High Optical Activity Research Articles

Asymmetric Living Supramolecular Polymerization: Precise Fabrication of One‐Handed Helical Supramolecular Polymers

AbstractProgramming the organization of semiconducting polymers to form well‐defined nanoarchitectures is desirable for fabricating functional materials. In this work, semiconducting copolymers, poly(cholesterol allene)‐b‐poly(3‐hexylthiophene) (PCA‐b‐P3HT) containing helical PCA and poly(alkoxy allene)‐b‐poly(3‐hexylthiophene) (PAA‐b‐P3HT) containing achiral PAA segments, were prepared. Crystallization of P3HT and helicity of PCA drove PCA‐b‐P3HT self‐assemble into spherical nanoparticles that gradually transformed into one‐handed helical nanofibers. The chirality of PCA was transferred to the supramolecular architectures, induced high optical activity in P3HT. Interestingly, the chiral seed micelles of PCA‐b‐P3HT induced asymmetric copolymerization of achiral PAA‐b‐P3HT, which led to helical supramolecular block copolymers with defined helicity and controlled length. Remarkably, the supramolecular copolymers showed white‐light emission and circularly polarized luminescence.

Results of studying the radio and optical variability properties of MRK 501 active galaxy

MRK 501 is a giant radio galaxy with an active core in the constellation Hercules. It is a powerful gamma source. MRK 501 has gamma cyclic variability as well as high X-ray and optical activity. MRK 501 is a quite powerful variable radio source, with a flux density at 15 GHz about 1.2 Jy. Of particular interest is the presence of cyclic brightness variations in gamma and optical ranges, which, according to modern models, may be caused by the presence of a supermassive double black hole in the core of the galaxy MRK 501. In this work, optical observatories of three countries, Ukraine (Mayaki, Heavenly Owl), Slovakia (Vihorlat) and Latvia (Baldone), took part in a joint project to study the rapid variability of AGN in radio and optical bands. The analysis of observations obtained from different observatories in V , R, I bands showed the presence of a wave-like, presumably cyclic, variability in the light curves with an average quasi-period of 46.7 days. Taking into account that a quasi-period of about 23 days was detected in the gamma range, it is most likely that we have found a harmonic (doubled value) of this period in the optical range, which is a new result. In addition, an analysis of long-term variability of MRK 501, from historical light curves of the AAVSO catalog, showed the presence of two longer cycles of variability with quasiperiods of about 1 year and about 5–6 years. It is shown that these quasi-periods, as well as their amplitudes, are unevenly distributed over an observation time interval from 2003 to 2021 (18 years) and change significantly over time.

Secondary ligand engineering of nanoclusters: Effects on molecular structures, supramolecular aggregates, and optical properties

AbstractDeveloping new templates to evaluate the ligand engineering effect in manipulating nanoclusters from both molecular and supramolecular aspects remains highly desired in cluster science because it allows for an in‐depth understanding of structure‐property correlations. We herein presented the secondary ligand (i.e., the phosphine ligand) engineering based on an Ag29 nanocluster template and its dual effects on intracluster structures and intercluster aggregates. The “dissociation‐combination equilibrium” of phosphine ligands on the nanocluster surface was controlled by tailoring the C–H⋯π interactions within the ligand shell, which led to the fabrication of a family of [Ag29(BDT)12(PR3)x]3– nanoclusters. On the molecular level, the dissociation of phosphine ligands contracted the nanocluster framework, while the overall configuration of [Ag29(BDT)12]3– was retained. On the supramolecular level, the complete dissociation of phosphine ligands yielded a bare nanocluster, which followed a chiral crystallization mode, and its crystals displayed high optical activity, derived from circular dichroism and circularly polarized luminescence characterizations. Overall, this work presents the peripheral ligand effects in directionally controlling intracluster configurations and intercluster aggregations, which hopefully benefit future design and preparation of new nanoclusters or cluster‐based nanomaterials with customized structures and performances.

