Linear polyacetylenes and hyperbranched polyphenylenes carrying 1,2,3,4,5-pentaphenylsilolyl (PS) pendants are designed and synthesized. Homo-polymerization of HC≡CPS, HC≡C(CH2)9OPS, and C6H5C≡C(CH2)9OPS and (co)polycyclotrimerization of (HC≡C)2PS with 1-octyne are effected by NbCl5-, WCl6-, MoCl5-, and TaCl5-based catalysts. High molecular weight linear ( 1-3 ) and hyperbranched polymers (6) are obtained in high yields (Mw up to ∼70 × 103 and yield up to 85%). All the polymers are thermally stable, losing little weight when heated to 350°C. Whereas all the polymers emit faint light when molecularly dissolved, polymers 2 , 3 , and 6 become emissive when aggregated in poor solvents or when cooled to low temperatures. Restricted intramolecular rotations of the phenyl rings upon the axes of the single bonds linked to the silole cores may be responsible for the aggregation- or cooling-induced emission. A multilayer electroluminescent device using 3 as an active layer emits a blue light of 496 nm with maximum brightness, current efficiency, and external quantum yield of 1118 cd/m2, 1.45 cd/A, and 0.55%, respectively. Polymers 6 are non-linear optically active and strongly attenuate the optical power of intense laser pulses, whose optical limiting performances are superior to that of C60, a best-known optical limiter. 相似文献
The European Physical Journal C - We study an extension of the Standard Model that addresses the hints of lepton flavour universality violation observed in $$B\rightarrow K^{(*)} l^+l^-$$ decays at... 相似文献
Aggregation‐induced emission (AIE) describes a photophysical phenomenon in which molecular aggregates exhibit stronger emission than the single molecules. Over the course of the last 20 years, AIE research has made great strides in material development, mechanistic study and high‐tech applications. The achievements of AIE research demonstrate that molecular aggregates show many properties and functions that are absent in molecular species. In this review, we summarize the advances in the field of AIE and its related areas. We specifically focus on the new properties of materials attained by molecular aggregates beyond the microscopic molecular level. We hope this review will inspire more research into molecular ensembles at and beyond the meso level and lead to the significant progress in material and biological science. 相似文献
Pathogenic bacteria infections, especially multidrug resistant bacteria infections have aroused worldwide attention due to their severe threats to human beings. Thus, the development of highly effective antibacterial reagents is very important. However, the design of antimicrobials is still quite challenging for the lack of a universal design strategy. Here, a synergistic manipulation strategy of dipole-dipole and anion-π+ interaction is proposed for constructing highly efficient antimicrobials with aggregation-induced emission (AIE) feature. Firstly, four anion-π+-type AIE luminogens were designed and synthesized. Due to the electron-donating and hydrophilic characteristic of methoxy groups, 3MOTPO containing three methoxy groups showed the largest dipole moment (5.06 Debye) and dual anion-π+ interactions in the solid state. Driven by both dipole-dipole and anion-π+ interactions, 3MOTPO showed the strongest bacterial binding ability and the best antibacterial activities (MIC90=3.76 μM). The work offers a deep insight into the rational design of highly efficient antimicrobials for luminescence-guided antibacterial study. 相似文献
New imidazole‐functionalized disubstituted polyacetylene was synthesized by utilizing the postfunctional strategy. In addition, its ability to sense copper ions and α‐amino acids by fluorescence quenching has been studied. The quenching of the fluorescence of the imidazole‐functionalized disubstituted polyacetylene was observed at a very low level of Cu2+ (7.0 × 10−7 mol · L−1). The fluorescent intensity decreased rapidly upon the increase of the concentration of the added solution of Cu2+. It was expected that the addition of α‐amino acids to the solution of the polyacetylene/Cu2+ complex could turn on the fluorescence of the polyacetylene, if α‐amino acids could remove the copper ions from the complex. Glycine, was used for testing: upon the addition of glycine the quenched fluorescence of P1 turned on immediately. The detection limit was as low as 6.0 × 10−5 mol · L−1.
