potential applications in various optical devices, like displays. However, despite their remarkable optical anisotropy and functional potential, achieving precise coloration, especially green hues, in dichroic dye‐based films remains challenging due to the inherently broad absorption bands of the dyes. In this study, a straightforward and effective platform is proposed to extend the color gamut of dichroic dye‐doped LC films by utilizing cholesteric liquid crystals (CLCs) as wavelength‐selective polarization modulators. CLCs induce continuous optical rotation across the visible spectrum, enabling modulation of the polarization state of transmitted light. By systematically analyzing the optical properties of CLC, red, and cyan dichroic film‐based trilayer systems, the study demonstrates that simultaneous wavelength‐ and polarization‐selective absorption significantly extends the color gamut beyond that of conventional dichroic films. The findings indicate that the strategic positioning and alignment direction of dichroic films allow for precise control over transmission colors, making it possible to achieve previously unattainable green hues and a wider range of color variations. [ABSTRACT FROM AUTHOR]

Polyallenes with appropriate pendants can form stable helices and exhibit significant optical activity. These helical polyallenes contain reactive double bonds that allow for further functionalization, making them a class of chiral functional materials with broad application prospects. This review article delves into the intricacies of synthesizing well‐defined helical polyallenes through controlled synthetic methodologies, including helix‐sense selective living polymerization, regioselective and asymmetric living polymerization, and one‐pot block copolymerization of allenes with aryl monomers. The systemically outlined characteristics of the resulting helical polyallenes and related copolymers are summarized include their unique chiroptical properties, stimuli‐responsiveness, helix‐induced chiral self‐assembly, and circularly polarized luminescence (CPL). Additionally, current challenges and future perspectives in the research of controlled synthesis, functionalities, and applications of helical polyallenes are discussed in detail. [ABSTRACT FROM AUTHOR]

To describe the optical activities of crystals, gyration tensors are necessary for all wavelengths of incident light. To date, few studies on direct calculations of gyration tensors from Bloch states have been conducted. Herein, a practical procedure to obtain gyration tensors of organic crystals is presented using the crystal orbital method. The extended Hückel method was adopted to evaluate the gyration tensors, epitomizing the one‐electron formulation. To confirm the validity of the formulation, the optical rotatory power of alanine and γ‐glycine was examined. The reproduced profiles of the optical rotatory power were consistent with the results of recent experiments. This is a general formulation of the one‐electron theory of optical activities for three‐dimensional crystals. In principle, the optical rotatory strength tensor is not invariant with translation. For systems with small unit cells, however, the formalism is quasi‐invariant with respect to translation. The quasi origin‐independent formalism is sufficiently substantial to be applicable to modern crystal optics. [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]

In the past decade, molybdenum ditelluride (MoTe2) has received significant attention from the scientific community due to its structural features and unique properties originate from them. In the current review, the properties, various preparation approaches, and versatile applications of MoTe2 are presented. The review provides a brief update on the state of our fundamental understanding of MoTe2 material and also discusses the issues that need to be resolved. To introduce MoTe2, we briefly summarize its structural, optoelectronic, magnetic, and mechanical properties in the beginning. Then, different preparation methods of MoTe2, such as exfoliation, laser treatment, deposition, hydrothermal, microwave, and molecular beam epitaxy, are included. The excellent electrical conductivity, strong optical activity, tunable bandgap, high sensitivity, and impressive stability make it an ideal contender for different applications, including energy storage, catalysis, sensors, solar cells, photodetectors, and transistors. The performance of MoTe2 in these applications is systematically introduced along with mechanistic insights. At the end of the article, the challenges and possible future directions are highlighted to further modify MoTe2 material for the numerous functionalities. Therefore, the availability of different phases and layer structures implies a potential for MoTe2 to lead an era of two‐dimensional materials that began from the exfoliation of graphene. [ABSTRACT FROM AUTHOR]

