Redox-responsive carbometalated ruthenium and osmium complexes

Organometallic conjugated complexes have become an important type of stimuli-responsive materials because of their appealing electrochemical properties and rich photonic, electronic, and magnetic properties. They are potentially useful in a wide range of applications such as molecular wires, molecular switches, molecular machines, molecular memory, and optoelectronic detections. This review outlines the recent progress on the molecular design of carbometalated ruthenium and osmium complexes and their applications as redox-responsive materials with visible and near-infrared (NIR) absorptions and electron paramagnetic resonance as readout signals. Three molecule systems are introduced, including the symmetric diruthenium complexes, metal-amine conjugated bi-center system, and multi-center redox-active organometallic compounds. Because of the presence of a metal-carbon bond on each metal component and strong electronic coupling between redox sites, these compounds display multiple reversible redox processes at low potentials and each redox state possesses significantly different physical and chemical properties. Using electrochemical potentials as input signals, these materials show reversible NIR absorption spectral changes, making them potentially useful in NIR electrochromism and information storage.     

Organometallic acetylides of Pt(II), Au(I) and Hg(II) as new generation optical power limiting materials

Within the scope of nonlinear optics, optical power limiting (OPL) materials are commonly regarded as an important class of compounds which can protect the delicate optical sensors or human eyes from sudden exposure to damaging intense laser beams. Recent efforts have been devoted to developing organometallic acetylide complexes, dendrimers and polymers as high performance OPL materials of the next generation which can favorably optimize the optical limiting/transparency trade-off issue. These metallated materials offer a new avenue towards a new family of highly transparent homo- and heterometallic optical limiters with good solution processability which outperform those of current state-of-the-art visible-light-absorbing competitors such as fullerenes, metalloporphyrins and metallophthalocyanines. This critical review aims to provide a detailed account on the recent advances of these novel OPL chromophores. Their OPL activity was shown to depend strongly on the electronic characters of the aryleneethynylene ligand and transition metal moieties as well as the conjugation chain length of the compounds. Strategies including copolymerization with other transition metals, change of structural geometry, use of a dendritic platform and variation of the type and content of transition metal ions would strongly govern their photophysical behavior and improve the resulting OPL responses. Special emphasis is placed on the structure-OPL response relationships of these organometallic acetylide materials. The research endeavors for realizing practical OPL devices based on these materials have also been presented. This article concludes with perspectives on the current status of the field, as well as opportunities that lie just beyond its frontier (106 references).     

Organometallic Polymers of the Transition Metals

This article provides a comprehensive review of the synthesis, properties and applications of organometallic polymers of the transition metals. The different classes of organometallic polymers are described according to their structural make‐up, as well as by their methods of synthesis. A number of examples of each class are given to emphasize the richness and diversity in these areas of research. In addition to linear polymers, hyperbranched, crosslinked, star and dendritic polymers are also described. The properties that transition metal‐containing organometallic polymers possess, as well as the applications that these materials have found in various domains are highlighted.

     

Recent advances in synthesis and applications of transition metal containing mesoporous molecular sieves

Work in mesoporous silica-based materials began in the early 1990s with work by Mobil. These materials had pore sizes from 20-500 A and surface areas of up to 1500 m(2) g(-1) and were synthesized by a novel liquid crystal templating approach. Researchers subsequently extended this strategy to the synthesis of mesoporous transition metal oxides, a class of materials useful in catalysis, electronic, and magnetic applications because of variable oxidation states, and populated d-bands-features not found in silicates. These materials are already showing promise in electronic and optical applications hinging on the semiconducting properties of transition metal oxides and their potential to act as electron acceptors, an important feature in the design of cathodic materials. This is the first general review of non-silicate mesoporous materials and will focus on recent advances in this area, emphasizing materials possessing unique electronic, magnetic, or optical properties. Also covered are advances in the synthesis and applications of mesostructured sulfides as well as a new class of template-synthesized platinum-based materials that show promise in heterogeneous catalysis.     

Optimizing the self-assembly of conjugated polymers and small molecules through structurally programmed non-covalent control

Organic conjugated polymers and oligomers are key electronic materials for applications such as transistors, photovoltaics, and light emitting devices due to their potential for solution processability, mechanical flexibility, and precise structure-based tuning compared to inorganic materials. In dilute environments, the optoelectronic properties of conjugated polymers are largely governed by their constitutional structure and, to a lesser degree, their solution-state intramolecular configuration. In the solid state, intramolecular conformation and intermolecular electronic coupling impact these properties substantially, especially in relation to device performance. Therefore, an increasingly important area of research concerning conjugated materials is developing design strategies aimed at optimizing the solid-state packing for electronic applications. Programming solid-state packing arrangements through discrete non-covalent interactions is an emerging strategy within the context of conjugated polymers. This review focuses on the use of the two most prevalent discrete and directional interactions used to dictate the self-assembly of conjugated polymers and oligomers—hydrogen bonds and chalcogen bonds. We also discuss how these design motifs can imbue conjugated materials with appealing physical properties while simultaneously retaining or improving electronic capabilities.     