Reaction field induction self-amplification optical activity during polymerization in liquid crystal

A monomer having both chiral induction from nematic liquid crystal (LC) to cholesteric LC and polymerization activity was prepared. Addition of the compound to nematic LC induced the formation of a cholesteric liquid crystal in its chiral form. Subsequent electrochemical polymerization of the monomer produced an optically active polymer with a helical structure as confirmed by circular dichroism (CD) and optical rotatory dispersion measurements. While, the addition of the chiral monomer to an isotropic non-LC solution, and subsequent polymerization resulted a product with no clear optical activity. These results suggest that polymerization of the monomer in a cholesteric environment allows the formation of a polymer with high optical activity. Morphological imprinting from the matrix LC was confirmed by surface observation through polarizing optical microscopy. The chiral monomer changes the surrounding environment to grow into a more highly ordered helical structure. The matrix LC as the environment amplifies the optical activity with helical growth of the monomer during polymerization.

Growth, optical, thermal, electrical, mechanical, and antibacterial activity of hexa aqua nickel bis (P-toluene sulfonate) (HNPS) single crystal

The conventional slow evaporation technique is used in the growth of semi-organic single crystals of Hexa aqua nickel bis (P-toluene sulfonate) (HNPS) and the monoclinic system with centrosymmetric space group (P21/n) is corroborated by single-crystal X-ray diffraction analysis. FTIR vibrational analysis inferred the presence of water molecules CH3 and SO3 groups in grown HNPS crystals. Linear optical parameters explored by UV–Visible spectral analyses ensures the high optical activity of HNPS. The green light emission of HNPS was attributed to Photoluminescence analysis. Thermal analysis encapsulates the thermal stability of HNPS crystals up to 590 °C. The dielectric nature of the material was analyzed for various frequencies at room temperature and an increase in DC conductivity of HNPS suggests the semiconducting behavior of the material while heating. The work hardening coefficient is quantified as 3.7 using mechanical analysis. The thermal and mechanical stability suggests the specific application of HPNS in device fabrications. The synthesized HNPS was tested against two gram-positive bacterial strains (Bacillus subtilis, Staphylococcus aureus) and two gram-negative bacterial strains (Escherichia coli, Pseudomonas aeruginosa) and showed higher significant antibacterial activity against the pathogen.

Perovskite metasurfaces with large superstructural chirality

Recent attempts to synthesize hybrid perovskites with large chirality have been hampered by large size mismatch and weak interaction between their structure and the wavelength of light. Here we adopt a planar nanostructure design to overcome these limitations and realize all-dielectric perovskite metasurfaces with giant superstructural chirality. We identify a direct spectral correspondence between the near- and the far- field chirality, and tune the electric and magnetic multipole moments of the resonant chiral metamolecules to obtain large anisotropy factor of 0.49 and circular dichroism of 6350 mdeg. Simulations show that larger area metasurfaces could yield even higher optical activity, approaching the theoretical limits. Our results clearly demonstrate the advantages of nanostructrure engineering for the implementation of perovskite chiral photonic, optoelectronic, and spintronic devices.

Theoretical analysis of sulfuric acid–dimethylamine–oxalic acid–water clusters and implications for atmospheric cluster formation

In recent years, organic compounds potentially involved in atmospheric particle formation have received increased attention. However, the contributions of organic acids as precursors in nucleation remain ambiguous. In this study, the low-lying structures and thermodynamics of the sulfuric acid–dimethylamine–oxalic acid–water system are obtained at the M06-2X/6-311+G(2d,p) level, and the single point energy of the clusters has been calculated at the DF-LMP2-F12/VDZ-F12 level. The formations of the multicomponent clusters are predicted based on thermodynamics, involving proton transfer and hydrogen bonding interactions. Oxalic acid can synergistically promote the formation of the sulfuric acid–dimethylamine–oxalic acid–water system while inhibiting this with the addition of more sulfuric acid molecules. The results of hydrate distribution show that un-hydrate clusters play a dominant role during formation. Moreover, dimethylamine and oxalic acid have similar effects on Rayleigh scattering properties, and the clusters involving complex mixtures of compounds can have high optical activities.

