Circularly polarized luminescence induced by excimer based on pyrene-modified binaphthol

A new chiral bromobinaphthol-pyrene compound was developed to achieve a green circularly polarized luminescence (CPL) from its excimer with a dissymmetry factor (|g_lum|) value of 4.3×10^-3 and a high quantum yield Φ_{F, solid} up to 55.9%, while no CPL signals could be observed for the blue luminescence from unimolecule. Meanwhile, reversal CPL signals can be observed from both concentrated solution and solid.     

Chirality induction of polyaniline derivatives through chiral complexation

Chirality induction of π-conjugated polyaniline derivatives was achieved by chiral complexation with chiral palladium(II) complexes. The crystal structure of the chiral conjugated complex with a model compound of the polyaniline, N,N-bis(4^′-dimethylaminophenyl)-1,4-benzoquinonediimine, revealed a chiral propeller twist conformation of the π-conjugated moiety.     

Optical manipulation with nanoscale chiral fields and related photochemical phenomena

Chiral light-matter interaction occurs when the system consists of the matter and the light has a chiral structure, which is generically called the chiro-optical effect. Circular dichroism and optical rotation are representative spectroscopic methods based on chiro-optical effects. Chiro-optical effects have been widely utilized to detect chiral materials in the system. The chiro-optical effect also has the potential to create chiral materials from achiral materials and chiral optical fields, and to generate chiral optical fields from chiral matter systems. To achieve that, the design and observation of chiral optical field structures are essential. In this article, we describe local chiral optical fields generated in the peripheries of nanomaterials (typically metal nanostructures) irradiated with light. We summarize basic characteristics of nanoscale local chiral optical fields, methods to observe/control the chiral optical field structures at nanomaterials. Then some chemical, optical, and mechanical effects of designed chiral optical fields are described. Chiral nanostructures were created from achiral nanomaterials combined with circularly polarized light. Nucleation of chiral crystals of achiral molecules was achieved by circularly polarized light with the aid of plasmonic materials. Circularly polarized luminescence was observed from achiral fluorescent molecules conjugated with chiral plasmonic nanostructures. On mechanical characteristics, optical forces exerted on chiral materials were found to be dependent on the handedness of incident circularly polarized light, which can be utilized to discriminate the chirality of the material. The concept can be further generalized to the spin-dependent asymmetric light-matter interactions, which will create not only the molecular- and nano-scale chiral structures but also various novel functions of materials that are correlated with the handedness degree of freedom.     

Chirality induction of π-conjugated chains through chiral complexation

Chirality induction of π-conjugated polyanilines through chiral complexation with the chiral palladium(II) complexes was demonstrated to afford the chiral conjugated polymer complexes. Complexation of the emeraldine base of poly(o-toluidine) (POT) with the chiral palladium(II) complex bearing one labile coordination site led to the formation of the chiral conjugated polymer complex, which exhibited an induced circular dichroism (ICD) based on the chirality induction into a π-conjugated backbone. The mirror image of the CD signal was observed with the chiral conjugated polymer complex, which was obtained from the chiral palladium(II) complex possessing the opposite configuration. The chirality of the podand ligand moieties of the palladium complex is considered to induce a propeller twist of the π-conjugated molecular backbone. The crystal structure of the chiral conjugated complex of N-bis(4′-dimethylaminophenyl)-1,4-benzoquinonediimine (L³) as a model compound of the polyaniline revealed a chiral propeller twist conformation of the π-conjugated backbone. Furthermore, chiral complexation with the cationic palladium(II) complexes provided the ionic chiral conjugated complexes.     

点手性调控的三股铕螺旋体的非对映选择性自组装及圆偏振发光

具有超分子手性的稀土螺旋体为合成高性能稀土圆偏振发光(CPL)材料提供了结构基础.然而,稀土Ln(Ⅲ)离子较大的半径和不稳定的配位几何构型为合成高光学纯度的稀土螺旋体带来了困难和挑战.本工作通过在双三齿配体端基引入点手性的方式成功构筑了一对儿对映体纯的手性双核三股铕螺旋体,[Eu2(LRR)3](OTf)6和[Eu2(...     

