Polymeric Nanocomposites—Polyhedral Oligomeric Silsesquioxanes (POSS) as Hybrid Nanofiller

Abstract

Polyhedral oligomeric silsesquioxane (POSS), a hybrid nanostructured macromer has been used in the last decade for preparation of polymeric nanocomposites. Its versatile chemistry, which lends it for almost infinite chemical modification, sets it apart from other nanostructured fillers like nanoclays, carbon nanotubes, and carbon nanofibers. Depending on its functionality, 3‐D network, bead or pendant type‐POSS based polymeric nanocomposites can be synthesized. These have the potential to be designed for products with specific nanostructures for specific end‐use applications. This article discusses the trends in current research involving use of POSS macromers for modification of mainly thermal and viscoelastic properties of various polymers.     

Alternate Transition Metal Complex Based Diene Polymerization

Abstract

In the last decade, there has been a tremendous increase in the number of reports on transition metal complex-mediated butadiene homo- and copolymerization. While typical classical titanium, nickel, cobalt, and neodymium based catalysts have been almost exclusively applied to the production of high cis-1,4-polybutadiene, alternative catalyst systems are currently being developed which enable tuning of the polybutadiene microstructure and permit defined changes in polymer properties such as molecular weight distribution and changes in the polymer glass temperature. Besides new products such as high trans-1,4-polybutadiene or a polymer containing a defined amount of 1,2-polybutadiene, there are butadiene copolymers with different amounts of styrene, isoprene, or ethylene. These new materials should lead to new applications especially in the area of tires, high impact polystyrene (HIPS), and ABS. This review elucidates the new developments in the area of transition metal complex-based butadiene homo- and copolymerization focusing mainly on the transition metal catalyst, the polymerization process and the resulting polymers. Mechanistic details are discussed briefly and wherever useful for the understanding of the polymerization reaction.     

Magnetic nanomaterials catalyzed synthesis of tetrazoles

Abstract

Tetrazoles are valuable molecules in pharmaceutical and agriculture chemistry, because they are excited in many drugs, natural products and biologically active molecules. During the last decade, magnetic nanomaterials have appeared as highly efficient catalysts in chemical science in general organic chemistry, because of their simple preparation, modification, and large surface area ratio. In this paper, we provide an overview of the utilization of magnetic nanomaterials as attractive and efficient catalytic systems in synthesis of biologically active tetrazoles.     

Titanium dioxide nanomaterials in electrocatalysis for energy

Over the last two decades, researchers have found many strategies to obtain high surface area nanostructured titanium dioxide. These nanostructures have recently found application as supports for the fabrication of electrodes for electrochemical energy conversion and storage devices. The properties that make titanium dioxide appealing for these applications are as follows: (i) stability in a variety of conditions relevant to electrocatalysis, (ii) electronic conductivity, (iii) synergistic effects with metal catalysts. The work splits TiO₂ nanomaterials into the following two classes: (i) powders and (ii) embedded nanoarchitectures (e.g. titania nanotubes on titanium support). We give an overview of the latest applications, with a special emphasis on fuel cells, electrolysis, and carbon dioxide electroreduction. We conclude with a list of the research needs that, in the opinion of the authors, will support the exploration and consolidation of the use of titania in electrocatalysis for energy.     

Ferrite nanoparticles (MFe2O4 NPs) as magnetically recoverable supports for catalysis in organic synthesis

Abstract

Heterogenization of organic and metallic catalysts with a solid support is an attractive and useful strategy to solve the separation and recovery problems of catalysts. During the last decade, magnetic nanoparticles (MNPs) in general ferrite nanoparticles (MFe₂O₄ NPs) have emerged as a highly efficient support for catalysis, due to their simple fabrication, modification, and large surface area ratio. In this paper, we provide an overview of the utilization of organic and metallic molecules immobilized on magnetic ferrite nanoparticles (MFe₂O₄ NPs) as attractive and efficient catalytic systems in wide variety of in organic reactions.     