ABSTRACT Chirally pure enantiomers of differently protected 7‐azatryptophan derivatives (R‐3c, S‐3c, R‐3i, S‐3i, R‐3m, S‐3m, R‐3aa, and S‐3aa) were synthesized, which showed solvent‐dependent optical rotation. The obtained results not only exhibited changes in the values but also showed the variation in sign (− or +) with the different solvents studied. The change in optical rotation value was essentially attributed to the electron‐donating property, which can be correlated to the donor number of the solvents. There are two types of hydrogen bonds, intramolecular (i.e., form within the structure) and intermolecular (i.e., form with external groups such as solvents). These hydrogen bonds are responsible for the value and sign variations, and 1H NMR experiments were used to further characterize them. The NMR data suggested that hydrogen bond formation is occurring between the Fmoc NH group vicinal to the chiral center and donor group of the corresponding solvent. [ABSTRACT FROM AUTHOR]

ABSTRACT The design and setup of a novel and simple backscatter Raman optical activity (ROA) spectrometer with incident light circular polarization (ICP) is presented, constructed from commercially available components. Incident light polarization is controlled using a combination of waveplates, compensating for unwanted birefringence and beam offsets. Realignment of the spectra in post‐processing reduced artifacts caused by spatial offsets. Spurious signals from achiral solvents like toluene and water are almost completely removed. The setup was validated by measuring references samples, including α‐pinene, carvone, and glucose in aqueous solution. The spectra show very good agreement with previously published results. [ABSTRACT FROM AUTHOR]

Constructing organic composite materials through molecular recognition has emerged as an important theme in materials science. Here we report an ion‐pair recognition system involving the use of a propoxylated pillar[5]arene (PrP5) to modulate the solid‐state photophysical properties of dye trans‐4'‐(dimethylamino)‐N‐methyl‐4‐stilbazolium hexafluorophosphate (DMASP). Single crystal X‐ray diffraction analysis reveals that the dye guest DMASP is encapsulated by PrP5 to form a 2 : 1 host−guest complex 2PrP5⸧DMASP in the crystalline state. The macrocyclic skeleton of PrP5 imposes restrictions on the intramolecular motions of the dye guest, leading to a significant enhancement of its fluorescence emission. Additionally, within the 2PrP5⸧DMASP complex crystal structure, DMASP molecules are found to display two possible opposite orientations in the one‐dimensional channels formed by PrP5 molecules. This arrangement is believed to alter the overall solid‐state packing structure of DMASP, thereby activating its nonlinear optical activity. This work not only reports a novel ion‐pair molecular recognition system based on pillararenes but also provides valuable insights into the modulation of the crystalline state photophysical properties of organic dyes via cocrystal engineering. [ABSTRACT FROM AUTHOR]

The Ag + ions doped TiO 2 nanotube arrays fabricated on Ti mesh through an electrochemical anodization process, and n/n heterostructure formed by coating the TiO 2 nanotube array photoanode with an n-type stibnite (Sb 2 S 3) layer improve photoelectrochemical water splitting reaction by enhancing light harvesting and charge carrier separation. Sb 2 S 3 is chosen because of its suitable band gap position and strong visible light response. The Ag + ion incorporated TiO 2 nanotube array coated with Sb 2 S 3 exhibits a photocurrent density of 6.5 mA cm−2 vs. RHE, whereas bare TiO 2 nanotube array coated with Sb 2 S 3 and pristine TiO 2 nanotube array exhibit photocurrent densities of 3.6 and 0.27 mA cm−2, respectively, under the same conditions, which is nearly 1.8 and 24 times greater than the TiO 2 nanotube array coated with Sb 2 S 3 and pristine TiO 2 nanotube array photoanodes. The applied bias photon-to-current efficiency of Ag + ion incorporated TiO 2 nanotube array coated with Sb 2 S 3 is 3.6% and the improved Photoelectrochemical performance of Ag + ion doped TiO 2 nanotube array coated with Sb 2 S 3 is attributable to higher conductivity of TiO 2 nanotube array caused by increased oxygen vacancies and broad optical activity of Sb 2 S 3. The 1-dimensional TiO 2 nanotube array device structure in the Ti mesh improves charge separation and light harvesting while reducing photogenerated charge carrier recombination and the potential of this novel device structure for advanced energy conversion applications is highlighted in this study. [Display omitted] • Ag + ions doped TiO 2 nanotube array-Sb 2 S 3 Schottky-junction was fabricated on a porous titanium substrate. • The TiO 2 –Sb 2 S 3 device was tested for photoelectrochemical water splitting reaction. • Ag + doped TiO 2 –Sb 2 S 3 Schottky junction enhances light harvesting and charge carrier separation. • The potential of the novel PEC device for water splitting is highlighted. [ABSTRACT FROM AUTHOR]

