A planar chiral nanostructure with asymmetric transmission of linearly polarized wave and huge optical activity in near-infrared band

Just like an electronic diode that allows the electrical current to flow in one direction only, a kind of chiral metamaterial structure with a similar functionality for the electromagnetic wave is proposed. The designed nanostructure that consists of twisted metallic split-ring resonators on both sides of a dielectric substrate achieves asymmetric transmission for a forward and backward propagating linearly polarized wave by numerical simulation in near-infrared band. Difference in transmission efficiency of the optimized structure between the same polarized waves incident from opposite directions can reach a maximum at the communication wavelength （1.55 μm）. Moreover, the simulation results of this structure also exhibit strong optical activity and circular dichroism.

Synthesis, Characterization and Conductivity of α-Keggin-type Nanoparticles, Co(en)_3PMo_(12)O_(40)·8H_2O with Optical Activity

Polyoxometallates Co(en) 3PMo 12O 40·8H 2O(+,-)[abbreviated as PMo 12-Co(+,-)], nanoparticles were synthesized by the chemical precipitation reaction at room temperature for the first time. They were characterized by means of elemental analyses, IR spectrometry and X-ray diffraction. The images of scanning electron microscopy(SEM) and the results of calculation by using the Scherrer equation for the line widths of the XRD patterns were used to estimate the average particle size of the powder products, which was 40 nm. The results show that the nanoparticle size was affected by starting materials′ concentrations. The particles had a small size and a narrow distribution, when the concentrations of H 3PMo 12O 40·24H 2O and Co(en) 3I 3·H 2O were around 1.7×10 -4 and 1.0×10 -3 mol/L, respectively. When the concentration was increased, there was no significant increase in the particle size, but more polydisperse Co(en) 3(PMo 12O 40) (+, -) were obtained. In poly(ethylene glycol)(PEG) with an average molecular weight(M W) of 600 g/mol and containing LiClO 4[n(O)/n(Li)=100∶1] as the supporting electrolyte, the conductivity of the composite system increases upon the addition of PMo 12-Co(+ or -) nanoparticles, which was measured by the a.c. impedance technique. The interactions among PEG, LiClO 4, PMo 12, and Co can be used to explain that the PMo 12-Co(+ or -) nanoparticles could promote the conductivity of the PEG-LiClO4-PMo12-Co system.

Studies on the Relationship between the Helical Structure and Optical Activity of Some Chiral Cyclic Esters Ⅱ

A method for the analysis of the relationship between the helical structure and optical activity was proposed by the study of the conformations and X-ray diffraction structures of some cyclic esters prepared by esterification of L-(-)-2.3-O-methylidene threitol and L-(+)-2,3-O-isopropplidene threitol with alkanedioyl dichlorides and o-,m-,and p-phthaloyl dichlorides.

Helioal Structure and Optical Activity of Two New Derivatives of R(+)-1,1'-Binaphthyl-2,2'-diol

Correlation between the belieal structure and optical activity of two derivatives of R(+)- 1, 1'-binaphthyl-2,2'-diol was derived from a study of their optical rotations, CD curves and Xray crystal structures.

Remotely excited Raman optical activity using chiral plasmon propagation in Ag nanowires

We experimentally investigated remotely excited Raman optical activity(ROA)using propagating surface plasmons in chiral Ag nanowires.Using chiral fmoc-glycyl-glycine-OH(FGGO)molecules,we first studied the local surface plasmon-enhanced ROA.We found that the Raman intensity can be excited by left-and right-circularly polarized lights and that the circular intensity difference(CID)can be significantly enhanced.Second,by selecting vibrational modes with large Raman and ROA intensities that are not influenced by chemical enhancements,we studied remotely excited ROA imaging and the CID of FGGO molecules by propagating a plasmonic waveguide using Ag chiral nanostructures.When laser light was radiated on one of the Ag terminals,the measured CID of the FGG at the other terminal showed little change compared to the local excited CID.Meanwhile,when the laser light was radiated on the Ag nanowires(not on the terminals)and was coupled to the nearby nanoantenna,the CID of the ROA could be manipulated by altering the coupling angle between the Ag nanowires.To directly demonstrate the propagation of ROA along the nanowire and its remote detection,we also measured the remotely excited ROA spectra.Our experimental method has the potential to remotely determine the chirality of molecular structures and the absolute configuration or conformation of a chiral live cell.