The structure, electronic and optical properties of 4a,5,8,8a-tetrahydro-5,8-ethano-1,4-naphthoquinone under different pressure

Naphthoquinone organic compounds are widely used in the chemical and pharmaceutical industries. Among them, 1,4-naphthoquinone can be produced stably and used in dyes, anti-tumor drugs, fungicides, etc. Therefore, it is necessary to study its properties under various conditions. In this work, 4a,5,8,8a-tetrahydro-5,8-ethano-1,4-naphthoquinone is analyzed by using density functional theory (DFT) at a pressure of 0–300 GPa to analyze structure, electronic and absorption properties. The changes of crystal bond length and bond angle under different pressure conditions are analyzed in detail. It was found that the main structural changes of the crystal under 90 GPa and 170 GPa pressure. Moreover, the stability of the crystal structure is better in the a- and b-direction than in the c-direction. Then, when analyzing the band gap and density of states (DOS), it can be observed that at 170 GPa, the tetrahydro crystal has undergone a significant change. The absorption spectrum of the crystal also shows the tetrahydro crystal has relatively high optical activity under different pressures, and the corresponding changes with the structural transition are clearly observed at 90, 170, and 200 GPa.

Helical Polycarbenes Bearing D-Prolinol Ester Pendants: An Efficient Catalyst for Asymmetric Michael Addition Reaction

A novel diazoacetate monomer (1) carrying tert-butyloxycarboryl (Boc) protected D-prolinol ester was designed and synthesized successfully. Molecular weight-controlled polymerization of 1 using the complex of π-allylPdCl coordinated Wei-phos (LR) ligand gives a series of helical polycarbenes (poly-1ms) with well-defined molecular weights (Mns) and low polydispersity (Mw/Mns). Removing the protecting Boc groups on the D-prolinol ester pendants leads to the formation of helical poly-1m-As, which showed high optical activity. Furthermore, the poly-1m-As showed high catalytic ability on asymmetric Michael addition reaction (up to 76% ee and 94/6 dr). Both the enantioselectivity and diastereoselectivity of the Michael addition reaction were increased comparing to D-prolinol as catalyst. Moreover, the helical polycarbene catalyst can be easily recovered and reused at least four times without significant loss of its enantioselectivity and diastereoselectivity.

Study of the molecular interaction between hormone and anti-cancer drug using DFT and vibrational spectroscopic methods

The present study is aimed at probing the molecular interaction between Carmustine (anti-cancer drug) and Melatonin (hormone) within the realm of Density functional theory at B3LYP/6–31 G (d,p) level, and using vibrational spectroscopic techniques, namely, FTIR (400–4000 cm–1), Raman (145–3560 cm–1) and surface-enhanced Raman spectroscopy (SERS) (145–3560 cm–1) techniques as well. The vibrational spectra are assigned for both monomers and the interacting complex incorporating the VEDA program and found to be consistent with the experimental findings. NBO analysis has been performed to explore the charge transfer path between Carmustine and Melatonin that provides a reliable insight into the origin of N–H∙∙∙O intermolecular hydrogen bond, which is further supported by the MEP analysis. The complex's thermodynamic and quantum chemical parameters are computed and compared to the respective values of the individual states. The biomolecular complex is found to have low HOMO-LUMO gap and high hyper-polarizability values indicating the complex to be high chemical reactivity and nonlinear optical activity. Moreover, molecular docking analysis is performed to investigate the pharmaceutical activeness of the complex against the selected MIA protein.

Density Functional Theory Study of the High‐Pressure Characterization of Nitrogen‐Rich Energetic Materials: Bis‐Triaminoguanidinium Azotetrazolate (TAGzT)

Using density functional theory calculations, the structural, electronic, and absorption properties of the promising nitrogen‐rich energetic compound bis‐triaminoguanidinium azotetrazolate (TAGzT) under hydrostatic compression of 0–50 GPa are investigated. The results show that TAGzT has a structural transition at the pressure of 29.4 GPa. The results also show that the compressibility of TAGzT is anisotropic, and its structure is much stiffer in the b direction. Analysis of electronic properties shows that TAGzT transforms into a metallic system at 29.4 GPa due to the structural transition, where TAGzT becomes more sensitive under the pressure compression. The absorption spectra indicate that TAGzT has higher transparency in the infrared region and high optical activity in UV light, and its optical activity increases as pressure increases. This study may provide useful information for understanding how TAGzT behaves under high pressure.