Given the scientifically significant importance of studying the chirality of clusters, the challenges of synthesizing chiral clusters are progressively surmounted. However, the racemization of clusters is unavoidable, and it limits the development of their follow‐on chiral applications. To address this issue, chiral thiols are synthesized and used for the construction of high‐stability optically pure nanoclusters in this work. As a result, a pair of chiral nanoclusters, Au24Cd2(SR)14, is obtained with excellent stability under thermal, acidic, alkaline, oxidizing, and reducing environments. Unexpectedly, it can also maintain its optical activity with the introduction of Cu2+ ions and chiral ligand with opposite configuration. Structural relationship analysis indicates that the excellent stability is mainly dependent on the hierarchical assembly of the nanoclusters, in which the chiral assembly of chiral ligands (a new pattern of chiral arrangement of intramolecular ligands on the surface of clusters) may be a key factor. [ABSTRACT FROM AUTHOR]

Extensive efforts have been dedicated towards designing new organic materials that display solid-state fluorescence and possess optical activity, thereby leading to the fabrication of materials emitting circularly polarized light. Existing organic materials usually suffer from two limitations, a low dissymmetry factor (glum) and weak or no fluorescence in the solid state. Herein, we have demonstrated a naphthalene imide-based dyad system that remains fluorescent even in powder form and displays circularly polarized luminescence in its aggregated and solid state with significantly high glum values. [ABSTRACT FROM AUTHOR]

Semiconductors with visible light catalytic characteristics can realize the degradation of pollutants, CO2 reduction, and hydrogen preparation in sunlight. They have huge application value in the fields of environmental repair and green energy. Graphite phase nitride (g-C3N4, CN) is widely used in various fields such as photocatalytic degradation of pollutants due to its suitable gap width, easy preparation, low cost, fast visible light response, and rich surface activity sites. However, the absorption rate of ordinary CN on visible light is low, and the carriers are easy to recombination, making the lower optical catalytic activity. Therefore, in order to improve the photocatalytic characteristics of the CN, it is necessary to make the surface modification. This article first introduces several main methods for the current surface modification of CN, including size regulation, catalyst embedding, defect introduction, heterostructure construction, etc., and then summarizes the optical catalytic application and related mechanisms of CN. Finally, some challenges and development prospects of CN in preparation and photocatalytic applications are proposed. [ABSTRACT FROM AUTHOR]

(1R,3R,5S,Z)-2-ethylidene-6,6-dimethyl-3-vinylbicyclo[3.1.1]heptane was prepared by hydrovinylation of nopadiene catalyzed by a cationic Ru complex. The structure was fully characterized by 1H- and 13C-NMR spectroscopy, including 2D-COSY and 2D-NOESY spectra, optical rotation, and combustion analysis. In contrast to the previously reported 1,2-hydrovinylation of 1-vinylcycloalkenes by this catalyst, the reaction with nopadiene proceeds by 1,4-addition of ethylene. [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]

