Polymers with Metal-Like Conductivity—A Review of their Synthesis,Structure and Properties

Polymers such as polyacetylene, which have an extended π-electron system in their backbone, or like poly(p-phenylene) consist of a sequence of aromatic rings are excellent insulators in their native state and can be transformed by oxidation or reduction in the solid state into conductive CT-complexes which exhibit metal-like conduction characteristics. The chemical and physical processes involved and the reasons for the observed quasimetallic conductivity are not yet fully understood. The real structure of these materials in chemical and physical terms, i. e. their complicated morphology and texture, as well as the results available on the structure-property relationships of the “organic metals” must be considered when discussing their properties. In other words, a discussion of conductive polymers should be based on what is known of the highly conducting CT-complexes of low-molecular weight compounds. The discovery of the highly conducting polymer complexes has opened up a new interdisciplinary field of research which borders on polymer science, solid-state and semiconductor physics and on organic solid-state chemistry. It is hoped that this area will lead to numerous novel materials and technical applications.     

Synthesis, structure, and photoluminescence of organosilicon based compounds containing stilbene, butadiene or styrene subunits

Seven silicon based model compounds that contain stilbene, butadiene or styrene subunits with different molecular structures were synthesized and characterized by NMR spectroscopy and single crystal X-ray crystallography. The UV-Vis absorption and photoluminescence spectra were measured in THF solution as well as in the solid state. The interpretation of the spectra reveals that the absorption and emission properties of the compounds originate from the stilbene or butadiene molecular subunits. This investigation provides basic information about the influence of silicon groups, molecular structures and substituents at silicon to absorption and emission properties in organic compounds. Furthermore, due to the functionality of the phenylethynyl substituents at silicon, these compounds may serve as optical active tools and precursors for the introduction of interesting physical properties into new materials for different applications.     

Host/Guest Chemistry of Organic Onium Compounds—Clathrates,Crystalline Complexes,and Molecular Inclusion Compounds in Aqueous Solution

The importance of organic onium compounds for host/guest interactions in biological processes has been long recognized. In contrast, the versatility of synthetic onium compounds as host molecules in abiotic chemistry has only been investigated in detail for the last few years. Due to their inclusion ability and selectivities, organic ammonium, pyridinium, and phosphonium salts and other organic salts with specific structural features are interesting as clathrate-forming molecules. The crystal structures of the clathrates afford insight into the conformational adaptability of onium clathrands with limited flexibility to the geometric requirements of the guest molecules. Optically active onium hosts can be used for enantiomeric enrichment. In crystalline tetracyanoquinodimethane(TCNQ) complexes and radical anion salts, the structure of the organic heterocation has a marked effect on the electrical conductivity. Macrocyclic onium compounds of the phane type with “exohydrophilic” and “endolipophilic” cavities are suitable as models of enzymes and biological receptors. They can also be used to transfer aromatic and aliphatic guest molecules selectively into aqueous solution. Catalytic activity (including H/D exchange) has already been obtained with synthetic compounds having large cavities. The further development of such host/guest systems may contribute to the understanding of biological systems and the improvement of technical processes (catalysis in molecular cavities).     

Nanoparticles,Proteins, and Nucleic Acids: Biotechnology Meets Materials Science

Based on fundamental chemistry, biotechnology and materials science have developed over the past three decades into today's powerful disciplines which allow the engineering of advanced technical devices and the industrial production of active substances for pharmaceutical and biomedical applications. This review is focused on current approaches emerging at the intersection of materials research, nanosciences, and molecular biotechnology. This novel and highly interdisciplinary field of chemistry is closely associated with both the physical and chemical properties of organic and inorganic nanoparticles, as well as to the various aspects of molecular cloning, recombinant DNA and protein technology, and immunology. Evolutionary optimized biomolecules such as nucleic acids, proteins, and supramolecular complexes of these components, are utilized in the production of nanostructured and mesoscopic architectures from organic and inorganic materials. The highly developed instruments and techniques of today's materials research are used for basic and applied studies of fundamental biological processes.     

二次有机气溶胶形成的化学过程

挥发性有机化合物的光氧化过程和光氧化产物的气态/粒子态均分过程是二次有机气溶胶形成的重要原因.二次有机气溶胶形成的化学机理主要涉及到挥发性有机化合物的光氧化过程及其一系列的后续反应,它们导致了对流层中臭氧浓度的增加和二次有机气溶胶的形成.本文将重点介绍二次有机气溶胶形成的重要化学过程和量子化学计算研究.     