Progress in the chemistry of functional aramids properties

AbstractHigh‐performance polymers based on amide aromatic rings are known as wholly aromatic polyamides or aramids. The arrangement and admirable properties of aramids are built on the basis of amide linkage and rigid aromaticity. Aramids are attractive because of their extraordinary bond strengths and very high stiffness. Synthetic aromatic polymeric chains provide increased mechanical resistance and thermal softening compared to aliphatic aramids. In addition, aramids exhibit high thermal stability, low creep, and good optical activity with fluorescence. Hence, aramids are found in advanced arenas for engineering thermoplastics such as transport applications, electroactive materials, films, bullet‐proof body armor, smart materials, protective clothing, fibers, in nanocomposites as asbestos alternatives, cutting edge complexes in arming, high‐temperature lining material, in space engineering, and more. The objective of this review is to make the field of aramids functionality more accessible to the materials science community, that is, scientists, academicians, and engineers.

Smartphone-based fluorometer for pH detection using green synthesized carbon dots

As a group of heavy-metal-free fluorescent nanomaterials, carbon dots (CDs) have recently received a growing interest as they have high optical absorption activity and are chemically stable, biocompatible, and less toxic. In this paper, the green synthesis of stable CDs by hydrothermal and pyrolysis methods from Parmigiano-Reggiano is performed. An intrinsically emitted fluorescence results from simultaneous generation and the surface passivation of CDs by the mentioned techniques. The responses of hydrothermal CDs to pH occur by emission wavelength at 430 nm under 365 nm excitation. When the pH is increased from 2–12, its emission fluorescence intensity will be reduced. The pH was also analyzed real time by developing a smartphone-based portable recognition platform consisting of an instrument and a self-designed APP called “Image Analyser”. The fluorescence color change of CDs caused by the pH was recorded by the camera of the smartphone and color of pictures was analyzed by APP. The results of both methods are similar, so the CDs based recognition platform are highly practically and efficient tool as they could analyze pH with outstanding functionality, as examined in this study in different samples.

Self-Assembly of Earth-Abundant Supraparticles with Chiral Interstices for Enantioselective Photocatalysis

Chiral nanostructures have been extensively studied for bioanalysis and optoelectronics because of their high rotatory optical activity but not for enantioselective catalysis because of the chirali...

Highly Regioselective and Helix-Sense Selective Living Polymerization of Phenyl and Alkoxyallene Using Chiral Nickel(II) Catalysts

Facile synthesis of high optically active helical polymers from achiral monomers still remains a great challenge. In this work, two chiral Ni(II) catalysts bearing chiral R- or S-2a ligands were facilely prepared which can efficiently initiate the living/controlled polymerization of allene monomers and afford well-defined polyallenes in high yields with controlled molecular masses (Mₙs) and low molecular mass distributions (Mw/Mₙs). The catalysts showed interesting regioselectivity on the cumulated double bonds of allene monomers, as the polymerizations were highly selective which occurred on 2,3-double bonds. Moreover, the polymerization of achiral allene monomers using chiral Ni(II) catalysts showed remarkable helix-sense selectivity. The yielded polyallenes exhibited high optical activity due to the formation of a predominant one-handed helix as revealed by circular dichroism, UV–vis, and direct atomic force microscopy (AFM) observations as well. The predominant one-handed helicity of the generated polyallenes was solely determined by the chirality of the Ni(II) catalysts.

An Efficiently Reworkable Thermosetting Adhesive Based on Photoreversible [4+4] Cycloaddition Reaction of Epoxy‐Based Prepolymer with Four Anthracene End Groups

AbstractThe solid–liquid phase transition is always the key to the design and preparation of reworkable adhesives. However, an efficient photoinduced reworkable thermosetting adhesive at room temperature remains a challenge. Here, a photoinduced reworkable thermosetting adhesive of epoxy‐based prepolymer with four anthracene end groups are prepared. The highly active light‐induced [4+4] cycloaddition and depolymerization, as well as a large number anthracene groups endow this adhesive with high optical activity. Soft segments of polyether amines are used to adjust glass transition temperature of these cross‐linked networks which is significant for highly efficient solid–liquid phase transition of photoinduced reworkable adhesive at room temperature. As a reworkable adhesive, the obtained AER/D2000 exhibits desirable viscosity, lap shear strength up to 2.4 MPa for quartz glass substrate in the cross‐linked state, and ideal reworkable efficiency as high as 91.7%. Therefore, this research provides a strategy for a photoinduced reworkable adhesive, and as an alternative for heat‐induced reworkable adhesives.