The new methacrylic azomethine-containing monomers with side chain quinoline moiety were synthesized by reaction of their corresponding alcohols with methacryloyl chloride. The polymers based on new monomers were synthesized by free radical polymerization. Polymers were characterized by 1HNMR spectroscopy, and the results of their photochemical and optical activities are presented. [ABSTRACT FROM AUTHOR]

The maverick American chemist Russell Earl Marker (1902–1995) is known for his studies on the fragmentation of organic mercury compounds, establishing the concept of the octane number, investigating the rearrangements of hydrocarbons and exploring the relationship between optical rotation and the configuration of organic compounds. His greatest achievement, however, is the elaboration of seminal isolation and synthetic methods of an important class of natural products that helped found a new industry, based on the pharmaceutical chemistry of steroids. The nomadic life of this extraordinary man demonstrates that the enormous obstacles thwarting the progress of science and technology can be surmounted by serendipity, acumen and devotion. However, his premature retirement from chemistry is a warning sign that every scientist is vulnerable and even the toughest man's perseverance can fade if the conditions worsen. [ABSTRACT FROM AUTHOR]

Two new compounds, cladospolides I (1) and J (2), together with two new naturally occurring ones, methyl 11-hydroxy-4-oxododecanoate (3) and 11-hydroxy-4-oxododecanoic acid (4), were isolated from the culture extract of the cold-seep sediment-derived fungus Cladosporium cladosporioides 8-1. Their structures and configurations were established by analysis of 1D/2D NMR, MS, ECD, and specific optical rotation data. Compound 3 was possibly formed by methyl esterification of 4 during the purification process due to the utilization of methanol. All compounds were evaluated for inhibition of four marine phytoplankton species and five marine-derived bacteria. [ABSTRACT FROM AUTHOR]

This work reports on the first computational quantum-chemistry implementation of the hyper-Rayleigh scattering optical activity (HRS-OA), a nonlinear chiroptical phenomenon. First, from the basics of the theory, which is based on quantum electrodynamics, and focusing on the electric dipole, magnetic-dipole, and electric-quadrupole interactions, the equations for the simulation of the differential scattering ratios of HRS-OA are re-derived. Then, for the first time, computations of HRS-OA quantities are presented and analyzed. They have been enacted on a prototypical chiral organic molecule (methyloxirane) at the time-dependent density functional theory level using a broad range of atomic orbital basis sets. In particular, (i) we analyze the basis set convergence, demonstrating that converged results require basis sets with both diffuse and polarization functions, (ii) we discuss the relative amplitudes of the five contributions to the differential scattering ratios, and (iii) we study the effects of origin-dependence and derived the expression of the tensor shifts and we prove the origin-independence of the theory for exact wavefunctions. Our computations show the ability of HRS-OA as a nonlinear chiroptical method, able to distinguish between the enantiomers of the same chiral molecule. [ABSTRACT FROM AUTHOR]

Lithium niobate (LiNbO3) exhibits poor radiation resistance when conventionally implanted with Er at room temperature. To repair the structural disorder, high‐temperature post‐implantation anneals are typically required; however, such treatments can cause sample cracking and dopant redistribution, which are incompatible with device applications. The optimized approach is proposed by performing implants at elevated but acceptably low temperatures to in situ minimize the structural defects generated in the collision cascades, via so‐called “dynamic defect annealing”. Thus, a gradual increase in Er optical activity is shown as a function of irradiation temperature in the range of 25–450 °C, in striking correlation with a decreasing trend for the residual disorder. The impact of moderate post‐implantation anneals is also investigated by comparing the results of anneals of samples implanted at 25 °C and 450 °C. This comparison further confirms the higher optical activation of Er and lower residual structural disorder when the material is initially implanted at elevated temperatures. Based on these data, it is concluded that the use of dynamic defect annealing during the Er implantation of LiNbO3 is a promising strategy for optimizing it as a quantum memory platform, resolving otherwise inevitable trade‐offs. [ABSTRACT FROM AUTHOR]