New Trends in Diaziridine Formation and Transformation (a Review)

This review focuses on diaziridine, a high strained three-membered heterocycle with two nitrogen atoms that plays an important role as one of the most important precursors of diazirine photoaffinity probes, as well as their formation and transformation. Recent research trends can be grouped into three categories, based on whether they have examined non-substituted, N-monosubstituted, or N,N-disubstituted diaziridines. The discussion expands on the conventional methods for recent applications, the current spread of studies, and the unconventional synthesis approaches arising over the last decade of publications.     

Amperometric biosensors based on electrosynthesised polymeric films

The most significant goals achieved in the course of the last decade in the design of amperometric biosensors based on redox enzymes entrapped in electrosynthesised polymeric films are reviewed. Particular emphasis is devoted to non-conducting polymers with built-in permselectivity that revealed very promising materials for designing fast-response and interference-free, H₂O₂ detecting, amperometric biosensors. The role of surface analytical techniques to provide structural information allowing a better understanding of polymers properties and their relationship with the ultimate performance of the final device is also outlined. The most relevant applications of amperometric biosensors based on electropolymerised films to real samples analysis are also reviewed and some possible future trends highlighted. Received: 12 November 1999 / Revised: 10 January 2000 / Accepted: 16 January 2000     

A Novel Type of Water-Soluble Chiral Phosphines Synthesis of Individual RR-and SS-Enantioisomers of Dipotassium 1,3-Di{Phenyl(Carboxylato)Methyl}-5-Phenyl-1,3,5-Diazaphosphorinane

Abstract

The last decade rapid development of catalytic reactions in organic solvent -water bifase systems, especially enantioselective processes, focused the attention of chemists on the synthetic roads to the chiral water-soluble phosphine ligands The reaction of bis(oxymethy1)phenyl-phosphine, paraform and (R)- or (S) α aminoacides open a road to a numerous chiral heterocyclic phosphines and their transition metal complexes with high water solubility.     

Graphene‐Assisted Room‐Temperature Synthesis of 2D Nanostructured Hybrid Electrode Materials: Dramatic Acceleration of the Formation Rate of 2D Metal Oxide Nanoplates Induced by Reduced Graphene Oxide Nanosheets

A new prompt room temperature synthetic route to 2D nanostructured metal oxide–graphene‐hybrid electrode materials can be developed by the application of colloidal reduced graphene oxide (RGO) nanosheets as an efficient reaction accelerator for the synthesis of δ‐MnO₂ 2D nanoplates. Whereas the synthesis of the 2D nanostructured δ‐MnO₂ at room temperature requires treating divalent manganese compounds with persulfate ions for at least 24 h, the addition of RGO nanosheet causes a dramatic shortening of synthesis time to 1 h, underscoring its effectiveness for the promotion of the formation of 2D nanostructured metal oxide. To the best of our knowledge, this is the first example of the accelerated synthesis of 2D nanostructured hybrid material induced by the RGO nanosheets. The observed acceleration of nanoplate formation upon the addition of RGO nanosheets is attributable to the enhancement of the oxidizing power of persulfate ions, the increase of the solubility of precursor MnCO₃, and the promoted crystal growth of δ‐MnO₂ 2D nanoplates. The resulting hybridization between RGO nanosheets and δ‐MnO₂ nanoplates is quite powerful not only in increasing the surface area of manganese oxide nanoplate but also in enhancing its electrochemical activity. Of prime importance is that the present δ‐MnO₂–RGO nanocomposites show much superior electrode performance over most of 2D nanostructured manganate systems including a similar porous assembly of RGO and layered MnO₂ nanosheets. This result underscores that the present RGO‐assisted solution‐based synthesis can provide a prompt and scalable method to produce nanostructured hybrid electrode materials.     

