Optical Properties and Photo‐Oxidation of Tetraphenylethene‐Based Fluorophores

We report the optical properties of tetraphenylethene (TPE) and other TPE derivatives functionalised with an octyl group (TPE‐OCT) and polyethyleneglycol group (TPE‐PEG) in the side chain. We compared TPE‐OCT and TPE‐PEG with TPE in both organic solvents and under aqueous conditions. All materials exhibit aggregation‐induced emission, however, uncommonly, TPE‐PEG seems to aggregate in aqueous solution with enhanced photoluminescence quantum efficiency (PLQE) relative to that in organic solvents. All three materials can be photo‐oxidised in solution to their diphenylphenanthrene derivative by irradiation with UV light (at both ≈1 and ≈5 mW cm^?2), with a subsequent enhancement in PL efficiency. The electron‐donating ether group increases the rate of oxidation relative to bare TPE and also photo‐oxidation was shown to be solvent and concentration dependent. Finally, photo‐oxidation was also demonstrated in the aggregate state.     

Improved Resolution of Hydrophobic Penicillin-binding Proteins and Their Covalently Linked Complexes on a Modified C18 Reversed Phase Column

ABSTRACT

Hydrophobic proteins have proven to be difficult to separate chromatographically. The use of a C18 reversed phase column with embedded polar groups showed improved separation and recovery of the hydrophobic, membrane associated, penicillin-binding proteins of Bacillus subtilis and their covalently linked complexes. The covalently linked complexes were generated by a time course reaction of the non-covalently associated complexes in the intact cell with the paired group specific reagent, cyanogen (C₂N₂).     

中间嵌段为亲水性的BAB型三嵌段共聚物水溶液中初级聚集体的二次聚集行为研究

采用TEM和AFM研究了PS(聚苯乙烯)₄₃-b-PEO(聚氧乙烯)₄₅-b-PS₄₃和PS₃₉-b-P4VP(聚4-乙烯基吡啶)₉₈-b-PS₃₉三嵌段共聚物在水介质中的球形胶束、囊泡和蠕虫状胶束之间的二次聚集行为.实验发现,初级聚集体的二次聚集具有不同的复杂程度.对称性的初级聚集体,如球形胶束和囊泡,其二次聚集表现出球形对称性;而非对称性初级聚集体(如蠕虫状胶束)二次聚集开始倾向于非对称性.BAB型的嵌段设计有利于初级聚集体的二次聚集发生.     

稳态荧光探针法测定临界胶束聚集数

以芘为荧光探针、二苯甲酮为猝灭剂,用稳态荧光探针法测定了SDS和AS的胶束聚集数(Nm).以芘的饱和水溶液为溶剂配制表面活性剂溶液,二苯甲酮的适宜浓度取小于1.00 mmol•L－1时,可以获得满意的实验结果.当表面活性剂溶液浓度为5～9倍cmc时,Nm随表面活性剂浓度增大而线性增大,而随温度的变化略有波动.cSAA=cmc时,Nm值为一本征值,定义为临界胶束聚集数[Nm].[Nm]值可从Nm－cSAA实验曲线外延得到.25℃时SDS的临界胶束聚集数[Nm]为57;40℃时SDS的[Nm]为49,AS的[Nm]为55.     

Aggregation-Enhanced Emission and Thermally Activated Delayed Fluorescence of Derivatives of 9-Phenyl-9H-Carbazole: Effects of Methoxy and tert-Butyl Substituents

Derivatives of 9-phenyl-9H-carbazole were synthesized as efficient emitters exhibiting both thermally activated delayed fluorescence and aggregation-induced emission enhancement. Effects of methoxy and tert-butyl substituents at the different positions of carbazolyl groups on the properties of the emitters were studied. Depending on the substitutions, photoluminescence quantum yields (PLQY) of non-doped solid films of the compounds ranged from 17 % to 53 % which were much higher than those observed for the solutions in low-polarity solvent toluene. Compounds substituted at C-3 and C-6 positions of carbazole moiety by methoxy- and tert-butyl- groups showed the highest solid-state PLQY. Ionization potentials of the studied derivatives in solid-state were found to be in the short range of 5.75–5.89 eV. Well-balanced hole and electron mobilities were detected for tert-butyl-substituted compound. They exceeded 10⁻⁴ cm² (V×s)⁻¹ at electric fields higher than 3×10⁵ V cm⁻¹. Two compounds with the highest solid-state PLQYs showed higher efficiencies in non-doped organic light-emitting diodes than in the doped devices. Maximum external quantum efficiency of 7.2 % and brightness of 15000 cd m⁻² were observed for the best device.     