Two-dimensional (2D) 59Co correlation spectroscopy (COSY)/double-quantum-filtered (DQF)COSY experiments are reported for three tetrahedral mixed-metal clusters HFeCo3(CO)11L with L = PPh3, P(OMe)3, and PCy3 (Cy = cyclohexyl) in which the L-substituted Co center is chemically different from the other two. The 2D 59Co COSY and DQFCOSY NMR spectra of these clusters in solution prove the existence of a scalar coupling constant between the 59Co nuclei. To determine this value for each cluster, 2D 59Co COSY and DQFCOSY NMR spectra have been simulated by numerical density-matrix calculations. The predicted spectra mimic well the features of the experimental spectra if a scalar coupling is introduced between the Co nuclei. It was initially observed that the scalar coupling constants between the Co nuclei obtained from the 2D COSY and DQFCOSY NMR spectra differed significantly. In contrast to the 2D COSY spectra, the diagonal and cross peaks are of comparable intensity in the 2D DQFCOSY spectra, which leads to a considerable increase in the accuracy of the determination of the scalar coupling constant. 相似文献
Functional phenylacetylene derivatives containing l-alanine and l-leucine moieties with chiral menthyl and achiral n-octyl terminal groups {HC[triple bond]C-C6H4-p-CONHCH(R)CO2R': R = CH3, R'= (-)-(1R,2S,5R)-menthyl [1(-)]; R = CH2CH(CH2)3, R' = (-)-(1R,2S,5R)-menthyl [2(-)]; R'= CH2CH(CH2)3, R' = (+)-(1S,2R,5S)-menthyl [2(+)]; R'= CH2CH(CH2)3, R' = (CH2)7CH3 (2o)} are synthesized. Polymerizations of the acetylene monomers are effected by organorhodium catalysts, giving corresponding polymers P1(-), P2(-), P2(+), and P2o of high molecular weights (Mw up to 1.2 x 10(6)) in high yields (up to 89%). The polymers are thermally stable (Td >or= 300 degrees C) and soluble in common organic solvents. The polymer structures are characterized by IR, NMR, UV, and CD spectroscopies. Intense CD signals are observed in the visible spectral region, indicating that the polymer chains are taking a helical conformation with an excess of preferred handedness. The backbone conjugation and chain helicity of the polymers can be tuned by changing their molecular structures [(a)chiral pendant groups] and by applying external stimuli (solvent and pH). Addition of trifluoroacetic acid to the polymer solutions decreases their molar ellipticities and enhances their backbone conjugations, inducing a halochromism with a continuous and reversible color change (yellow <==> red). 相似文献
Biphenyl (Biph)-containing 1-phenyl-1-octynes and their polymers are synthesized, and the effects of functional bridge groups on the mesomorphic and optical properties of the polymers are studied. The nonmesomorphic disubstituted acetylene monomers (C6H13)C[triple bond]C(C6H4)O(CH2)12O-Biph-OC7H15 (1), (C6H13)C[triple bond]C(C6H4)O(CH2)11OOC-Biph-OC7H15 (2), and (C6H13)C[triple bond]C(C6H4)CO2(CH2)12OOC-Biph-OC7H15 (3) are prepared by multistep reaction routes and converted into their corresponding polymers P1-P3 by a WCl6-Ph4Sn catalyst. The structures and properties of the polymers are characterized and evaluated by NMR, TGA, DSC, POM, XRD, UV, and PL analyses. The mesogenic pendants have endowed the polymers with high thermal stability (> or =400 degrees C). While P1 exhibits no liquid crystallinity, P2 and P3 form enantiotropic S(A) phase with a monolayer structure. Upon photoexcitation, the polymers emit blue and blue-green lights of 460 and 480 nm, respectively, in THF with quantum efficiencies larger than 30%. UV irradiation of a thin film of P2 through a mask oxidizes and quenches the light emission of the exposed regions, generating a two-dimensional luminescent photoimage. 相似文献
By employing a new synthetic strategy, a series of oligomers and a polymer composed of different number of tetraphenylethene and triphenylamine units was designed and synthesised. The optical physics properties and electroluminescence behaviours were studied comparatively. All the molecules demonstrate an aggregation‐induced emission (AIE) phenomenon and bear very high quantum yields in the solid state. The emission wavelengths and quantum efficiencies alternate with the change of the molecular configurations and achieve their maximum at the largest oligomer. The thermal stabilities also become higher along with the increase in the molecular weight. The molecules have suitable HOMO levels that match the work function of the indium tin oxide (ITO) anode. They can act as both light‐emitting and hole‐transporting materials in OLEDs. Thus the present strategy combines the intrinsic emissive nature of AIE materials and the good hole‐transport capability of aromatic amines, thereby achieving a win–win for both optical and electrical properties. 相似文献