Proline is a unique amino acid in that its side-chain is cyclised to the backbone, thus giving proline an exceptional rigidity and a considerably restricted conformational space. Polyproline forms two well-characterized helical structures: a left-handed polyproline helix (PPII) and a right-handed polyproline helix (PPI). Usually, sequences made only of prolyl residues are in PPII conformation, but even sequences not rich in proline but which are rich in glycine, lysine, glutamate, or aspartate have also a tendency to form PPII helices. Currently, the only way to study unambiguously PPII structure in solution is to use spectroscopies based on optical activity such as circular dichroism, vibrational circular dichroism and Raman optical activity. The importance of the PPII structure is emphasized by its ubiquitous presence in different organisms from yeast to human beings where proline-rich motifs and their binding domains are believed to be involved in vital biological processes. Some of the domains that are bound by proline-rich motifs include SH3 domains, WW domains, GYF domains and UEV domains, etc. The PPII structure has been demonstrated to be essential to biological activities such as signal transduction, transcription, cell motility, and immune response. [ABSTRACT FROM AUTHOR]

Comprehensive Summary Chiral phosphorescent materials have received extensive research owing to the unique properties of optical activity in recent years. Many phosphorescent carbon dots (CDs) materials have been reported, but the research on chiral phosphorescence is still in the exploratory stage. This work designs multi‐color room temperature phosphorescent (RTP) CDs with chiral signals, which are fully mixed with aromatic aldehyde precursors and chiral amino compounds precursors in a boric acid (BA) matrix and can be easily prepared by solvent‐free thermal method. The prepared (R)‐GCDs, (R)‐YCDs and (R)‐RCDs achieved phosphorescence emission at 545 nm, 582 nm, and 654 nm, respectively, and exhibited corresponding circular dichroism (CD) signals at 341 nm, 394 nm, 384 nm, and 380 nm, 448 nm, and 435 nm, respectively. The longest phosphorescence lifetime is up to 946 ms. Specifically, YCDs exhibit time‐dependent phosphorescence under UV excitation, and the afterglow time under white light excitation can reach 40 s. This article provides a new approach to the study of chiral phosphorescence. [ABSTRACT FROM AUTHOR]

Hybrid metal halides (HMHs) have emerged as a promising platform for optically functional crystalline materials, but it is extremely challenging to thoroughly elucidate the electron transition coupled to additional ligand emission. Herein, to discover sequences of lead‐free HMHs with distinct optically active metal cations are aimed, that is, Sb3+ (5s2) with the lone‐pair electron configuration and In3+ (4d10) with the fully‐filled electron configuration. (Me2NH2)4MCl6·Cl (Me = −CH3, M = Sb, In) exhibits the superior temperature/component‐dependent luminescence behaviors resulting from the competition transition between triplet‐states (Tn‐S0) self‐trapped excitons (STEs) of inorganic units and singlet‐state (S1‐S0) of organic cations, which is manipulated by the optical activity levels of [SbCl6]3− and [InCl6]3−. The bonding differences between Sb3+/In3+ and Cl− in terms of electronic excitation and hybridization are emphasized, and the different electron‐transition mechanisms are established according to the PL spectra at the extreme temperature of 5 to 305 K and theoretical calculations. By fine‐tuning the B‐site Sb3+/In3+ alloying, the photoluminescence quantum yield (PLQY = 81.5%) and stability are optimized at 20% alloying of Sb3+. This research sheds light on the rules governing PL behaviors of HMHs, as well as exploring the optical‐functional application of aviation temperature sensors and access‐control systems. [ABSTRACT FROM AUTHOR]