Exploring the relevance of thiophene rings as bridge unit in acceptor‐bridge‐donor dyes on self‐aggregation and performance in DSSCs

The possibility of dye charge recombination in DSSCs remains a challenge for the field. This consists of: (a) back‐transfer from the TiO₂ to the oxidized dye and (b) intermolecular electron transfer between dyes. The latter is attributed to dye aggregation due to dimeric conformations. This leads to poor electron injection which decreases the photocurrent conversion efficiency. Most organic sensitizers are characterized by an Acceptor‐Bridge‐Donor ( A ‐Bridge‐ D ) arrangement that is commonly employed to provide charge separation and, therefore, lowering the unwanted back‐transfer. Here, we address the intermolecular electron transfer by studying the dimerization and photovoltaic performance of a group of A ‐Bridge‐ D structured dyes. Specifically, eight famous sulfur containing π‐bridges were analyzed ( A and D remained fixed). Through quantum mechanical and molecular dynamics approaches, it was found that the formation of weakly stabilized dimers is allowed. The dyes with covalently bonded and fused thiophene rings as Bridges, 6d and 7d as well as 8d with a fluorene, would present high aggregation and, therefore, high probability of recombination processes. Conversely, using TiO₂ cluster and surface models, delineated the shortest bridges to improve the adsorption energy and the stability of the system. Finally, the elongation of the bridge up to 2 and 3 units and their photovoltaic parameters were studied. These results showed that all the sensitizers are able to provide similar photocurrent outcomes, regardless of whether the bridge is elongated. © 2017 Wiley Periodicals, Inc.     

Synthesis of SiO2@SiO2 core-shell microspheres using urea-formaldehyde polymers as the templates for fast separation of small solutes and proteins

The monodisperse superficially porous core-shell silica microspheres (CSSMs) with controllable shell thickness and pore size were synthesized by an improved polymerization-induced colloid aggregation (PICA) approach for fast separation of small solutes and proteins.     

Amyloid‐β Peptide Induces Prion Protein Amyloid Formation: Evidence for Its Widespread Amyloidogenic Effect

Transmissible spongiform encephalopathy is associated with misfolding of prion protein (PrP) into an amyloid β‐rich aggregate. Previous studies have indicated that PrP interacts with Alzheimer′s disease amyloid‐β peptide (Aβ), but it remains elusive how this interaction impacts on the misfolding of PrP. This study presents the first in vitro evidence that Aβ induces PrP‐amyloid formation at submicromolar concentrations. Interestingly, systematic mutagenesis of PrP revealed that Aβ requires no specific amino acid sequences in PrP, and induces the misfolding of other unrelated proteins (insulin and lysozyme) into amyloid fibrils in a manner analogous to PrP. This unanticipated nonspecific amyloidogenic effect of Aβ indicates that this peptide might be involved in widespread protein aggregation, regardless of the amino acid sequences of target proteins, and exacerbate the pathology of many neurodegenerative diseases.     

肉桂酰酪胺类似物的合成与抗血小板聚集评价

为了探究肉桂酰酪胺的苯环上甲氧基取代、酪胺上羟基和酰胺上胺基被甲基化对衍生物抗血小板聚集活性的影响,以8种苯甲醛衍生物为原料,经过缩合反应及甲基化等反应制得肉桂酰酪胺类似物,经核磁共振波谱仪(NMR)、质谱(MS)、单晶衍射等技术手段表征了目标化合物结构。 基于变温核磁,探讨了化合物4a~4h中旋转异构及酰胺C-N键双键性质对氢核磁谱的影响。 采用Born比浊法对目标化合物进行活性筛选,9个类似物的活性均强于柄果花椒酰胺,特别是化合物2c、4c、4f在200 μmol/L时显示出强的抑制率,分别为50.03%、60.87%、53.33%。 该类化合物的构效关系是4位甲氧基取代对化合物的抗ADP(二磷酸腺苷)诱导血小板聚集活性最为有利,甲基化B环中的羟基和结构中的酰胺氮原子时,在某种程度上可增强化合物活性。     

Small-angle neutron scattering from micelles of alkylpolyoxyethylene sulfate: Effect of chain length

Small-angle neutron scattering (SANS) data have been obtained for (i) a series of solutions of C _m H_2m+1(OCH₂–CH₂)₂SO₄Na, for m=18, 16, and 14; (ii) an approximately 0.07M solution of C₁₄H₂₉(OCH₂–CH₂)₂SO₄Na to which different amounts of NaCl were added; and (iii) a series of solutions of variable concentration of C₁₂H₂₅(OCH₂–CH₂)SO₄Na. The increase of the number of carbon atoms of the hydrocarbon chain produces a noticeable increase of the aggregation number of the micelles, while the salt tolerance decreases with increasing m. All the data can be described in terms of a monodispersed, charged, hard-spheres model interacting via a screened Coulombic potential, except the run at highest salt concentration, for which an ellipsoid model gives better results.