The Sensitized Solid‐Phase Electrochemiluminescence of Electrodeposited Poly‐Luminol/Aniline on AuAg/TiO2 Nanohybrid Functionalized Electrode for Flow Injection Analysis

In this study, a copolymer of luminol with aniline is electrochemically deposited onto the AuAg/TiO₂ nanohybrid functionalized indium tin oxide coated glass. It is used as a reagentless electrochemiluminescent (ECL) electrode for flow‐injection‐analysis (FIA). The properties of this solid phase ECL electrode are characterized by cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy etc. It has stronger ECL emission, sensitive response for target analytes and excellent stability. The so‐prepared ECL electrode shows sensitive response to reactive oxygen species thereafter to be applied for determination of hydrogen peroxide with FIA mode. Under optimized conditions, a mass detection limit of 0.822 pg of hydrogen peroxide was obtained. Thus the hydrogen peroxide residues in samples were detected with satisfactory result.     

Catalytic Asymmetric Formal [3+3] Cycloaddition of an Azomethine Ylide with 3‐Indolylmethanol: Enantioselective Construction of a Six‐Membered Piperidine Framework

A catalytic asymmetric formal [3+3] cycloaddition of 3‐indolylmethanol and an in situ‐generated azomethine ylide has been established to construct a chiral six‐membered piperidine framework with two stereogenic centers. This approach not only represents the first enantioselective cycloaddition of isatin‐derived 3‐indolylmethanol, but also has realized an unusual enantioselective formal [3+3] cycloaddition of azomethine ylide rather than its common [3+2] cycloadditions. Besides, this protocol combines the merits of a multicomponent reaction and organocatalysis, which efficiently assembles a variety of isatin‐derived 3‐indolylmethanols, aldehydes, and amino esters into structurally diverse spiro[indoline‐3,4′‐pyridoindoles] with one all‐carbon quaternary stereogenic center in high yields and excellent enantioselectivities (up to 93 % yield, >99 % enantiomeric excess (ee)). Although the diastereoselectivity of the reaction is generally moderate, most of the diastereomers can be separated by using column chromatography followed by preparative TLC.     

Investigating the effect of mono‐ and multivalent counterions on the conformation of poly(styrenesulfonic acid) by nanopores

Polyelectrolytes are useful materials that have many technical, medical, physiological and biological applications. The properties of polyelectrolytes are determined not only by their chemical composition but also by their conformational states. However, the conformations of polyelectrolytes in solution are very difficult to characterize. Herein, we propose to use a protein nanopore to investigate the effect of mono‐ and multivalent counterions on the conformational changes of a simple polyelectrolyte, sodium poly(styrenesulfonic acid) (NaPSS). High concentration of KCl induced a conformational transition of NaPSS from “swollen random coil” form in low salt concentration to “random coil” form and was evidenced by the changes of the translocation event pattern. Addition of Mg²⁺ in buffer solution did not cause notable changes of NaPSS translocation events, but Dy³⁺ and Y³⁺ were shown to have remarkable effects on the translocation profile of NaPSS. Bridging events caused by Dy³⁺ or Y³⁺ between polyelectrolyte chains largely affected current blockage and dwell time of the translocation events. Our results provide experimental evidence for the classical theories of conformational transitions of polyelectrolytes and may find applications in many other polyelectrolyte‐related researches.     

Interfacial Self‐Assembly of Closely Packed Nanoparticle Arrays of Silica@Multiporphyrin Hybrids as Light‐Sensitizers for Dye Degradation and Viologen Photochromism

Light‐sensitizer functionalized organic–inorganic hybrid materials have attracted much attention owing to their potential applications in the fields of optoelectronics, heterogeneous catalysis, sensors, and nanotechnology. Here, an interfacial self‐assembly of zero‐dimensional (0D) silica@multiporphyrin array nanohybrids and their 3D Langmuir–Blodgett (LB) films is reported. Photoactive tetrapyridylporphyrin (TPyP) was first assembled on the silica nanoparticles’ surfaces via silane, substitution, and coordination reactions to produce nanoSiO₂@(Pd‐TPyP)_n hybrids. Then, the Cd²⁺‐nanoSiO₂@(Pd‐TPyP)_n monolayers and LB films were constructed on the CdCl₂ subphase surface. These monolayers and LB films displayed stronger stability, as well as more uniform and closely packed nanoparticle arrays compared with those prepared on the pure water surface, owing to the formation of strong network‐like Pd‐ and Cd‐TPyP coordination units, which significantly enhanced the nanoparticles’ interaction. Further, compared with that of the 0D nanoSiO₂@(Pd‐TPyP)_n hybrids, the degradation efficiency was nearly 20 times higher when the hybrids’ LB films were used as light‐sensitizers for the photocatalytic degradation of RhB. Finally, flexible photochromic devices were constructed by using the LB films sandwiched between two electrodes, which displayed a reversible photoinduced redox reaction of viologen together with a color change process. Because TPyP was strongly immobilized on the nanoparticles’ surfaces and the particles were connected through the Py‐Pd²⁺‐Py and Py‐Cd²⁺‐Py coordination units with the 3D network‐like architecture, the present nanohybrids and LB films had good stability and reusability.     