Salinity enhances high optically active L-lactate production from co-fermentation of food waste and waste activated sludge: Unveiling the response of microbial community shift and functional profiling

Lactic acid (LA), a versatile platform molecule, can be fermented from organic wastes, such as food waste and waste activated sludge. In this study, an efficient approach using salt, a component of food waste as an additive, was proposed to increase LA production. The LA productivity was increased at 10 g NaCl/L and optical pure L-lactate was obtained at 30 g NaCl/L. The enhancement of LA was in accordance with the increased solubilization and the critical hydrolase activities under saline conditions. Moreover, high salinity (30–50 g NaCl/L) changed the common conversion of LA to volatile fatty acids. In addition, the key LA bacteria genera (Bacillus, Enterococcus, Lactobacillus) were selectively enriched under saline conditions. Strong correlations between salinity and functional genes for L-LA production were also observed. This study provides a practical way for the enrichment of L-LA with high optical activity from organic wastes.

Record-high positive refractive index change in bismuth germanate crystals through ultrafast laser enhanced polarizability

Unlike other crystals, the counter intuitive response of bismuth germanate crystals ({text {Bi}}_4{text {Ge}}_3{text {O}}_{12}, BGO) to form localized high refractive index contrast waveguides upon ultrafast laser irradiation is explained for the first time. While the waveguide formation is a result of a stoichiometric reorganization of germanium and oxygen, the origin of positive index stems from the formation of highly polarisable non-bridging oxygen complexes. Micro-reflectivity measurements revealed a record-high positive refractive index contrast of 4.25times 10^{-2}. The currently accepted view that index changes >1times 10^{-2} could be brought about only by engaging heavy metal elements is strongly challenged by this report. The combination of a nearly perfect step-index profile, record-high refractive index contrast, easily tunable waveguide dimensions, and the intrinsic high optical non-linearity, electro-optic activity and optical transparency up to 5.5,upmu {text {m}} of BGO make these waveguides a highly attractive platform for compact 3D integrated optics.

Recyclable Helical Poly(phenyl isocyanide)-Supported l-Proline Catalyst for Direct Asymmetric Aldol Reaction in Brine

A novel helical poly(phenyl isocyanide) bearing Boc protected l-proline pendants (poly-1m) was designed and synthesized. Removed the protecting Boc groups on the l-proline pendants led to the formation of helical polymer poly-2m, which showed high optical activity owing to the preferred right-handed helix of polyisocyanide main chain. Optically active helical poly-2m showed excellent catalytic ability on asymmetric aldol reaction. Helical polymer catalysts exhibited enhanced stereoselectivity in aldol reaction compared to small molecule l-proline. Under the optimized aldol reaction condition, the enantiomeric excess (ee) and diastereomeric ratio (dr) values of the aldol reaction product were respectively up to 90% and > 20/1. Moreover, the helical polyisocyanide catalyst Poly-2m can be easily recovered and reused in the aldol reaction for at least five cycles with maintained its activity and stereoselectivity. Enantioselective aldol reaction catalyzed by poly-2m.

Three‐dimensional Random Dielectric Colloid Metamaterial with Giant Isotropic Optical Activity

AbstractMotivated by the theoretical observation that isotropic chirality can exist even in completely random systems, a dielectric metamaterial consisting of a random colloid of meta‐atoms is designed, which exhibits unprecedentedly high isotropic optical activity. Each meta‐atom is composed of a helically arranged cluster of silicon nanospheres. Such clusters can be fabricated by large‐scale DNA self‐assembly techniques. It is demonstrated that the use of a high concentration of the meta‐atoms in the colloid provides significant suppressions of incoherent scattering losses. As a result, the proposed system shows three orders of magnitude improvement of isotropic optical activity as compared with the previous metamaterial designs. This work highlights the significant potential of completely random systems, which are commonly produced in colloidal sciences, for applications as metamaterials toward novel photonic effects and devices.