Controllable optical activity with non-chiral plasmonic metasurfaces

Optical activity is the rotation of the plane of linearly polarized light along the propagation direction as the light travels through optically active materials.In existing methods,the strength of the optical activity is determined by the chirality of the materials,which is difficult to control quantitatively.Here we numerically and experimentally investigated an alternative approach to realize and control the optical activity with non-chiral plasmonic metasurfaces.Through judicious design of the structural units of the metasurfaces,the right and left circular polarization components of the linearly polarized light have different phase retardations after transmitting through the metasurfaces,leading to large optical activity.Moreover,the strength of the optical activity can be easily and accurately tuned by directly adjusting the phase difference.The proposed approach based on non-chiral plasmonic metasurfaces exhibits large optical activity with a high controllable degree of freedom,which may provide more possibilities for applications in photonics.

Self-accelerated optical activity in free space induced by the Gouy phase

Optical activity(OA)is the rotation of the polarization orientation of the linearly polarized light as it travels through certain materials that are of mirror asymmetry,including gases or solutions of chiral molecules such as sugars and proteins,as well as metamaterials.The necessary condition for achieving OA is the birefringence of two circular polarizations in material.Here,we propose a new kind of self-accelerated OA in free space,based on the intrinsic Gouy phase induced mode birefringence of two kinds of quasi-non-diffracting beams.We provide a detailed insight into this kind of self-accelerated OA by analyzing angular parameters,including angular direction,velocity,acceleration,and even the polarization transformation trajectory.As the Gouy phase exists for any wave,this kind of self-accelerated OA can be implemented in other waves beyond optics,from acoustic and elastic waves to matter waves.

Fine-tune chiroptical activity in discrete chiral Au nanorods

Accurate researches on the surface plasmon resonance(SPR)-based applications of chiral plasmonic metal nanoparticles(NPs)still remain a great challenge.Herein,a series of chiral plasmonic metal NPs,e.g.,chiral Au nanorods(c-Au NRs),c-Au@Ag core–shell,and c-Au@TiO_(2) core–shell NRs,with different chiroptical activities have been produced.Plasmonic circular dichroism(PCD)bands of c-Au NRs can be precisely tailored by tuning the longitudinal SPR(LSPR)and amount of Au NRs as seeds.Besides,a shift of PCD bands within ultraviolet–visible–near infrared ray(UV–vis–NIR)region can also be achieved through the functionalization of a shell of another metal or semiconductor.Interestingly,chirality transfer from c-Au core to Ag shell leads to new PCD bands at the near-UV region.The tuning of PCD bands and chirality transfer are confirmed by our developed theoretical model.Developing chiral Au NRs-based chiral plasmonic nanomaterials with tunable chiroptical activities will be helpful to understand the structure-direct PCD and to extend circularly polarized-based applications.

Giant intrinsic chiro-optical activity in planar dielectric nanostructures

The strong optical chirality arising from certain synthetic metamaterials has important and widespread applications in polarization optics,stereochemistry and spintronics.However,these intrinsically chiral metamaterials are restricted to a complicated three-dimensional(3D)geometry,which leads to significant fabrication challenges,particularly at visible wavelengths.Their planar two-dimensional(2D)counterparts are limited by symmetry considerations to operation at oblique angles(extrinsic chirality)and possess significantly weaker chiro-optical responses close to normal incidence.Here,we address the challenge of realizing strong intrinsic chirality from thin,planar dielectric nanostructures.Most notably,we experimentally achieve near-unity circular dichroism with~90%of the light with the chosen helicity being transmitted at a wavelength of 540 nm.This is the highest value demonstrated to date for any geometry in the visible spectrum.We interpret this result within the charge-current multipole expansion framework and show that the excitation of higher-order multipoles is responsible for the giant circular dichroism.These experimental results enable the realization of high-performance miniaturized chiro-optical components in a scalable manner at optical frequencies.

Polymerizable AEE-active Dye with Optical Activity for Fluorescent Nanoparticles Based on Phenothiazine:Synthesis,Self-assembly and Biological Imaging

