Peptide-Based Optical/Electronic Materials: Assembly and Recent Applications in Biomedicine,Sensing, and Energy Storage

The unique optical and electronic properties of living systems are impressive. Peptide-based supramolecular self-assembly systems attempt to mimic these properties by preparation optical/electronic function materials with specific structure through simple building blocks, rational molecular design, and specific kinetic stimulation. From the perspective of building blocks and assembly strategies, the unique optical and electronic properties of peptide-based nanostructures, including peptides self-assembly and peptides regulate the assembly of external function subunits, are systematically reviewed. Additionally, their applications in biomedicine, sensing, and energy storage are also highlighted. This bioinspired peptide-based function material is one of the hot candidates for the new generation of green intellect materials, with many advantages such as biocompatibility, environmental friendliness, and adjustable morphology.     

Bioinspired catalyst design and artificial metalloenzymes

Many bioinspired transition-metal catalysts have been developed over the recent years. In this review the progress in the design and application of ligand systems based on peptides and DNA and the development of artificial metalloenzymes are reviewed with a particular emphasis on the combination of phosphane ligands with powerful molecular recognition and shape selectivity of biomolecules. The various approaches for the assembly of these catalytic systems will be highlighted, and the possibilities that the use of the building blocks of Nature provide for catalyst optimisation strategies are discussed.     

Photooxidase‐Mimicking Nanovesicles with Superior Photocatalytic Activity and Stability Based on Amphiphilic Amino Acid and Phthalocyanine Co‐Assembly

Enzyme mimics have broad applications in catalysis and can assist elucidation of the catalytic mechanism of natural enzymes. However, challenges arise from the design of catalytic sites, the selection of host molecules, and their integration into active three‐dimensional structures. Herein, we describe the development of a photooxidase mimic by synergetic molecular self‐assembly. 9‐Fluorenylmethyloxycarbonyl‐l ‐histidine undergoes efficient co‐assembly with phthalocyanine into nanovesicles with tunable particle size and membrane thickness. The obtained nanovesicles can be used as catalysts for reactive‐oxygen‐mediated photosensitive oxidation with improved efficiency and stability. This work highlights the co‐assembly of simple building blocks into a supramolecular photocatalyst, which might give insight into possible evolutionary paths of photocatalytic membrane systems, and might allow facile transfer into photosensitive nanoreactors or artificial organelles.     

Review: active homogeneous reagents and catalysts in n-alkane activation

The development of selective, efficient, and direct routes for activation and functionalization of naturally abundant n-alkanes could lead to a new paradigm in materials and energy technologies. In this context, the use of homogeneous catalysts to functionalize C–H bonds of unactivated hydrocarbons is of particular interest from a scientific as well as an economic viewpoint. Despite the large body of work on stoichiometric C–H activation reactions produced over the last three decades, relatively few systems have been developed to allow catalytic functionalization of hydrocarbons. This review deals with homogeneous catalytic processes available in the literature for paraffin activation and functionalization. The key intermediates involved in catalytic systems are highlighted, providing important information in the design of new and efficient catalysts. Also, some of the key challenges and approaches to rational development of the next generation of organometallic catalysts will be highlighted.     

Stereoselective Electrophilic Cyclization

Electrophilic cyclizations of unactivated alkenes play highly important roles in the synthesis of useful building blocks. This account describes our contributions to the rational design of monofunctionalized chiral Lewis base catalysts for enantioselective iodo‐ and protocyclizations. For the stereoselective promotion of electrophilic bromocyclizations, nucleophilic phosphite–urea cooperative catalysts have been designed.     

Transition‐Metal‐Free Coupling Reaction of Vinylcyclopropanes with Aldehydes Catalyzed by Tin Hydride

Donor–acceptor cyclopropanes are useful building blocks for catalytic cycloaddition reactions with a range of electrophiles to give various cyclic products. In contrast, relatively few methods are available for the synthesis of homoallylic alcohols through coupling of vinylcyclopropanes (VCPs) with aldehydes, even with transition‐metal catalysts. Here, we report that the hydrostannation of vinylcyclopropanes (VCPs) was effectively promoted by dibutyliodotin hydride (Bu₂SnIH). The resultant allylic tin compounds reacted easily with aldehydes. Furthermore, the use of Bu₂SnIH was effectively catalytic in the presence of hydrosilane as a hydride source, which established a coupling reaction of VCPs with aldehydes for the synthesis of homoallylic alcohols without the use of transition‐metal catalysts. In contrast to conventional catalytic reactions of VCPs, the presented method allowed the use of several VCPs in addition to conventional donor–acceptor cyclopropanes.     

