The synthesis of polyamine networks using cationic living poly(1-tert-butylaziridine)

Polyamine networks have been synthesized by end-linking bifunctional living poly-TBA with polyfunctional nucleophilic reagents. The bifunctional living poly-TBA was obtained by polymerization of TBA initiated by low molecular weight bifunctional living poly(tetrahydrofuran). The swelling degrees of the networks in several solvents are reported.     

双官能度自由基引发剂应用研究的进展

双官能度引发剂在自由基聚合中的应用不断受到重视，本文介绍了常用的双官能度引发剂，并综述了其在制备嵌段共聚物及引发乙烯类单体（如苯乙烯、氯乙烯、丙烯酰胺等）聚合的研究进展。     

Strategies for the preparation of bifunctional gadolinium(III) chelators

The development of gadolinium chelators that can be easily and readily linked to various substrates is of primary importance for the development high relaxation efficiency and/or targeted magnetic resonance imaging (MRI) contrast agents. Over the last 25 years a large number of bifunctional chelators have been prepared. For the most part, these compounds are based on ligands that are already used in clinically approved contrast agents. More recently, new bifunctional chelators have been reported based on complexes that show a more potent relaxation effect, faster complexation kinetics and in some cases simpler synthetic procedures. This review provides an overview of the synthetic strategies used for the preparation of bifunctional chelators for MRI applications.     

Metal–organic framework based bifunctional oxygen electrocatalysts for rechargeable zinc–air batteries: current progress and prospects

Zinc–air batteries (ZABs) are regarded as ideal candidates for next-generation energy storage equipment due to their high energy density, non-toxicity, high safety, and environmental friendliness. However, the slow oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics on the air cathode limit their efficiency and the development of highly efficient, low cost and stable bifunctional electrocatalysts is still challenging. Metal–Organic Framework (MOF) based bifunctional oxygen electrocatalysts have been demonstrated as promising alternative catalysts due to the regular structure, tunable chemistry, high specific surface area, and simple and easy preparation of MOFs, and great progress has been made in this area. Herein, we summarize the latest research progress of MOF-based bifunctional oxygen electrocatalysts for ZABs, including pristine MOFs, derivatives of MOFs and MOF composites. The effects of the catalysts'' composites, morphologies, specific surface areas and active sites on catalytic performances are specifically addressed to reveal the underlying mechanisms for different catalytic activity of MOF based catalysts. Finally, the main challenges and prospects for developing advanced MOF-based bifunctional electrocatalysts are proposed.

The research progress of MOF-based bifunctional oxygen electrocatalysts for zinc–air batteries is reviewed and the main challenges and prospects for developing advanced MOF-based bifunctional electrocatalysts are proposed.     

Novel Bifunctional Thiolcarboxylic Acid Esters Useful as Crosslinking Agents for Optical Materials

Novel bifunctional thiolcarboxylic acid esters such as thiodimethacrylates have been prepared in good yield by reaction of dimercaptanes with acid chloride in KOHaq and organic solvent system in the presence of phase transfer catalyst under mild reaction conditions. These bifunctional thiomethacrylates are useful as crosslinking agents having high refractive indices.     

Bifunctional Ammonium Salt Catalyzed Asymmetric α‐Hydroxylation of β‐Ketoesters by Simultaneous Resolution of Oxaziridines

Chiral bifunctional urea‐containing ammonium salts were found to be very efficient catalysts for asymmetric α‐hydroxylation reactions of β‐ketoesters with oxaziridines under base‐free conditions. The reaction is accompanied by a simultaneous kinetic resolution of the oxaziridine and a plausible and so far unprecedented bifunctional transition‐state model has been obtained by means of DFT calculations.     

On the Mechanism of Bifunctional Squaramide‐Catalyzed Organocatalytic Michael Addition: A Protonated Catalyst as an Oxyanion Hole

A joint experimental–theoretical study of a bifunctional squaramide‐amine‐catalyzed Michael addition reaction between 1,3‐dioxo nucleophiles and nitrostyrene has been undertaken to gain insight into the nature of bifunctional organocatalytic activation. For this highly stereoselective reaction, three previously proposed mechanistic scenarios for the critical C?C bond‐formation step were examined. Accordingly, the formation of the major stereoisomeric products is most plausible by one of the bifunctional pathways that involve electrophile activation by the protonated amine group of the catalyst. However, some of the minor product isomers are also accessible through alternative reaction routes. Structural analysis of transition states points to the structural invariance of certain fragments of the transition state, such as the protonated catalyst and the anionic fragment of approaching reactants. Our topological analysis provides deeper insight and a more general understanding of bifunctional noncovalent organocatalysis.     

