Liquid crystal properties of a mesogenic polyacetylene, poly(11-[(4'-heptoxy-4-biphenylyl)carbonyloxy]-1-undecyne)

The liquid crystalline properties of a mesogenic poly(1-alkyne) and the corresponding monomer were studied using transmission electron microscopy, X-ray diffraction, polarizing optical microscopy and differential scanning calorimetry. The monomer exhibits a monotropic smectic A phase and a metastable crystalline phase. The rigid polymer backbones do not prevent the mesogenic moieties from packing into smectic A and B phases in the temperature ranges 127.6-74.1°C and 74.1°C-room temperature, respectively, on cooling from the isotropic melt.     

A macro-element to simulate 3D soil–structure interaction considering plasticity and uplift

In structural engineering, soil–structure interaction (SSI) is an important phenomenon that has to be taken into account. This paper presents a 3D non-linear interface element able to compute SSI based on the “macro-element” concept. The particularity of the macro-element lies in the fact that the movement of the foundation is entirely described by a system of generalised variables (forces and displacements) defined at the foundation centre. The non-linear behaviour of the soil and the uplift mechanism of the foundation are reproduced using the plasticity theory. The failure surface is defined using an adequate overturning mechanism. Coupling of the different mechanisms is straight forward following the theory of multi-mechanisms. The macro-element is able to simulate the 3D behaviour of a rigid shallow foundation of circular, rectangular or strip shape, submitted to cyclic loadings. It is implemented into FEDEASLab, a finite element MATLAB toolbox. Comparisons with experimental results under cyclic loadings show the performance of the approach.     

Synthesis and light-emitting properties of disubstituted polyacetylenes carrying chromophoric naphthylethynylphenyl pendants

Poly(1-phenyl-1-alkyne)s bearing chromophoric pendants and containing alkyl spacers (-{(C 6H 5)CC[(CH 2) m OCOC 6H 4CCNp]} n - [P 1( m) ( m = 3, 4, 9); Np = 1-naphthyl]) were synthesized, and the effects of structural variations on the optical properties, especially electroluminescence, of the polymers were investigated. The monomers were prepared in high yields by esterification and coupling reactions of n-phenyl-( n - 1)-alkyn-1-ols. Selective polymerizations of the 1-phenyl-1-alkyne unit of the monomers were effected by WCl 6-Ph 4Sn catalyst, affording polymers with high molecular weights ( M w up to 63 000) in high yields (up to 83%). Structures and properties of the polymers were characterized and evaluated by IR, NMR, TGA, UV, PL, and EL analyses. All the polymers are thermally very stable, losing almost no weight when heated up to 400 degrees C. Photoexcitation of the polymer solutions induces strong blue light emission at 460 nm, with quantum yields up to 98%. No aggregation quenching was observed when the polymers were fabricated into solid films. Multilayer EL devices with the configuration of ITO/P 1( m):PVK/BCP/Alq 3/LiF/Al were fabricated, which emitted blue light with luminance up to 498 cd/m (2). The device performance varied with the spacer length ( m), with P 1(4) giving the highest external quantum efficiency of 0.47%. The value was further enhanced to 0.86% by optimizing the layer thickness and inserting a hole-injection layer.     

Metallized hyperbranched polydiyne: a photonic material with a large refractive index tunability and a spin-coatable catalyst for facile fabrication of carbon nanotubes

A cobalt-containing hyperbranched polydiyne shows refractive indexes (n) as high as 1.713-1.813 in the long wavelength region, which can be tuned to a large extent (Deltan up to approximately 0.048) by UV irradiation; the polymer can also function as a spin-coatable catalyst for the growth of carbon nanotubes.     

Time-Dependent Photodynamic Therapy for Multiple Targets: A Highly Efficient AIE-Active Photosensitizer for Selective Bacterial Elimination and Cancer Cell Ablation

Pathogen infections and cancer are two major human health problems. Herein, we report the synthesis of an organic salt photosensitizer (PS), called 4TPA-BQ, by a one-step reaction. 4TPA-BQ presents aggregation-induced emission features. Owing to the aggregation-induced reactive oxygen species generated and a sufficiently small ΔE_ST, 4TPA-BQ shows a satisfactorily high ¹O₂ generation efficiency of 97.8 %. In vitro and in vivo experiments confirmed that 4TPA-BQ exhibited potent photodynamic antibacterial performance against ampicillin-resistant Escherichia coli with good biocompatibility in a short time (15 minutes). When the incubation duration persisted long enough (12 hours), cancer cells were ablated efficiently, leaving normal cells essentially unaffected. This is the first reported time-dependent fluorescence-guided photodynamic therapy in one individual PS, which achieves ordered and multiple targeting simply by varying the external conditions. 4TPA-BQ reveals new design principles for the implementation of efficient PSs in clinical applications.     