Recent Advances of Precise Cu Nanoclusters in Microporous Materials

This minireview highlights some recent advances in the rational design of precise Cu nanoclusters supported on microporous materials, including zeolites and metal‐organic frameworks. The development of comprehensive characterisation techniques enables scientists to elucidate the structure‐activity relationship of these catalysts, which aids the subsequent engineering of more superior catalytic systems at an atomistic perspective.     

Scientific Grounds for the Application of Mechanochemistry to Catalyst Preparation

It is shown that mechanochemical activation is efficient in creating waste-free energy-saving methods for the preparation of hydride catalysts, heteropoly acid catalysts, and catalysts for hydrocarbon decomposition into hydrogen and carbon materials, as well for the syntheses of earlier unknown catalytic systems. The capabilities of the mechanochemical methods are demonstrated on modifying the catalytic properties of catalysts and supports: an increase in the strength and catalytic activity, sorption properties, etc. Adhesion theory applied to melts helps to describe the mechanism of mechanochemical synthesis of catalytic systems.     

Cover Picture

The cover picture shows a rhodium catalyst (green) that is encapsulated by three porphyrin molecules (black; the van der Waals radii are shown in yellow). The hemispherical assembly is obtained by a self‐assembly process using readily available pyridylphosphane and zinc‐porphyrin building blocks. Its exclusive formation is based on selective coordination of the nitrogen atom to the zinc atom and the phosphane group to the rhodium center. The catalyst assemblies show a higher activity than the free rhodium catalyst in the rhodium‐catalyzed hydroformylation of 1‐octene, and the branched product is now the main product. In a similar way, the assembly of porphyrin building blocks to pyridylphosphane can regulate the performance of palladium catalysts in the Heck reaction. Further details about these catalyst assemblies can be found in the article by Reek et al. on p. 4271ff.     

Remote Chiral Communication in Coadsorber‐Induced Enantioselective 2D Supramolecular Assembly at a Liquid/Solid Interface

Remote chiral communication in 2D supramolecular assembly at a liquid/solid interface was investigated at the molecular level. The stereochemical information in a chiral coadsorber was transmitted over a flexible spacer with a length of up to five methylene groups to a 2D supramolecular assembly of achiral building blocks with the cooperation of specific hydrogen bonding between the chiral coadsorber and achiral building blocks and the confinement effect during 2D crystallization. When the position of the stereogenic center was changed with respect to the stereocontrolling moiety, an odd–even effect was found. A stereogenic center closer to the stereocontrolling moiety transmitted the stereochemical information to the 2D supramolecular assembly more reliably. This result is beneficial not only for mechanistic understanding of chiral communication in 2D supramolecular assembly on surfaces but also for the rational design of homochiral supramolecular assemblies on surfaces.     

Reciprocal Self‐Assembly of Peptide–DNA Conjugates into a Programmable Sub‐10‐nm Supramolecular Deoxyribonucleoprotein

To overcome the limitations of molecular assemblies, the development of novel supramolecular building blocks and self‐assembly modes is essential to create more sophisticated, complex, and controllable aggregates. The self‐assembly of peptide–DNA conjugates (PDCs), in which two orthogonal self‐assembly modes, that is, β‐sheet formation and Watson–Crick base pairing, are covalently combined in one supramolecular system, is reported. Despite extensive research, most self‐assembly studies have focused on using only one type of building block, which restricts structural and functional diversity compared to multicomponent systems. Multicomponent systems, however, suffer from poor control of self‐assembly behaviors. Covalently conjugated PDC building blocks are shown to assemble into well‐defined and controllable nanostructures. This controllability likely results from the decrease in entropy associated with the restriction of the molecular degrees of freedom by the covalent constraints. Using this strategy, the possibility to thermodynamically program nano‐assemblies to exert gene regulation activity with low cytotoxicity is demonstrated.     

Pd/Al2O3催化剂的高温热烧结研究

以汽车尾气净化催化剂为背景，用溶胶－凝胶法和浸渍法制备了低负载量贵金属单钯燃烧催化剂。通过ＸＲＤ宽化法检测了在１２７３Ｋ的模拟反应气流中烧结２４ｈ后催化剂上Ｐｄ晶粒大小的变化。     

Combining in situ characterization methods in one set-up: looking with more eyes into the intricate chemistry of the synthesis and working of heterogeneous catalysts

Several in situ techniques are known which allow investigations of catalysts and catalytic reactions under real reaction conditions using different spectroscopic and X-ray methods. In recent years, specific set-ups have been established which combine two or more in situ methods in order to get a more detailed understanding of catalytic systems. This tutorial review will give a summary of currently available set-ups equipped with multiple techniques for in situ catalyst characterization, catalyst preparation, and reaction monitoring. Besides experimental and technical aspects of method coupling including X-ray techniques, spectroscopic methods (Raman, UV-vis, FTIR), and magnetic resonance spectroscopies (NMR, EPR), essential results will be presented to demonstrate the added value of multitechnique in situ approaches. A special section is focussed on selected examples of use which show new developments and application fields.     