In consideration of various advantages such as less harm,higher sensitivity,and deeper imaging depth,etc.,AIE materials with longwave emission are attracting extensive attention in the fields of vascular visualization,organelle imaging,cells tracker,forensic detection,bioprobe and chemosensor,etc.In this work,a novel fluorescent(R)-PVHMA monomer with chirality and aggregation-induced emission enhancement(AEE)characteristics was acquired through enzymatic transesterification reaction basing on phenothiazine,and its[α]D25℃value was about-6.39°with a 3.08 eV bandgap calculated by the quantum calculations.Afterwards,a series of PEG-PVH1 and PEG-PVH2 copolymers with chirality feature were achieved through RAFT polymerization of the obtained(R)-PVHMA and PEGMA with various feed ratios.When the feed molar ratio of(R)-PVHMA increased from 21.5%to 29.6%,its actual molar fractions in the PEG-PVH1 and PEG-PVH2 copolymers accordingly increased from 18.1%to 25.7%.The molecular weight of PEG-PVH1 was about 2.2×10^(4) with a narrow PDI,and their kinetics estimation showed a first-order quasilinear procedure.In aqueous solution,the amphiphilic copolymers PEG-PVH could self-assemble into about 100 nm nanoparticles.In a 90%water solution of H_(2)O and THF mixture,the fluorescence intensity had the maximum value,and the emission wavelength presented at 580 and 630 nm.The investigation of cytotoxicity and cells uptake showed that PEG-PVH FONs performed outstanding biocompatibility and excellent cells absorption effects,which have great potential in bioimaging application.

Chiral nanoparticle-induced amplification in optical activity of molecules with chiral centers

Sensitive differentiation of an enantiomer from its mirror image(ie,enantiodifferentiation),a perennial challenge for pharmaceutical production and disease diagnosis,is technically limited by the weak optical activity(OA)of enantiomers,mainly due to their dimensional mismatch with light wavelengths in the ultraviolet(UV)-visible region.Here we use silver chiral nanoparticles(Ag CNPs)with nominally sub-5 nm helical pitch(P)to amplify the OA of(20R,30R,40S)-riboflavin-50-phosphate sodium salts(RP),which have been found to indirectly affect metabolic processes,through the formation of an RP thin film(TF)covering a close-packed array of Ag CNPs.The OA of the RP in the deep-UV region can be amplified up to 80-fold,ascribed to the aggregation of RP in the TFs and the interactions between RP and the atomically chiral lattices at the CNPs'surfaces.The former contribution,not associated with the chiral Ag topographies,plays a dominant role by thickening the RP TFs,so that the observed amplification has no enantioselective dependence on the chirality of the Ag CNPs.This study extends progress in the sensitive detection of bio-enantiomers,which is highly desired for advanced bio-detection in disease diagnosis and production of single-enantiomer pharmaceuticals.

Inorganic Nanostructures with Strong Chiroptical Activity

Chirality is one of the most remarkable geometrical properties with a variety of manifestations in the material world.The discovery of chirality in inorganic nanostructures spurred the rapid growth of fundamental and applied studies involving chiral nanoscale particles in chemistry,biology,medicine,and physics.While many factors make chiral inorganic nanostructures significant to researchers from many backgrounds,the unique characteristic that drives research in this area is their ability to exhibit high chiroptical activity.In this review,we specifically address its origin in juxtaposition with chiral organic nanostructures.Chiroptical activity depends on multiple factors,including the degree of asymmetry and the size of the object,compared with light wavelength.Nonetheless,it is the high polarizability that distinguishes chiral inorganic matter from what is known from organic chemistry and biology.More importantly,strong light-matter interaction between chiral nanostructures and circularly polarized photons has direct implications for the long-standing fundamental questions about the origin of homochirality on earth and new possibilities for chiral catalysis.Increased insight into chiroptical activity also deepens the existing knowledge about the nanoscale matter and expands its technological applications.

NEW OPTICALLY ACTIVE AROMATIC POLYIMIDES Ⅱ: SYNTHESIS AND PROPERTIES OF OPTICALLY ACTIVE AROMATIC POLYIMIDE BASED ON (R)-(+)-2, 2′-BIS (2-TRIFLUORO-4-AMINOPHENOXY)-1, 1′-BINAPHTHYL

Optically active (R)-(+)-2, 2' -bis(2 -trifluoro-4 -aminophenoxy)- 1, 1' -binaphthyl was prepared from1, 1'-bi-2-naphthol. The optically active aromatic polyimide was also successfully synthesized. This newpolymer has good solubility, thermal stability etc. Its specific rotation was found to be +174°, and itschiroptical property was also studied.

