5-{[(4′-正戊基氧-4-联苯基基)羰基]氧}-1-戊炔的相转变与相结构

采用差示扫描量热(DSC)、一维(1D)广角X射线衍射(WAXD)、热台偏光显微镜(PLM-hotstage)等研究手段对含联苯液晶基元的侧链液晶聚炔单体5-{[(4′-正戊基氧-4-联苯基基)羰基]氧}-1-戊炔(A3EO5)的本体相转变和相结构进行了研究.DSC和1D-WAXD实验结果表明,A3EO5在升温和降温过程中均呈现四个相转变过程,形成双向性液晶.样品从各向同性态降温至室温过程中,首先形成近晶A相,随后进入层内排列具有准长程有序的近晶B相,继续降温将形成层内为正交排列的近晶E相,在此之后样品进入晶相.PLM结果指出样品在各向同性态降温过程中分别形成球状织构、角锥织构和同心圆弧织构.     

Fluorescence-modified superparamagnetic nanoparticles: intracellular uptake and use in cellular imaging

This report describes the preparation and characterization of new magnetic fluorescent nanoparticles and our success in using them to label living cells. The bifunctional nanoparticles possess a magnetic oxide core composed of a dimercaptosuccinic acid (DMSA) ligand at the surface and a covalently attached fluorescent dye. The nanoparticles exhibited a high affinity for cells, which was demonstrated by fluorescence microscopy and magnetophoresis. Fluorescence microscopy was used to monitor the localization patterns of magnetic nanoparticles associated with cells. We observed two types of magnetic labeling: adsorption of the nanoparticles on the cell membrane (membranous fluorescence) and internalization of the nanoparticles inside the cell (intracellular vesicular fluorescence). After internalization, nanoparticles were confined inside endosomes, which are submicrometric vesicles of the endocytotic pathway. We demonstrated that endosome movement could be piloted inside the cell by external magnetic fields such that small fluorescent chains of magnetic endosomes were formed in the cell cytoplasm in the direction of the applied magnetic field. Finally, by measuring the critical cellular magnetic load (quantitated by magnetophoresis), we have demonstrated the potential of this new magneto-fluorescent nanoagent for medical use.     

Boosting Non‐Radiative Decay to Do Useful Work: Development of a Multi‐Modality Theranostic System from an AIEgen

The efficient utilization of energy dissipating from non‐radiative excited‐state decay of fluorophores was only rarely reported. Herein, we demonstrate how to boost the energy generation of non‐radiative decay and use it for cancer theranostics. A novel compound (TFM) was synthesized which possesses a rotor‐like twisted structure, strong absorption in the far red/near‐infrared region, and it shows aggregation‐induced emission (AIE). Molecular dynamics simulations reveal that the TFM aggregate is in an amorphous form consisting of disordered molecules in a loose packing state, which allows efficient intramolecular motions, and consequently elevates energy dissipation from the pathway of thermal deactivation. These intrinsic features enable TFM nanoparticles (NPs) to display a high photothermal conversion efficiency (51.2 %), an excellent photoacoustic (PA) effect, and effective reactive oxygen species (ROS) generation. In vivo evaluation shows that the TFM NPs are excellent candidates for PA imaging‐guided phototherapy.     

A new approach to modelling Kelvin probe force microscopy of hetero-structures in the dark and under illumination

A numerical method is proposed to model Kelvin probe force microscopy of hetero-structures in the dark and under illumination. It is applied to FTO/TiO₂ and FTO/TiO₂/MAPbI₃ structures. The presence of surface states on the top of the TiO₂ layers are revealed by combining theoretical computation and experimental results. Basic features of Kelvin probe force microscopy under illumination, namely surface photovoltage, are simulated as well. The method paves the way toward further investigations of more complicated optoelectronic devices.     

Photoluminescent properties and electronic structures of monosubstituted polyacetylenes: poly{n-[((4′-cyano-4-biphenylyl)oxy)carbonyl]-1-alkynes}

Poly{n-[((4′-cyano-4-biphenylyl)oxy)carbonyl]-1-alkynes} (PAnCN, where n=2, 8), which is a class of monosubstituted polyacetylenes with biphenyl mesogens and cyano tails in their pendants, can emit strong deep-blue photoluminescence (PL). In this paper we have investigated their optical absorptions, PL evolutions with excitation power and excitation wavelength, electronic structures, and the electric-field effect on the PL of a moderately concentrated PAnCN solution that had been treated by electric fields. Having been treated by an electric-field pulse (6×10⁵ V/m) for about 3 s, the originally featureless PL spectrum of the PAnCN solution becomes structured and transient, which evolves with time and external electric field. Our results have demonstrated that both the absorption and the deep-blue PL originate from the biphenyl mesogens in the side chains rather than from the distorted backbones.     