High hole mobility of 1,2-bis[4'-(diphenylamino)biphenyl-4-yl]-1,2-diphenylethene in field effect transistor

Triphenylamine-functionalized tetraphenylethene shows aggregation-induced emission feature with unity solid-state fluorescence efficiency. Its amorphous film can function in a p-type FET device with field effect mobility up to 2.6 × 10(-3) cm(2)/Vs.     

Aggregation-induced emission

Luminogenic materials with aggregation-induced emission (AIE) attributes have attracted much interest since the debut of the AIE concept in 2001. In this critical review, recent progress in the area of AIE research is summarized. Typical examples of AIE systems are discussed, from which their structure-property relationships are derived. Through mechanistic decipherment of the photophysical processes, structural design strategies for generating new AIE luminogens are developed. Technological, especially optoelectronic and biological, applications of the AIE systems are exemplified to illustrate how the novel AIE effect can be utilized for high-tech innovations (183 references).     

Efficient Polymerization of Azide and Active Internal Alkynes

The 1,3‐dipolar cycloaddition of azides and active internal alkynes has been well studied, but is rarely utilized as a tool for polymer preparation. In this work, an efficient polymerization route is developed. Polycycloaddition of diazide ( 4 ) and bis(benzoylethynyl)‐benzenes and ‐butane ( 3 ) at elevated temperature has produced the first examples of soluble 1,4,5‐trisubstituted polytriazoles P I with satisfactory molecular weights (M _w up to 16 400) in excellent yields (up to 98.6%). All the obtained polymers are thermally stable, losing merely 5% of their weights at temperatures higher than 367 °C. They exhibit higher refractive indices than some commercial plastics and can be crosslinked upon UV irradiation to generate a 3D photopattern with high resolution. The metal‐free feature of such a methodology offers a facile tool to prepare functional materials free from the contamination of metal species.     

Lekner summations and Ewald summations for quasi-two-dimensional systems

The purpose of this work is to carry out a comparison between the Ewald quasi-2D and Lekner summation methods. These methods were derived to treat the long-range electrostatic interactions in systems periodic in two directions, but bound in the third. The comparison is performed by Monte Carlo simulations on a very simple system, a bilayer of point ions; samplings of the phase space, average energies and structure functions are compared. When correctly implemented, the Lekner summation method is found to be in close agreement with the Ewald quasi-2D method; otherwise, a very complicated bias may plague computations.     

Conjugated hyperbranched poly(aryleneethynylene)s: synthesis, photophysical properties, superquenching by explosive, photopatternability, and tunable high refractive indices

Triphenylamine (TPA)-based conjugated hyperbranched poly(aryleneethynylene)s (PAEs), hb-P1/2, hb-P1/3, and hb-P1/4, were synthesized with high molecular weights and good solubilities through Sonogashira coupling reactions. These PAEs exhibited outstanding thermal stabilities and different emission behaviors. Tetraphenylethene (TPE)-containing hb-P1/2 fluoresced faintly in THF, although its light emission was enhanced by aggregate formation in aqueous media or in thin films, thereby exhibiting an aggregation-induced emission-enhancement (AIEE) effect. Whereas 1,1,2,3,4,5-hexaphenylsilole (HPS)-bearing hb-P1/3 showed no significant change in emission intensity with increasing water content in aqueous media, hb-P1/4, which consisted of TPA-fluorenone donor-acceptor groups, presented almost identical absorptions, but both positive and negative solvatochromic emissions in various solvents. A superquenching effect was observed in the picric-acid-detection process by using nanosuspensions of hb-P1/2. All of the polymers possessed good film formability. UV irradiation of the thin films induced simultaneous photobleaching and cross-linking, thus making them applicable in the fabrication of 2D and 3D patterns. Furthermore, the polymer films also showed high refractive indices, which were tunable upon exposure to UV light.