SYNTHESIS OF OPTICALLY ACTIVE POLY (N-VINYLCARBAZOLE)S

The organic salts as initiators [A*B-+(-):Ph*3C+ClO4-, Ph(3)*C+SbCl6-, (-)Sp*(ClO4-)-Cl-+ and (-)(Sp)(2)*(+3)(ClO4-)(3)] and catalysts [A(+)B*(-):(+)CSA*, A*B-+*(-):Ph(3)*C+(+)CSA*(-) and (-)Sp*(+)(+)CSA*] are prepared and characterized by specific rotation. The asymmetrically stereoselective induction of the initiators and catalysts in thc polymerization of N-vinylcarbazole is in an order of A*B-+*(-) > A(+)B*(-) > A*B-+(-). The specific rotations of obtained poly(N-vinylcarbazole) (PVCZ) generally are in accordance with mentioned order.

STUDY ON METHANOLYSIS STABILITY OF OPTICALLY ACTIVE COPOLYMERS OF TRIPHENYLMETHYL METHACRYLATE AND METHYL METHACRYLATE

The methanolysis of poly(triphenylmethyl methacrylate) (PTrMA) and its copolymers P(TrMA-co-MMA), P(TrMA-b-MMA) has been studied in the presence of anhydrous methanol at 40 degrees C by electroconductometric method. It has been found that the methanolysis stability can be obviously improved for the copolymer, especially, the radom copolymer, P(TrMA-co-MMA).

Study on Optical Activities of A3BGa3Si2O14 Crystals

Four crystals with the general formula of A3BGa3Si2O14 （A = Ca^2＋, Sr^2＋; B=Nb^5＋ , Ta^5＋） grown by using the Czoehralsky technique were reported. They are all uniaxial and belong to 32 point group. Their transmission, rotatory angle and specific rotation dispersion were investigated by speetrophotometer and compared with LGS. The transmission spectra show that they are transparent in the visible wavelength region beyond 294 nm and infrared region, and their transmission are all larger than that of LGS.The transmission spectra between parallel polasizers show that they have large optical activities which are larger than that of LGS. Of the four crystals, Sr3NbGa3Si2O14 has the largest optical activity ： 240.75 （°）·mm^-1 at 0.30 μm wavelength, 34.73 （°） ·mm^-1 at 0. 633 μm wavelength. The Bohzmann＇s coefficients of these crystals were calculated, which were in good agreement with earlier measurement in other reference.

OPTICALLY ACTIVE COPOLYESTERS BASED ON AXIALLY DISSYMMETRIC 1,1’-BINAPHTHALENE-2,2’-DIYL UNITS

Optically active copolyesters based on axially dissymmetric 1,1'-binaphthalene-2,2'-diyl units have been preparedand characterized by specific rotation, ^(13)C-NMR and CD spectra. The results show that the rotation signs of tribasiccopolyesters or the mixture of corresponding homopolyesters obey a three dimensional quadrant pattern. The composition ofthe copolyesters was determined from ^(13)C-NMR spectra to be triad sequence distributions and corresponding with the ratioby feed.

The Parameters Selection of SMA Optically Activated and Its Application

Shape Memory Alloy (SMA) optically activated is the key technology of optical SMA activator.According to the shape memory mechanism of SMA,researches are done on the activating response time and light wavelength of activating source etc of SMA optically activated to approach the parameters selection of optical activation.SMA has the optimum efficiency in the range of 13 seconds to 27 seconds when SMA is illuminated continuously by wavelength of 675nm;The power of light wave has a low effect on SMA;The longer the activating wavelength,the quicker the response time of SMA activated.If the proper activating time and activating wavelength are adopted, and the structure deformation of composite material of SMA imbedded may be actively controlled,an ideal effect will be gotten.The research provides an evidence for the design of optical SMA activator and is of great significance to its application.The research on smart structure has a wide application prospect.

Baker's Yeast Mediated Reduction of Optically Active Diketone

Baker's Yeast mediated reduction of optically active diketone has been described.

Dual-Wavelength Bad Cavity Laser as Potential Active Optical Frequency Standard

We experimentally realize the dual-wavelength bad cavity laser for the first time. As the Cs cell temperature is kept between 118℃ and 144℃, both the 1359nm and 147Ohm lasing outputs of dual-wavelength bad cavity laser are detected. The laser output power of dual-wavelength bad cavity laser is measured when changing the 455 nm pumping laser frequency and power at 127℃ Cs cell temperature. Both the 1359 nm laser and the 1470 nm laser are working at the deep bad cavity regime, and the ratio between the linewidth of cavity mode and the laser gain bandwidth a ≈ 40 for 1359nm and 1470nm lasers. The 147Ohm laser linewidth is measured to be 407.3Hz. The dual-wavelength bad cavity laser operating on atomic transitions demonstrated here has a potential in the application as a stable optical local oscillator, even an active optical frequency standard directly in the future.