Synthesis of Co2Pt, Co2Pd and MoPd2 mixed-metal clusters with the P–N–P assembling ligands (Ph2P)2NH (dppa) and (Ph2P)2NMe (dppaMe). Crystal structure of [Co2Pt(μ3-CO)(CO)6(μ-dppa)]

Heterometallic triangular platinum–cobalt, palladium–cobalt and palladium–molybdenum clusters stabilized by one or two bridging diphosphine ligands such as Ph₂PNHPPh₂ (dppa) or (Ph₂P)₂NMe (dppaMe) or by mixed ligand sets Ph₂PCH₂PPh₂ (dppm)/dppa have been prepared with the objectives of comparing the stability and properties of the clusters as a function of the short-bite diphosphine ligand used and of the metal carbonyl fragment they contain. Ligand redistribution reactions were observed during the purification of [Co₂Pd(μ₃-CO)(CO)₄(μ-dppa)(μ-dppm)] (4) by column chromatography with the formation of [Co₂Pd(μ₃-CO)(CO)₄(μ-dppm)₂] and the dinuclear complex [(OC)₂ Cl] (5). The latter was independently prepared by reaction of [Pd(dppa-P,P′)₂](BF₄)₂ with Na[Co(CO)₄]. Attempts to directly incorporate the ligand (Ph₂P)₂N(CH₂)₃Si(OMe)₃ (dppaSi) into a cluster or to generate it by N-functionalization of coordinated dppa were unsuccessful, in contrast to results obtained recently with related clusters. The crystal structure of [Co₂Pt(μ₃-CO)(CO)₆(μ-dppa)] (1) has been determined by X-ray diffraction.     

Aggregation-induced emission and aggregation-promoted photochromism of bis(diphenylmethylene)dihydroacenes

Reported herein is a new class of pure polycyclic hydrocarbon molecules, designed through a novel aggregation-induced emission (AIE) strategy, with unexpected photochromic properties. The restriction of intramolecular motion was found as a comprehensive mechanism for the AIE effect. The photochromism mechanism study revealed that the photocyclization reaction of cis-stilbene, the molecular conformation in the single crystal and the tetracene backbone should contribute to the unique photo behavior. In particular, the fast responsive, photo-reversible and thermo-irreversible photochromic effect facilitated in the solid state opens a new field of aggregation-promoted photochromism.     

Numerical simulations of the polymerization reaction of deuterated diacetylene 2,4‐hexadiynylene bis(p‐toluenesulfonate) crystal

In this paper, we developed two types of programs in order to simulate the polymerization reaction of a fully deuterated crystal of diacetylene 2,4‐hexadiynylene bis(p‐toluenesulfonate) (pTS‐D). The first simulation is based on a modification of Baughman's model, a classical model for simulating the polymerization of diacetylene crystals. The agreement between the simulated and experimental results concerning the reaction kinetics is satisfactory. With this simulation algorithm, we take into account the experimental observation that the polymerization of pTS‐H and pTS‐D crystals is really a random process of formation of polymer chains along the crystallographic axis b . The second simulation is based on the Monte Carlo method, which permits not only to simulate the kinetics of the reaction, but also the chain‐length distribution in the hydrogenated and deuterated compounds. These two types of simulations were already developed for the hydrogenated crystal of diacetylene, named pTS‐H. Two main modifications are applied in the case of pTS‐D for taking into account experimental results: in the first the rate constants of chain‐terminating microscopic processes are different in pTS‐H and pTS‐D which must be considered. The second modification concerns the evolution of the lattice deformation during the course of polymerization. The experimental variation of the b parameter as a function of polymer content X in pTS‐D is different from that in pTS‐H; this result is important to consider when calculating the activation energy of the initiation and propagation microscopic processes.     

Silole-containing linear and hyperbranched polymers: synthesis,thermal stability,light emission,nano-dimensional aggregation,and optical power limiting

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 (M_w 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.