Construction of Supramolecular Chirality in Polymer Systems:Chiral Induction,Transfer and Application

Chirality, commonly found in organisms, biomolecules and nature such as L-amino acids and D-sugars, has been extensively studied in chemistry and biomedical science. Hence, the demand for simple and efficient construction of chiral structures, especially chiral polymers, has been rapidly growing due to their potential applications in chemosensors, asymmetric catalysis and biological materials. However, most chiral polymers reported are prepared directly from chiral monomers/chiral catalysts, the...     

Advances in circularly polarized luminescent materials based on axially chiral compounds

Circularly polarized (CP) light, as a special form of polarized light, demonstrates potential application prospects in future displays and optoelectronic technologies. Circularly polarized luminescence (CPL) from chiral chromophores is an ideal method to directly generate CP light, but how to design efficient emitters is always a perplexing problem. Among various chiral materials, CPL materials with axial chirality can provide us with clear structural parameters and information to further explore the structure-activity relationship. Herein, we systematically summarize the development status of axially chiral compounds with CPL properties from two aspects of photoluminescence and electroluminescence, covering metal complexes, polymers, supramolecular assemblies, simple organic molecules, and liquid crystals systems. In addition, we initially explore the relationship between CPL performance and axially chiral configuration, and the current challenges and opportunities in this vibrant field are also discussed.     

Tuning the (Chir)Optical Properties and Squeezing out the Inherent Chirality in Polyphenylene-Locked Helical Carbon Nanorings

Distorting linear polyaromatic hydrocarbons (PAHs) out of planarity affects their physical properties and breaks their symmetry to induce inherent chirality. However, the chirality cannot be achieved in large distorted PAHs-based macrocycles due to a low racemization barrier for isomerization. Herein, we report the precise synthesis and tuning size-dependent (chir)optical properties of a new class of chiral PAHs-containing conjugated macrocycles (cyclo[n]paraphenylene-2,6-anthrylene, [n]CPPAn_2,6 ; n=6–8). Their inherent chiralities were squeezed out in small anthrylene-based macrocycles. Efficient resolutions for chiral enantiomers with (P)/(M)-helicity of small [6-7]CPPAn s were achieved by HPLC. Interestingly, these macrocycles showed enriched size-dependent physical, chiral, and (chir)optical properties. Theoretical calculations indicate that these macrocycles have high strain energy (E_strain=60.8 to 73.4 kcal/mol) and very small E_gap (∼3.0 eV). Notably, these enantiomers showed strong chiroptical properties and dissymmetry factors (|g_abs| and |g_lum|∼0.01 for an enantiomer of [6]CPPAn_2,6 ), which can give them potential applications in optically active materials.     

Multilevel Chirality Transfer from Amino Acid Derivatives to Circularly Polarized Luminescence-Active Nanoparticles in Aqueous Medium

Chirality at different levels is widely observed in nature, but the clue to connect it all together, and the way chirality transfers among different levels are still obscure. Herein, a l -/d -lysine-based self-assembly system was constructed, in which two-step chirality transfer among three different levels was observed in aqueous solution. The chirality originated from the point chirality of amino acid derivatives l -/d -PyLys hydrochloride, and was transferred to the planar conformational chirality of water-soluble pillar[5]arene pR-/pS-WP5. Then, with the aid of pR-/pS-WP5, nanoparticles were formed that exhibited L-/R-handed circularly polarized luminescence with a dissymmetry factor of up to ±0.001, arising from pyrene chiral excimers. This multilevel chirality transfer not only provides a perspective to trace potential clues, and to pursue certain ways by which the chirality transfers, but also offers a strategy to create controllable CPL emission in aqueous media.     

Binary 1,4-asymmetric induction toward imines from a single allyltin reagent with a chiral oxygen functional group

A single allyltin reagent possessing a chiral oxygen functional group afforded each diastereomeric product in the reaction with N-sulfonylimines promoted by appropriate Lewis acids in a binary stereoselective manner. InCl₃ selectively provided the syn-1,4-amino alcohol derivatives, while BF₃ and TiCl₄ gave the anti-products preferentially.     

Optical Chirality Induced in Evaporated Poly(diacetylene) Film by Circularly Polarized Light

Summary: 10,12-tricosadiynoic acid films were deposited on glass substrate by vacuum evaporation proceess at substrate temperatures of 273 K and 313 K, and then photopolymerized using left- and right- circularly polarized light (CPL). The resulting prepared poly(diacetylene) films changed from blue phase to red phase successfully by sample annealing at 353 K for 10 min, and the absorption spectra well reflected the red phase. Surface morphology change was not observed by anneling at 353 K. Furthermore, the CD spectra revealed that the chirality induced by CPL at 313 K was stronger that at 273 K.     