双功能螺吡喃螺噁嗪类光致变色化合物研究进展

光致变色材料在光学镜头、光学信息存储、光分子开关等方面具有广泛的应用.双功能光致变色材料的合成与应用研究越来越受关注.综述了以螺吡喃、螺噁嗪为光致变色基团的双功能光致变色化合体系的研究进展,主要介绍了具有荧光性能、与金属离子络合性能的光致变色体系的研究进展以及应用.     

Electrokinetic studies of cellulosic fibres

Results on surface conductivity of cotton fibres dyed with reactive dyes have been reported. In general the surface conductivity values were higher in alkaline pH, but lower in acidic pH as compared to the neutral pH. This observation has been attributed to the contribution of the functional groups present on the dye molecule reacted with the fibre. Results on the surface conductivity of fibres dyed with mono- and bifunctional reactive dyes suggest that dyes react with the hydroxyl groups of the fibre, and that the bifunctional dye molecule forms a crosslink between two cellulosic chains.     

Recent advances of layered double hydroxides–based bifunctional electrocatalysts for ORR and OER

The oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) have attracted increasing attention for the sake of clean, renewable, and efficient energy technologies in recent years. The design of ORR/OER bifunctional electrocatalysts is a challenging task in the promotion of highly efficient rechargeable metal-air batteries as well as regenerative fuel cells. Owing to the wide adaptability of different types and ratios of metals in the interlayer space as well as the adjustable interlayer distance, composite materials with layered double hydroxides (LDHs) and their derivatives have recently been registered as electrode materials and catalysts supports for various electrochemical reactions. This study examines the recent development of bifunctional electrocatalysts based on LDHs for ORR/OER to expand the application of LDHs in the field of energy storage and conversion. Various bifunctional electrocatalysts associated with LDHs are discussed in detail to improve their performance. Finally, existing problems and future prospects for improving the performance of LDHs bifunctional electrocatalysts are proposed.     

A highly selective bifunctional luminescence probe for potassium and fluoride ions

A novel bifunctional molecule 1 by a combination of 1,3-alternate calix[4]-crown-5 and triarylborane moieties through alkynyl linkers has been designed and synthesized. Compound 1 shows intense fluorescence with a photoluminescence quantum yield of 0.70 in CH(2)Cl(2) solution and can serve as a bifunctional luminescent probe for potassium and fluoride ions with high sensitivity and selectivity.     

Bifunctional magnetic-optical nanocomposites: grafting lanthanide complex onto core-shell magnetic silica nanoarchitecture

A new class of bifunctional architecture combining the useful functions of superparamagnetism and terbium complex luminescence into one material has been prepared via two main steps by a modified St?ber method and the layer-by-layer (LbL) assembly technique. The obtained bifunctional nanocomposites exhibit superparamagnetic behavior, high fluorescence intensity, and color purity. The architecture has been characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), UV-vis absorption and emission spectroscopy, X-ray diffraction, and superconducting quantum interference device (SQUID) magnetometry.     

Asymmetric direct vinylogous carbon-carbon bond formation catalyzed by bifunctional organocatalysts

The bifunctional chiral thiourea-tertiary amine organocatalysts have been applied to a direct asymmetric vinylogous Michael addition of α,α-dicyanoolefins to nitroolefins with 2-10 mol % catalyst loadings. The electronic properties of the thiourea-based catalysts have significant influences on this reaction. Moderate to excellent enantioselectivities (57-95% ee) have been achieved with low to good isolated yields through fine tuning the structures of the bifunctional organocatalysts. Much better ees were obtained for some α,α-dicyanoolefinic substrates compared with that catalyzed by modified cinchona alkaloids.     

The application of thin-layer gel filtration chromatography in the rapid assessment of protein-protein coupling reactions.

The use of enzymes as markers when covalently coupled to various antigens or antibodies has wide application in medical science. A variety of bifunctional reagents has been used to produced the conjugates, and there have been some attempts to investigate the conditions of reaction necessary to obtain good coupling, whilst preserving the biological function of the molecules. The present study describes the influence of coupling conditions on the coupling of a alpha-amylase and albumin by a range of commercially available bifunctional coupling reagents, and the application of thin-layer gel filtration chromatography for the rapid qualitative/semi-quantitative assessment of coupling reactions.     