The First Synthesis of α-Methylene Isophosphindoline Oxide

Abstract

Over the last decade the intramolecular palladium-catalyzed coupling of haloarenes and haloalkenes with alkenes has proven to be a particularly valuable route to a wide variety of the structurally demanding cyclic and polycyclic systems We wish now to demonstrate its successhl application to the synthesis of the first parent representative of the five-membered ring carbon-phosphorus heterocycles possessing exocyclic unsaturation, a class of compounds remaining to date practically unexplored The effected synthesis of the a-methylene isophosphindoline oxide I is delineated in the equation which reveals also the optimized catalytic system and the prerequisite reaction conditions Of those, the reaction temperature is the most crucial parameter as the desired product undergoes unexpectedly facile thermal cyclodimerization to the spiropolycyclic system 2 frequently even precluding the isolation of 1.     

Ni‐Catalyzed Amination Reactions: An Overview

Nitrogen‐containing organic compounds are valuable in many fields of science and industry. The most reliable method for the construction of C(sp²)–N bonds is undoubtedly palladium‐catalyzed amination. In spite of the great achievements made in this area, the use of expensive Pd‐based catalysts constitutes an important limitation for large‐scale applications. Since nickel is the least expensive and most abundant among the group 10 metals, the interest in Ni‐based catalysts for processes typically catalyzed by palladium has grown considerably over the last few years. Herein, we revise the development of Ni‐catalyzed amination reactions, emphasizing the most relevant and recent advances in the field.     

ZnII Complexes for Bioimaging and Correlated Applications

Zinc is a biocompatible element that exists as the second most abundant transition metal ion and an indispensable trace element in the human body. Compared to traditional metal‐organic complexes systems, d¹⁰ metal Zn^II complexes not only exhibit a large Stokes shift and good photon stability but also possess strong emission and low cytotoxicity with a relatively small molecular weight. The use of Zn^II complexes has emerged in the last decade as a versatile and convenient tool for numerous biological applications, including bioimaging, molecular and protein recognition, as well as photodynamic therapy. Herein, we review recent developments involving Zn^II metal complexes applied as specific subcellular compartment imaging probes and their correlated utilizations.     

Broader,Greener, and More Efficient: Recent Advances in Asymmetric Transfer Hydrogenation

Asymmetric transfer hydrogenation has become a practically useful tool in reduction chemistry in the last decade or so. This was largely triggered by the seminal work of Noyori and co‐workers in the mid‐1990s and is driven by its complementing chemistry to hydrogenation employing H₂. This Focus Review attempts to present a “holistic” overview on the advances in the area, focusing on the achievements recorded around the last three years. These include more‐efficient and “greener” metal catalysts, catalysts that enable hydrogenation as well as transfer hydrogenation, biomimetic and organocatalysts, and their applications in the reduction of C?O, C?N, and C?C bonds. Also highlighted are efforts in the development of environmentally benign and reusable catalytic systems.     

Composite Particles: Design of Hybrid Materials on the Nano-Scale

Summary: In the last decade there has been a steady increased interest in the techniques providing design of nano-structured materials. It has been demonstrated that colloidal polymeric particles can be successfully used for the deposition of different functional nano-materials. Due to their numerous attractive properties polymeric particles have been used as templates for the synthesis, storage and transportation of nanostructured materials. This contribution demonstrates the synthetic ways for the preparation of hybrid particles by effective control over the size, morphology and distribution of the non-miscible phases. Developed methods allow design of the composite particles on the nanometer scale and opens new possibilities for the preparation of the materials with advanced properties. The synthesis, characterization and applications of hybrid particles are discussed in detail.     