Chirality induction in cyclopolymerization. VI. Enantioselective cationic cyclopolymerization of divinyl ethers with chiral 10-camphorsulfonic acid/zinc chloride initiating system

Cyclopolymerization of benzaldehyde divinyl acetal ( 1 ) and 1,2-divinyloxybenzene ( 4 ) was carried out using (+)- or (−)-camphorsulfonic acid [(+)- or (−)- 2 ]/ZnCl₂ initiating system. Polymer 3 obtained from monomer 1 consisted essentially of cyclic repeating units, whereas polymer 5 from 4 possessed a small amount of residual vinyloxy groups. Both polymers 3 and 5 using (+)- 2 /ZnCl₂ showed optical activity with a negative sign of optical rotation. The molar optical rotation values of polymer 3 using ZnCl₂ · OEt₂ were larger than those using ZnCl₂. The CD spectra of the polymer with [Φ] = −30.1° ((−)- 3 ) and (4S,6S)-4,6-dimethyl-2-phenyl-1,3-dioxane showed a negative Cotton effect at 210 nm, whereas the polymer with [Φ] = +24.1° ((+)- 3 ) and (4R,6R)-4,6-dimethyl-2-phenyl-1,3-dioxane had mirror image CD curves with a positive Cotton effect at 210 nm. The absolute configurations of the major chiral cyclic units in (−)- and (+)- 3 were the SS- and RR-forms, respectively. © 1997 John Wiley & Sons, Inc.     

Remote substituent effect favoring the formation of syn-adducts in the chelation controlled radical reactions of γ-benzyloxy-α-methylenecarboxylic acid esters

The chelation controlled radical reactions of ethyl γ-benzyloxy-α-methylenecarboxylates bearing a bulky γ-substituent, such as CHMe₂, CHPh₂, c-C₆H₁₁ and CH(Ph)OTBDMS, with alkyl iodides gave the syn-adducts with high diastereoselectivities. However, the diastereoselectivity for the substrates bearing a γ-substituent CH(i-Pr)OTBDMS depended critically on the configuration of the substituent; the substrate bearing the OTBDMS group anti to the γ-benzyloxy group showed poor diastereoselectivity, but its diastereomer gave syn-adduct exclusively. The high syn-selectivitiy is referred to the H-atom transfer to the outside face of radical center in the sharply folded seven-membered chelate intermediate bearing the ethoxy group with Z-geometry. The corner flapping of the radical center atom of the global minimum energy conformer generates a local minimum conformer and the H-atom transfer to the outside face of the radical center of the newly formed structure gives the anti-adduct. The poor diastereoselectivity is due to the very small energy difference between the two conformers and consequently both the syn- and anti-adducts are yielded in nearly equal amounts.     

Asymmetric induction by helical poly(amino acid)s in cyanosilylation of aldehydes

It was first demonstrated that helical poly(amino acid)s have an ability to induce enantioselectivity in the cyanosilylation of aldehydes. The helicity of poly(amino acid)s and the N-terminal amino group were essential for the enantioinduction of the reaction.     

A new strategy in enantioselective intramolecular hetero Diels-Alder reaction: catalytic double asymmetric induction during the tandem transetherification-intramolecular hetero Diels-Alder reaction of methyl (E)-4-methoxy-2-oxo-3-butenoate with rac-6-methyl-5-hepten-2-ol

An efficient catalytic double asymmetric induction during the tandem transetherification-intramolecular hetero Diels-Alder reaction has been developed. The enantioselective tandem reaction of methyl (E)-4-methoxy-2-oxo-3-butenoate with rac-6-methyl-5-hepten-2-ol has been achieved to provide methyl (2R,4aS,8aR)-3,4,4a,8a-tetrahydro-2,5,5-trimethyl-2H,5H-pyrano[4,3-b]-pyran-7-carboxylate in good yield with effective kinetic resolution (up to 95% selectivity), high diastereoselectivity (up to 92% de), and high enantioselectivity (up to 97% ee) in the presence of (S,S)-tert-Bu-bis(oxazoline)-Cu(SbF₆)₂ and 5 Å molecular sieves.