碳载钴酞菁催化剂的制备及其氧还原催化性能研究

研究了一种通过固相加热一步合成碳载钴酞菁复合催化剂(CoPc/C)的制备方法.通过XRD,IR对制备的催化剂进行了表征.结果显示,得到的产物为CoPc/C,平均粒径30nm.利用极化曲线和交流阻抗等电化学方法测试了其在碱性介质中对氧还原的催化性能.该催化剂在碱性介质中(6mol·L-1KOH)空气气氛下,氧还原的初始电位达到0V,电极电位为-0.10V vs·Hg/HgO时电流密度达到100mA·cm-2,有显著的氧还原电催化效果.对实验得到的极化曲线及交流阻抗数据进行拟合处理及计算,获得相关动力学参数.     

Effect of preparation methods of aluminum emulsions on catalytic performance of copper-based catalysts for methanol synthesis from syngas

Various Cu/ZnO/Al2O3 catalysts have been synthesized by different aluminum emulsions as aluminum sources and their performances for methanol synthesis from syngas have been investigated. The influences of preparation methods of aluminum emulsions on physicochemical and catalytic properties of catalysts were studied by XRD, SEM, XPS, N2 adsorption--desorption techniques and methanol synthesis from syngas. The preparation methods of aluminum emulsions were found to influence the catalytic activity, CuO crystallite size, surface area and Cu⁰ surface area and reduction process. The results show that the catalyst CN using the aluminum source prepared by addition the ammonia into the aluminum nitrate (NP) exhibited the best catalytic performance for methanol synthesis from syngas.     

Combinatorial chemistry approach to chiral catalyst engineering and screening: rational design and serendipity

An efficient asymmetric catalyst relies on the successful combination of a large number of interrelated variables, including rational design, intuition, persistence, and good fortune-not all of which are necessarily well-understood; this renders such practice largely empirical. As a result, the possibility of using combinatorial chemistry methods in asymmetric catalysis research has been widely recognized to be highly desirable. In this account, we attempt to show the principle and application of combinatorial approach in the discovery of chiral catalysts for enantioselective reactions. The concept focuses on the strategy for the creation of a modular chiral catalyst library by two-component ligand modification of metal ions on the basis of molecular recognition and assembly. The self-assembled chiral catalyst with two different ligands indeed exhibited synergistic effects in terms of both enantioselectivity and activity in comparison with its corresponding homocombinations in many reactions. The examples described in this paper demonstrated the powerfulness of combinatorial approach for the discovery of novel chiral catalyst systems, particularly for the development of highly efficient, enantioselective, and practical catalysts for enantioselective reactions. We hope this concept will stimulate further work on the discovery of more highly efficient and enantioselective catalysts, as well as unexpected classes of catalysts or catalytic enantioselective reactions in the future with the help of a combinatorial chemistry approach.     

Quasi-continuous synthesis of cobalt single atom catalysts for transfer hydrogenation of quinoline

Improving the transfer hydrogenation of N-heteroarenes is of key importance for various industrial processes and remains a challenge so far. We reported here a microcapsule-pyrolysis strategy to quasicontinuous synthesis S, N co-doped carbon supported Co single atom catalysts(Co/SNC), which was used for transfer hydrogenation of quinoline with formic acid as the hydrogen donor. Given the unique geometric and electronic properties of the Co single atoms, the excellent catalytic activity, selectiv...     

Self-supported heterogeneous titanium catalysts for enantioselective carbonyl-ene and sulfoxidation reactions

A new strategy for the heterogenization of chiral titanium complexes was developed by the in situ assembly of bridged multitopic BINOL ligands with [Ti(OiPr)4] without using a support. The assembled heterogeneous catalysts (self-supported) showed excellent enantioselectivity in both the carbonyl-ene reaction of alpha-methylstyrene with ethyl glyoxylate (up to 98 % ee) and the oxidation of sulfides (up to >99 % ee). The catalytic performance of these heterogeneous catalytic systems was comparable or even superior to that attained with their homogeneous counterparts. The spacers between the two BINOL units of the ligands in the assembled catalysts had significant impact on the enantioselectivity of the carbonyl-ene reaction. This demonstrates the importance of the supramolecular structures of the assemblies on their catalytic behavior. In the catalysis of sulfoxidation, the self-supported heterogeneous titanium catalysts were highly stable and could be readily recycled and reused for over one month (at least eight cycles) without significant loss of activity and enantioselectivity (up to >99.9 % ee). The features of these self-supported catalysts, such as facile preparation, robust chiral structure of solid-state catalysts, high density of the catalytically active units in the solids, as well as easy recovery and simple recycling, are particularly important in developing methods for the synthesis of optically active compounds in industrial processes.