With the rapid development of high performance computers and computational methods, including software, an increasing number of experimental chemists have tried to use computational methods such as optical rotation (OR, including the matrix model), optical rotatory dispersion (ORD), electronic circular dichroism (ECD or CD), vibrational circular dichroism (VCD), and magnetic shielding constants--nuclear magnetic resonance (NMR)--to explain and/or assign absolute configuration (AC) for various compounds. Such reports in the field of natural products have increased dramatically. However, every method has its range of application. This leads, in some cases, to incorrect conclusions by researchers who are not familiar with these methods. In this review, we provide experimental chemists and researchers with more computational details and suitable suggestions, and especially hope that this experience may help readers avoid computational pitfalls. Finally, we discuss the use of simplified models to replace original complex structures with a long side chain. The fundamental basis for using models to represent complex chiral compounds, such as in OR calculations, is the existence of conformation pairs with near canceling conformer contributions that justify the use of models rather than the original compounds. Using examples, we here introduce the transition state (TS) calculation, which may benefit readers in this area for use and mastery for their AC study. This review will summarize the general concepts involved in the study of AC determinations. [ABSTRACT FROM AUTHOR]

Chiral functionalities exhibited by systems lacking any mirror symmetry encompass natural optical activity, magnetochiral effect, diagonal current-induced magnetization, chirality-selective spin-polarized current of charged electrons or neutral neutrons, self-inductance, and chiral phonons. These phenomena are unified under the hypothesis of "kinetomagnetism of chirality," which posits that any moving (charged or neutral) object in chiral systems induces magnetization in its direction of motion, consequently imparting chirality to the object due to this induced magnetization. We also found conjugate relationships among the kinetomagnetism of chirality, "linear magnetoelectricity," and "electric field-induced directional nonreciprocity," highlighting their interconnections with magnetic, electric, and toroidal orders. The concept of the kinetomagnetism of chirality will be an essential basis for the theoretical understanding of known chiral phenomena, such as natural optical activity or chiral phonons, and also the discovery of unexplored chiral functionalities. [ABSTRACT FROM AUTHOR]

Amyloid fibrils are supramolecular systems showing distinct chirality at different levels of their complex multilayered architectures. Due to the regular long‐range chiral organization, amyloid fibrils exhibit the most intense Vibrational Optical Activity (VOA) signal observed up to now, making VOA techniques: Vibrational Circular Dichroism (VCD) and Raman Optical Activity (ROA) very promising tools to explore their structures, handedness and intricate polymorphism. This concept article reviews up‐to‐date experimental studies on VOA applications to investigate amyloid fibrils highlighting its future potential in analyzing of these unique supramolecular systems, in particular in the context of biomedicine and nanotechnology. [ABSTRACT FROM AUTHOR]

Characterization and understanding of protein higher order structure (HOS) is essential at all stages of biologics development. Here, two folding variants of a bispecific monoclonal antibody, the correctly folded form and an alternative configuration with reduced potency, were characterized by several HOS characterization techniques. Specifically, differential scanning calorimetry (DSC), circular dichroism (CD), Fourier-transform infrared spectroscopy (FTIR), Raman and Raman optical activity (ROA) spectroscopy were used together to elucidate the impacts of disulfide bond scrambling in the fused scFv domains on the structure and thermal stability of the antibody. This study illustrates the importance of selecting appropriate biophysical characterization techniques based on the nature and magnitude of the HOS change. [ABSTRACT FROM AUTHOR]

The Sun's history is still a subject of interest to modern astrophysics. Observationally constrained rates of Coronal Mass Ejections (CMEs) of young solar analogues are still lacking, as those require dedicated monitoring. We present medium-resolution optical spectroscopic monitoring of a small sample of bright and prominent solar analogues over a period of 3 yr using the 0.5-m telescope at observatory Lustbühel Graz (OLG) of the University of Graz, Austria. The aim is the detection of flares and CMEs from those spectra. In more than 1700 h of spectroscopic monitoring, we found signatures of four flares and one filament eruption on EK Dra which has been reported in previous literature, but we complementarily extended the data to cover the latter phase. The other stars did not reveal detectable signatures of activity. For these non-detections, we derive upper limits of occurrence rates of very massive CMEs, which are detectable with our observational setup, ranging from 0.1 to 2.2 d−1, but these may be even smaller than the given rates considering observational biases. Furthermore, we investigate the detectability of flares/CMEs in OLG spectra by utilizing solar 2D Hα spectra from Mees Solar Observatory. We find that solar-sized events are not detectable within our observations. By scaling up the size of the solar event, we show that with a fractional active region area of 18 per cent in residual spectra and 24 per cent in equivalent width time series derived from the same residuals that solar events are detectable if they had hypothetically occurred on HN Peg. [ABSTRACT FROM AUTHOR]