Advances in Electrochemical and Catalytic Performance of Nanostructured FeCo2O4 and Its Composites

It is well established that the excessive and uncontrolled use of fossil fuels and organic chemicals have put a risk to the earth‘s environment and the life that sustains within it. Carbon-free, sustainable, alternative energy technologies have therefore become the prime focus of current research. Smart inorganic materials have emerged as the potential solution to suffice energy needs and remediate the organic pollutants discharged to the environment. One such promising, versatile material is FeCo₂O₄ which has gained immense research interest in the present decade due to its high efficiency and performance in energy and environmental applications. Innovative material design strategies involving the interplay of nanostructured morphology, chemical composition, redox surface states, and defect engineering have significantly enhanced both electrochemical and catalytic properties of FeCo₂O₄. Therefore, this review article aims to provide the first-ever comprehensive account of the latest research and developments in design-synthesis strategies, characterization techniques, and applications of nanostructured FeCo₂O₄ and its composites in various electrochemical as well as catalytic applications. A detailed account of the nanostructured FeCo₂O₄ and its composites in various energy storage and conversion devices such as supercapacitors (SCs), batteries, and fuel cells has been presented. Furthermore, a special section has been devoted to highlight the role of FeCo₂O₄ in enhancing the sluggish reaction kinetics of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in water splitting application. This review also highlights the role of nanostructured FeCo₂O₄ in photocatalytic waste water treatment, gas sensing, and dual-phase membrane technologies wherein FeCo₂O₄ has demonstrated promising performance.     

Temperature-sensitive aqueous microgels

An account of the preparation and characterization of temperature-sensitive aqueous microgels based on poly(N-isopropylacrylamide) was first published in 1986. Since then there has been a steady increase in the number of publications describing preparation, characterization and applications of temperature-sensitive microgels. This paper reviews the important developments in the area of temperature-sensitive aqueous microgels over the last decade. Although most of the work involves gels based on poly(N-isopropylacrylamide), other polymers are also considered. Core-shell latex particles exhibiting temperature-sensitive properties are also described.     

Chalcogen-containing metal chelates as single-source precursors of nanostructured materials: recent advances and future development

Abstract

The analysis of the use of chalcogenide metal chelates as single-source precursors of nanostructured materials has been carried out. The influence of the nature of the ligand, temperature, capping agents, thermolysis time, and solvent on the kinetic laws of thermolysis and the properties of the resulting nanomaterials is considered. Particular attention is paid to thermolysis of polynuclear chalcogenide metal chelates. The basic data on the synthesis of metal-polymer nanocomposites by thermolysis of chalcogenide metal chelates in the presence of polymers are summarized. The problems and future prospects of obtaining nanostructured materials by thermolysis of chalcogenide metal chelates are outlined. The bibliography includes articles published during the last 5 years.     

Quantifying protein adsorption and function at nanostructured materials: enzymatic activity of glucose oxidase at GLAD structured electrodes

Nanostructured materials strongly modulate the behavior of adsorbed proteins; however, the characterization of such interactions is challenging. Here we present a novel method combining protein adsorption studies at nanostructured quartz crystal microbalance sensor surfaces (QCM-D) with optical (surface plasmon resonance SPR) and electrochemical methods (cyclic voltammetry CV) allowing quantification of both bound protein amount and activity. The redox enzyme glucose oxidase is studied as a model system to explore alterations in protein functional behavior caused by adsorption onto flat and nanostructured surfaces. This enzyme and such materials interactions are relevant for biosensor applications. Novel nanostructured gold electrode surfaces with controlled curvature were fabricated using colloidal lithography and glancing angle deposition (GLAD). The adsorption of enzyme to nanostructured interfaces was found to be significantly larger compared to flat interfaces even after normalization for the increased surface area, and no substantial desorption was observed within 24 h. A decreased enzymatic activity was observed over the same period of time, which indicates a slow conformational change of the adsorbed enzyme induced by the materials interface. Additionally, we make use of inherent localized surface plasmon resonances in these nanostructured materials to directly quantify the protein binding. We hereby demonstrate a QCM-D-based methodology to quantify protein binding at complex nanostructured materials. Our approach allows label free quantification of protein binding at nanostructured interfaces.