A bifunctional chelator featuring the DOTAM-Gly-l-Phe-OH structural subunit: en route toward homo- and heterobimetallic lanthanide(III) complexes as PARACEST MRI contrast agents

A new synthesis of a bifunctional chelator possessing DOTAM-Gly-l-Phe-OH and DO3A chelating cages interconnected by an oligoamide chain has been achieved via HBTU-mediated coupling from easily accessible building blocks. Both homo- and heterobimetallic lanthanide(III) complexes derived from this bifunctional chelator have been prepared in moderate yields. The CEST spectrum acquired for homobimetallic Eu³⁺ complex showed this molecule to be a promising PARACEST MRI contrast agent whereas the Eu³⁺/Tm³⁺ heterobimetallic complex lacked a useful CEST signal.     

Free radical telluroacylative addition of telluroesters to terminal alkynes

Vinyl selenides and tellurides are important precursors of many kinds of organic compounds, particular the substituted alkenes that occurred in many biologically active compounds as skeleton structures. Thus the study of vinyl selenides and tellurides has attracted considerable attention in recent years. The bifunctional addition reactions involving selenium and tellurium moieties are the latest methods for preparation of vinyl selenides with various functional groups. Recently we have reported the selenocarbonylation of alkynes with selenoesters catalyzed by cuprous halides. Nevertheless the similar bifunctional addition involving tellurium atoms has not been reported. Considering the C-Te bonds are easier to be broken than corresponding C-Se bonds, the vinyl tellurides containing electron-withdrawing groups may have particular reactivity and application in the preparation of substituted alkenes. Herein we describe the synthesis of β-aryltelluro-α,β-unsaturated ketones via bifunctional addition.     

Bifunctional and monofunctional catalysis in the CNDO/2 approximation: Formamidine acid-base and base catalysed 1,3-proton transfers in propene

The bifunctional acid-base and monofunctional base catalysis by formamidine of 1,3-proton transfer reactions in propene has been studied with the CNDO/2 MO-method. Energy profiles for both types of catalysis were studied, and no reaction intermediate was found in either case. In agreement with orbital correlation considerations, bifunctional catalysis is preferred over monofunctional catalysis. Comparison is made with another reaction in which simultaneous transfer of two protons occurs. The mechanism of bifunctional monofunctional catalysis is discussed.     

金属-空气电池中双功能电催化剂微纳结构设计（英文）

金属-空气二次电池在可再生电能的存储和转换方面具有广阔的应用前景.在金属-空气二次电池的空气侧,放电时发生氧还原反应(ORR),充电时发生氧析出反应(OER).然而,ORR和OER反应的动力学过程缓慢,因此限制了金属-空气二次电池的实际应用.因此,发展高性能ORR和OER电催化剂对金属-空气二次电池的发展尤为重要.目前,大多数的研究集中在ORR或OER的单功能电催化剂上,而关于双功能电催化剂的研究和综述相对较少.两个反应均具有较高的过电位和较缓慢的动力学过程,而且充电过程的高电压会导致ORR催化剂失活,反之亦然.因此,开发针对这两个反应均具有高活性和高稳定性的双功能电催化剂极具挑战性.近年来,研究者对具有低成本和高性能双功能电催化剂进行了探索.这些双功能电催化剂包括碳基材料,过渡金属材料和复合材料.双功能电催化剂可以通过提高本征活性和表观活性两种策略来提高其整体的活性.其中,本征活性与晶体结构和电子结构密切相关,即可以通过调节晶体结构和电子结构来提高其本征活性.例如,可以改变金属-氧键的强度、氧空位浓度等来调变电催化活性.在碳基材料中掺杂杂原子可以改变碳的电荷密度分布,从而实现对电催化活性的提高.此外,其表观活性还可以通过改变形貌并利用协同作用来改善.构建特殊微纳结构是提高电催化活性的最常用策略之一.在这种情况下,电催化剂具有较高的比表面积,大量的活性位点和良好的电子传导性.同时,复合电催化剂组分之间在加速电催化过程中的协同作用不容忽视.本文将聚焦双功能电催化剂的微纳结构设计,并简要讨论了纳米结构的精细调控和对反应机理的认识.我们认为,未来的工作应继续加强ORR和OER的新型双功能电催化剂的开发,发展更多的合成方法对电催化剂的微纳结构进行调变,并对反应机理进行更深入的研究.首先,通过对结构的精细调变提高电催化剂的本征活性和表观活性.此外,通过多种原位表征方法揭示反应机理,这有助于电催化剂的设计和催化活性的进一步提升.基于此,开发出性能优异的双功能电催化剂以加快用于存储和转换可再生能源的可充电金属-空气二次电池的商业化进程.     

A bifunctional anthraquinone synthon

Commercially available anthrarufin has been converted into a bifunctional reagent which will be useful for the preparation of anthraquinone C-glycosides.