In this work, we present simulations of the optical rotation (OR) for five molecular crystals at density functional theory level with periodic boundary conditions (DFT‐PBC). Calculations are compared with experimental measurements and show semi‐quantitative agreement with experimental data for three of the crystals: tartatic acid, benzil, and pentaerythritol. For the other two crystals, aspartic acid and glutamic acid, the calculated data are in qualitative agreement with, but two orders of magnitude smaller than, the experimental data. We provide some arguments that support the theoretical predictions and suggest that the experiments should be revisited. We also find that the position of H centers provided in experimental X‐ray data is not sufficiently reliable for simulating OR, and better results are obtained when H atoms are allowed to relax while keeping heavier elements fixed at the experimental positions. Comparison with molecular cluster calculations with a better functional and a larger basis set indicate that the role of intermolecular interactions (reproduced with the PBC technique) is as or more important than the choice of model chemistry. Despite the current limitations in the level of theory that can be employed, these simulations provide a promising avenue to investigate the effect of intermolecular interactions on this sensitive electronic property of molecules and materials. [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]

We have carried out a spectral classification by the Activity Types for a subsample of Blazars from the BZCAT v.5 Catalogue, namely the BL Lac (BLL, Lacertids) candidates, designated in the Catalogue as BZB subtype objects. The classification is based on the Sloan Digital Sky Survey (SDSS) homogeneous medium-resolution optical spectroscopy and along with the standard BPT-type diagnostic diagrams, we have applied our newly introduced fine classification scheme with subtypes of Quasars and considering many more features. Out of 1151 BZB objects, 552 having SDSS spectra were classified. After new classification, 259 (46.1%) of 552 have not changed their optical class, and 293 (53.1%) of these objects have changed their optical class. Having this new information on the optical classification we suggest to change the classification of some objects in BZCAT: for 130 BZB objects to BZG, for 18 BZB objects to BZQ and for 145 BZB objects to BZU. [ABSTRACT FROM AUTHOR]

Controlling the optical activity of halide perovskite materials through modulation of the coordination configurations of the metal ions is important. Herein, a novel manganese‐based halide, specifically diaquatetrakis(methyldiphenylphosphine oxide)manganese(II) tetrachloridomanganate(II), [Mn(C13H13OP)4(H2O)2][MnCl4] or [Mn(MDPPO)4(H2O)2][MnCl4] (MDPPO is methyldiphenylphosphine oxide), was synthesized through the solvothermal reaction of MnCl2 with the neutral molecule MDPPO. In this compound, [Mn(MDPPO)4(H2O)2]2+ acts as the cation, while [MnCl4]2− serves as the anion, enabling the co‐existence of tetrahedral and octahedral structures within the same system. Remarkably, the compound exhibits efficient red‐light emission at 662 nm, distinct from the green‐light emission typically observed in MnX4‐based halides. Theoretical calculations show that the red emission comes from the charge transfer from the MDPPO to the Mn2+ of [MnCl4]2−. This work provides a new perspective for the design and synthesis of red‐light‐emitting manganese‐based halides with unique structures. [ABSTRACT FROM AUTHOR]