苯并噻吩类稠环化合物的合成及其在有机场效应晶体管中研究的进展

总结了苯并噻吩类稠环化合物半导体材料的最新研究进展,对其合成方法及结构与性能进行了归纳,介绍了它们在有机场效应晶体管中的应用,并对其研究和应用前景进行了展望。     

Recent Advances in the Support Layer,Interlayer and Active Layer of TFC and TFN Organic Solvent Nanofiltration (OSN) Membranes: A Review

Although separation of solutes from organic solutions is considered a challenging process, it is inevitable in various chemical, petrochemical and pharmaceutical industries. OSN membranes are the heart of OSN technology that are widely utilized to separate various solutes and contaminants from organic solvents, which is now considered an emerging field. Hence, numerous studies have been attracted to this field to manufacture novel membranes with outstanding properties. Thin-film composite (TFC) and nanocomposite (TFN) membranes are two different classes of membranes that have been recently utilized for this purpose. TFC and TFN membranes are made up of similar layers, and the difference is the use of various nanoparticles in TFN membranes, which are classified into two types of porous and nonporous ones, for enhancing the permeate flux. This study aims to review recent advances in TFC and TFN membranes fabricated for organic solvent nanofiltration (OSN) applications. Here, we will first study the materials used to fabricate the support layer, not only the membranes which are not stable in organic solvents and require to be cross-linked, but also those which are inherently stable in harsh media and do not need any cross-linking step, and all of their advantages and disadvantages. Then, we will study the effects of fabricating different interlayers on the performance of the membranes, and the mechanisms of introducing an interlayer in the regulation of the PA structure. At the final step, we will study the type of monomers utilized for the fabrication of the active layer, the effect of surfactants in reducing the tension between the monomers and the membrane surface, and the type of nanoparticles used in the active layer of TFN membranes and their effects in enhancing the membrane separation performance.     

Dibenzoannelated tetrathienoacene: synthesis, characterization, and applications in organic field-effect transistors

Two structural isomers of six-fused-ring sulfur-containing molecules were synthesized as active materials for p-type organic field-effect transistors, and their optical and electrochemical properties were characterized. Field-effect transistors based on these compounds were fabricated to investigate the relationships between structures and semiconductor properties.     

Characterization of Carbon Based Nanoparticles Dispersion in Aqueous Solution Using Dynamic Light Scattering Technique

Characterization of physicochemical properties of nanoparticles in aqueous environment prior to conducting hazard studies is strongly recommended by many scientific organizations. In this work we studied the dissolution behaviour and physicochemical properties of carbon based nanoparticles in aqueous solution. The time evolution of the size distribution and the state of dispersion of carbon black and carbon nanotubes in physiological solution have been investigated by means of Dynamic Light Scattering technique. The influence of mechanical agitation such as sonication and stirring on the agglomeration state and particle size distribution has been investigated. However, such processes seem to have little or no effect as far as agglomeration is concerned.     

Organic nanoparticles from microemulsions: Formation and applications

Microemulsions have already been recognized as convenient templates for nanoparticle synthesis. Spontaneous formation of the compartmentalized domains within the microemulsions leads to facile and low-cost preparation processes.In the past, microemulsions were mainly explored as precursors for the synthesis of inorganic nanoparticles. However, there is a constantly growing number of publications offering to exploit these systems to produce organic nanoparticles, and in recent years, a variety of methods have emerged in this field. The aim of this review is to survey the methods recently used to produce organic nanomaterials from microemulsions, and to give a perspective on particle design possibilities that can be achieved by various techniques. The structure of the initial microemulsion system, the chemical and technical aspects of preparation, the nature of additives and surface active agents, as well as the possible outcomes in terms of final particle characteristics, will be discussed for the various methods.     