Development of dipyridine‐based coordinative polymers for reusable heterogeneous catalysts

Poly(di(pyridin‐2‐yl)methyl acrylate) (PDPyMA), which was obtained by the free radical polymerization of designed coordinative monomer of di(pyridin‐2‐yl)methyl acrylate, is able to coordinate with various metal ions to form heterogeneous catalysts for diverse catalytic reactions. The Pd and Cu complexes supported by PDPyMA were developed for the heterogeneous Suzuki‐Miyaura reaction and Friedel‐Crafts alkylation, respectively. The PDPyMA‐based catalysts showed no significant decline of reactivity after five times recycling. However, the hydrolysis of the PDPyMA backbone under alkaline conditions limited the catalytic efficiency of this heterogeneous catalyst so that the coordinative monomer was redesigned as 1,1‐di(pyridine‐2‐yl)‐2‐(4‐vinylphenyl)ethan‐1‐ol and then 2,2′‐(1‐methoxy‐2‐(4‐vinylphenyl)ethane‐1,1‐diyl)dipyridine (MVPhDPy). With copolymerization of N‐isopropyl acrylamide (NIPAM), the efficiency of polymer‐based heterogeneous catalysts could be further raised, demonstrated by the increased turn over number in the Suzuki‐Miyaura reaction, which approached 5,260 by using the catalyst formed from poly(MVPhDPy‐co‐NIPAM) and Pd(OAc)₂. poly(MVPhDPy‐co‐NIPAM) copolymer, therefore, could be a versatile platform to support different metal ions for various heterogeneous catalytic reactions.     

Oxygen-vacancy-rich phenanthroline/TiO2 nanocomposites: An integrated adsorption,detection and photocatalytic material for complex pollutants remediation

To address the challenge of treating complex pollutants containing heavy metals and organic compounds,a phenanthroline/TiO₂ nanocomposite with rich oxygen vacancy defects was synthesized to integrate the functions of pollutant detection, adsorption, and photocatalytic degradation. The results showed that the nanocomposite could adsorb Cr³⁺and the process could be transduced into a colorimetric signal for qualitative and quantitative detection. The adsorbed heavy metal also ...     

Labeling of diazepam with iodine-131

Diazepam, which aims at benzodiazepine receptors and can be used as a specific SPECT agent has been labeled with [¹³¹I]2-iododiazepam (2-IDZ) was obtained in 50% HCl medium and [¹³¹I]2-iododiazepam (2-IDZ) was prepared by the iodogen method. The products were purified by passing through a Dowex-1 anion-exchange column.     

Micro Salting-Out Assisted Matrix Solid-Phase Dispersion: A Simple and Fast Sample Preparation Method for the Analysis of Bisphenol Contaminants in Bee Pollen

In the present work, a novel sample preparation method, micro salting-out assisted matrix solid-phase dispersion (μ-SOA-MSPD), was developed for the determination of bisphenol A (BPA) and bisphenol B (BPB) contaminants in bee pollen. The proposed method was designed to combine two classical sample preparation methodologies, matrix solid-phase dispersion (MSPD) and homogenous liquid-liquid extraction (HLLE), to simplify and speed-up the preparation process. Parameters of μ-SOA-MSPD were systematically investigated, and results indicated the significant effect of salt and ACN-H₂O extractant on the signal response of analytes. In addition, excellent clean-up ability in removing matrix components was observed when primary secondary amine (PSA) sorbent was introduced into the blending operation. The developed method was fully validated, and the limits of detection for BPA and BPB were 20 μg/kg and 30 μg/kg, respectively. Average recoveries and precisions were ranged from 83.03% to 94.64% and 1.76% to 5.45%, respectively. This is the first report on the analysis of bisphenol contaminants in bee pollen sample, and also on the combination of MSPD and HLLE. The present method might provide a new strategy for simple and fast sample preparation of solid and semi-solid samples.     

Isolation of a novel flavanone 6-glucoside from the flowers of Carthamus tinctorium (Honghua) by high-speed counter-current chromatography

A novel flavanone glycoside, (2S)-4',5,6,7-tetrahydroxyflavavone 6-O-beta-D-glucopyranoside was isolated from the ethyl acetate extract of the flowers of Carthamus tinctorium by high-speed counter-current chromatography (HSCCC). Using an optimized two-phase solvent system composed of ethyl acetate-methanol-water (5:1:5, v/v), target compound (52 mg) with purity of 98.0% was obtained from 2.0 g of sample by HSCCC in seven times run. The structure of the target compound was elucidated by means of spectroscopic methods including IR, MS, 1D and 2D NMR techniques.