It is fundamentally challenging to achieve stable and efficient all‐inorganic perovskite solar cells (PSCs) in ambient air conditions for low‐cost commercial manufacturing, as the crystallinity, surface morphology, and optical activity of all‐inorganic perovskites exhibit high sensitivity to environmental factors such as moisture and illumination. Herein, a dual‐doping strategy is presented to prepare high‐quality dual‐doping CsPbI2Br films under ambient air with relative humidity of 70% (70% RH) by introducing CaCl2 and InCl3 additives into precursor solution. The results from the experiments and calculations reveal that the CaCl2 additive can isolate moisture by forming hydrates at the surface and grain boundary of perovskites. Meanwhile, the addition of InCl3 can significantly improve the optoelectronic properties via the heterovalent substitution of Pb2+ by a small amount of In3+. Moreover, the phase segregation can be significantly suppressed in the dual‐doping CsPbI2Br films owing to decreasing the electron–phonon coupling strength and increasing the activation energy of ion migration. The unencapsulated dual‐doping CsPbI2Br PSC with the power conversion efficiency (PCE) of 15.51% (70% RH) demonstrates high humidity storage and long‐term optical stability, remaining 90% of the original PCE after aging 2400 h under ambient air (50% RH) and 1500 h under continuous illumination, respectively. [ABSTRACT FROM AUTHOR]

Hydrogel 3D printing holds immense potential in fields like personalized medicine, regenerative therapies, and organ creation, offering biocompatible structures similar to the extracellular matrix. Gelatin‐Methacryloyl (GelMA) emerges as a promising candidate, while its high viscosity poses a significant challenge, especially in vat photopolymerization‐based 3D printing. Here, a new approach is presented by using Hofmeister ionic effect to substantially reduce the viscosity of high‐content (up to 60%) Gelatin bioink at room temperature with enhanced mechanical performance of the printed structures. The thinning effect induced by chaotropic Hofmeister ions is investigated through complex viscosity analysis, optical rotation measurements, and sol–gel conversion studies. The thinning effect induced by chaotropic ions enables precise 3D printing of Gelatin hydrogel, achieving accuracy comparable to prints made with polymers. Furthermore, after polymerization, the cations of the chaotropic salt change their role to cross‐linkers, leading to stronger scaffolds that exhibit biocompatibility with robust cell attachment, proliferation, and suitability for cell growth. The combination facilitates the creation of customizable structures and high printing accuracy will promote the wide application of Gelatin in the development of patient‐specific implants, drug delivery systems, and tissue scaffolds, further improving medical treatment efficacy and personalized healthcare. [ABSTRACT FROM AUTHOR]

Sensitivity and selectivity of modern electrochemical genotyping methods are insufficient to detect a single-oligonucleotide mismatch in low-concentration native DNA samples. Novel methods of tuning, controlling, and monitoring plasmon modes are necessary to achieve attomolar and higher sensitivity for the modern graphene-based transducers of molecular signals. The electrochemical DNA assay is promising one for applications in the molecular diagnostics of tumors with the genome single-nucleotide polymorphism (SNP) for simultaneously discriminating both wild-type and mutant alleles of the gene in very small concentrations. We offer the plasmon-associated DNA-genotyping method based on the screening effects in assemblies of Raman-optically active conjugates comprising DNA and metallic carbon nanotubes. The impedimetric DNA sensors of non-Faradaic type based on the plasmonic screening effect can be more sensitive than the Raman optical transducer based on Raman DNA optical activity resulting in the plasmon resonance due to liability of the Raman transducer parameters to environmental influence. [ABSTRACT FROM AUTHOR]

Thiophene‐based conjugated polymers show a unique position in the constantly expanding variety of conjugated polymers because of their outstanding optical and conductive characteristics. during the past few decades, many researchers have made significant contributions by developing new methods to create more effective materials for electronic applications. Employing one‐pot Suzuki polycondensation, a unique series of structurally condensed multicolumn/multilayer 3D polymers and oligomers have been developed and synthesized in this research. Polymers were produced with moderate to excellent yields in all instances, as examined by GPC and 1H‐NMR. The results from experiments of optical rotation and AIE investigation, show that the current work will benefit materials research and applications. [ABSTRACT FROM AUTHOR]