Molecular optical switches: synthesis, structure, and photoluminescence of spirosila compounds

Starting from a silicon dichloro substituted silole and a silacyclobutene, a series of new organosilicon-based spiro compounds was synthesized by using standard organometallic reaction procedures. The spiro compounds that combine two organic photoactive subunits at one silicon center were fully characterized by the usual analytical and spectroscopic methods, which include molecular structure determination by single-crystal X-ray analysis. Photoluminescence spectra of the compounds were recorded in the solid state and also as dilute solutions in THF. Interpretation of the spectra revealed that photoluminescence in this series of compounds originated from the stilbene or its vinylogue subunits. Different linkages of these groups to the silicon atoms (cyclic or open structures, four- or five-membered cycles) strongly affected both the excitation and the emission spectra, which show different emission maxima depending on the state of the sample (solid state or in solution) and the wavelength of light used for excitation. Thus, owing to their optoelectronic properties these compounds might be useful tools for the design of sensitive sensor materials and of optical switches.     

Progress in the development of cobalt-free drier systems

Driers are used in air-drying coating systems to catalyze the polymerization process. Cobalt-carboxylates are the most widely used driers. However, cobalt compounds may indirectly be implicated as carcinogen suspects as a result of studies in the U.S.A. in the national toxicology program using cobalt sulphate heptahydrate. Hence, Germany is no longer granting the Blue Angel award to cobalt-containing paints. Other transition metal carboxylates such as based on manganese or iron show much lower catalytic effects and cannot equalize cobalt as a catalyst in autoxidation polymerization reactions. The effect of various organic chelating ligands on the catalytic properties of manganese in autoxidation processes was investigated experimentally in air-drying paints. The activity of manganese is strongly effected by organic ligands. New manganese based coordination compounds enable the formulation of Co-free air-drying paints, which show good drying performances and improved color retention.     

Photochromism of organometallic compounds with structural rearrangement

This article introduces photochromic properties together with structures of organometallic compounds that undergo photo-induced structural rearrangement. The aim of this review is to survey the research on photochromism by using organometallics which possess by their own nature the properties responsible for the photochromism such as bonding and structural fluxionality, electronic state fluctuation, and photochemically active characteristic in both solution and the solid state. Therefore, the organometallics which include the well-characterized organic photochromic moieties, considered to be derivatives of such kinds of organic photochromic compounds, are excluded in this article. Mono-, di-, and poly-nuclear organometallic compounds are presented based on the reaction types such as linkage isomerization, haptotropic rearrangement, and reorganization of metal–ligand and/or metal–metal bonds. Very recently, the crystalline-state photochromism is becoming an attractive field of photochromic chemistry. As a demonstrative example, the photochromism of organometallic rhodium dinuclear complexes having a dithionite ligand (μ-O₂SSO₂), which shows 100% reversible interconversion in the crystalline-state and have been developed in the authors’ laboratory, will be discussed.     

Thermochemolysis of winery wastewater particulates—Molecular structural implications for water reuse

Environmental concerns have increased the interest in winery wastewater remediation and reuse. These practices require more detailed understanding of wastewater composition to ensure optimum usage, and to minimize the risk of long term soil degradation and grape contamination. Particulate organic matter is an important contributor to the carbon burden in winery wastewaters. This article investigates the molecular structure of particulates from the most common winery wastewater treatment processes via infrared spectroscopic and thermochemolysis-gas chromatography/mass spectrometry techniques. Study of the organic composition of both influent and effluent particles enabled further insight into which compounds could prove problematic during treatment and on discharge. The yield and molecular structure of desorbed or “guest” compounds were found to strongly correlate with those produced during pyrolytic cracking. These “guest” compounds and macromolecular fragments form a continuum whose separation is based on molecular size. Polyphenolic and lignin derived compounds tended to survive the water treatment processes within assemblages of microbial detritus. No evidence was found for particles adsorbing and concentrating other unrelated organics such as anthropogenic chemicals from winery wastewaters. Any release of particulates will require careful management to prevent localized accumulation of recalcitrant compounds to toxic levels.     

Analysis of chemical kinetics at the gas-aqueous interface for submicron aerosols

The effect of kinetics of chemical reactions in the gas-liquid interface between atmospheric gases and reactive solute in dilute aqueous aerosols is analysed in order to see if such processes will affect the overall uptake rate. Accordingly, a parameterization of such heterogeneous reactions was derived, taking into account interfacial reactions. Gibbs surface excess concentration of both reactive compounds and stable compounds leads to higher heterogeneous reaction rates in comparison to aqueous phase bulk reactions. An analytical formulation shows that the surface reactions may be of considerable importance for the uptake process in the case of small liquid aerosols even in the absence of organic film on the surface. In particular, we demonstrate that the uptake rate of atmospheric gas-phase oxidants (such as OH, NO(3) or O(3)) reacting with volatile organic compounds (such as ethanol or methanol) is increased by more than 10% for atmospheric aerosols with diameters lower than 0.1 microm. This effect is in addition intensified in the case of reactions of atmospheric oxidants with liquid aerosols containing organic surfactants, such as semi-volatile organic compounds, i.e., the chemical reactions at the gas-liquid interface may be dominant in the main uptake process for atmospheric submicron aerosols.     

Development of anisotropic ferromagnetic composites for low-frequency induction heating technology in medical applications

Modern medical applications such as varicose treatment, hyperthermia, or even endovenous thermal ablation require to bring heat flux locally through the human body. The challenge behind such techniques resides in converting electrical power into heat flux and transfer it directly to the targeted area without contaminating and damaging the surrounding tissues. Low-frequency induction heating (LFIH) of catheters made out of biocompatible magnetic composites is an elegant solution. By inserting the catheter through the varicose to be treated and by exciting it through LFIH, it seems possible to reach a temperature high enough to properly heal the damaged area while preserving the surrounding healthy ones. Although recent published results seem promising, an optimized procedure is still required to achieve further improvements. Many directions lying on the active material formulation have been largely explored in the past (variations of particle content, nature, size, and shape). In this work, we propose an alternative solution, which involves the processing of ferromagnetic composites under a constant homogeneous magnetic field, leading to the strong anisotropic behavior due to particles alignment. Remarkably, experimental results demonstrate that by exciting such anisotropic composites along the alignment direction enhances the LFIH effect by more than 30%. Moreover, improvements can also be noticed in the perpendicular direction, meaning that the structured distribution is enough to increase the ferromagnetic properties. Furthermore, the resulting composite is highly flexible, making it easier to be integrated in several medical devices (e.g. endovenous thermal catheter, electromagnetic tracking system, and so on).     

Membranes and membrane processes for chiral resolution

This critical review is devoted to an active field of research on chiral separation, membrane-based enantioseparation technique, which has potential for large-scale production of single-enantiomer compounds. Adsorption-type enantioselective membranes and membrane-assisted resolution systems with non-enantioselective solid membranes have attracted much attention recently. The principles and recent developments of both enantioselective liquid and solid membranes and membrane-assisted processes for chiral resolution will be summarized comprehensively in this review, in which the contents are of interest to a wide range of readers in a variety of fields from analytical, organic and medicinal chemistry, to pharmaceutics and materials, to process engineering for fabricating pharmaceuticals, agrochemicals, fragrances and foods, and so on (148 references).     

掺杂多孔碳材料催化醇选择性氧化研究进展

羰基化合物是重要的有机中间体,醇类化合物的选择性氧化是合成羰基化合物的一类重要反应.在这类反应中,掺杂多孔碳材料因其独特的性能可直接作为催化剂或者催化剂载体.我们综述了单一掺杂多孔碳材料、共掺杂多孔碳材料和负载型掺杂多孔碳材料的制备方法,可能存在的活性位点和催化机理.最后,讨论了掺杂多孔碳材料目前需要解决的问题,指出设计绿色高效的负载非贵金属的掺杂多孔碳材料是未来的一个重要发展方向.     

Solubility and Crystallizability: Facile Access to Functionalized π‐Conjugated Compounds with Chlorendylimide Protecting Groups

Functional π‐conjugated molecules are relevant for the preparation of new organic electronic materials with improved performance. However, their synthesis is often rendered difficult by their inherently low solubility, and the permanent attachment of solubilizing groups may change the properties of the material. Here, we introduced the chlorendylimidyl moiety as a new temporary protecting group for the straightforward large‐scale synthesis of protected quarter‐, sexi‐, octathiophene, and perylene bisimide diamine and dicarboxylic acid derivatives. The obtained chlorendylimides and chlorendylimidyl active esters were highly soluble in organic solvents, and optical spectroscopy confirmed the low tendency of the compounds to aggregate in solution. At the same time, they could be conveniently purified by recrystallization or precipitation. Single‐crystal X‐ray structures obtained for most compounds showed supramolecular motifs highlighting the role of the rigid, polychlorinated chlorendyl moieties in their crystallization. The obtained protected diamine and dicarboxylic acid derivatives were easily deprotected and converted into various amide‐substituted oligothiophenes and perylene bisimides that are of interest as new functional materials for organic electronic thin film or nanowire devices.