Highly stable olefin-Cu(I) coordination oligomers and polymers

Highly stable Cu(I)-olefin coordination oligomers and polymers have been successfully prepared and applied to construct metal-organic frameworks (MOFs) with interesting physical and chemical functions in recent years. In this review, we present the olefin-Cu(I) coordination oligomers and polymers and their novel physical properties. From structure to functions, particular emphasis is placed on the coordination and organometallic chemistry of olefin-Cu(I) coordination oligomers and polymers, their structures and potential applications as solids possessing unusual physical functional properties such as electrochemical, chiral separation, fluorescent sensing and ferroelectricity.     

Controlling polymer properties through dynamic metal-ligand interactions: supramolecular cruciforms made easy

A straightforward methodology towards the supramolecular synthesis of novel organometallic polymers with attractive optical properties is presented. By coordinating bifunctional fluorescent cruciform molecules through ditopic metalated pincer complexes (Pd or Pt), we have synthesized a new class of well-defined coordination polymers that have controllable and tunable physical and photophysical properties. The formation of these new materials by employing metal coordination was monitored by (1)H NMR spectroscopy, the association strength of the metal-ligand interaction was measured by isothermal titration calorimetry, the solution polymeric properties were evaluated by viscometry, and the optical properties were measured and observed by fluorescence spectroscopy. The fast and quantitative synthesis of a wide range of prefabricated monomeric cruciform and metalated-pincer-complex components will allow for the rapid generation, growth, and optimization of this new class of functional polymers, which have potential electronic and optical applications.     

基于磷光材料的电致发光二极管研究进展

电致发光二极管(LEDs)具有能耗低、寿命长、绿色环保等优点,在固态照明、全色显示等领域具有广阔的应用前景。 与传统的荧光电致LEDs相比,磷光电致LEDs能够同时利用单重态和三重态激子,理论上可以使器件的内量子效率达到100%,突破5%的外量子效率极限。 因此,发展高效的磷光材料以及实现其在电致LEDs中的应用是非常有意义的。 本文综述了目前主要的磷光材料,包括有机金属配合物、纯有机分子、聚合物、金属有机框架材料和碳量子点等,并总结了稀有金属配合物和纯有机分子在电致磷光 LEDs中的研究进展,同时对电致磷光LEDs的发展前景进行展望。     

Luminescent organometallic poly(aryleneethynylene)s: functional properties towards implications in molecular optoelectronics

This article highlights recent progress in the development of rigid-rod metallopolyyne polymers of late transition metals which can exhibit easily tunable luminescent and electronic properties. Considerable focus is placed on the design strategies towards the tuning capability of phosphorescence emission color and optical bandgap of this class of luminescent metallopolymers, and the evaluation of their suitability as emitters in light-emitting applications, optical power limiters for sensor protection and semiconductors in organometallic photovoltaic cells. An effective approach based on structural modification of the spacer group can be devised to achieve the full-color phosphorescence emission spanning almost the whole visible spectrum and to tune the material properties of these functional organometallic polymers. The major advances, ongoing challenges and future perspectives of this research frontier are also discussed.     

富勒烯(C~6~0, C~7~0)的金属有机化学

综述了1990年以来富勒烯金属有机化学研究的进展,结果表明富勒烯(C~6~0,C~7~0)能与第VIII及IVB、VB、VIB、VIIB族等过渡金属形成各类衍生物,具有潜在的应用前景。     

Anhydrous scandium, yttrium, lanthanide and actinide halide complexes with neutral oxygen and nitrogen donor ligands

Studies on lanthanide and actinide halide complexes with neutral O- and/or N-donor ligands have intensified in recent years due to their implications in homogeneous catalysis, magnetic and optical materials, as synthons for the synthesis of novel coordination and organometallic compounds and, for Ln(II) halide complexes, as reducing agents in organic synthesis. Synthetic strategies, structural diversity as well as some important properties and reactivities of these anhydrous metal (including scandium and yttrium) halide complexes are reviewed here. These complexes also hold potential as starting materials for constructing more sophisticated heterometallic assemblies by crystal engineering; the compounds of this class, either discrete ion-pairs or coordination polymers, being discussed separately under the heading heterometallic lanthanide and actinide halide complexes. The aim of this article is to provide a reference text for the researchers working in the lanthanide and actinide coordination chemistry field and to identify and signify the area of future research.     

Hofmeister effects of anions on self-assembled thermogels

Thermogels are temperature-responsive soft biomaterials with numerous biomedical applications. They possess high water content and can spontaneously gelate by forming non-covalent physical crosslinks between their constituent amphiphilic polymers when warmed. However, despite the ubiquity of salts in biological fluids and buffer media, the influence of salts on thermogelling polymers and the overall physical properties of the resulting hydrogels are poorly understood. Herein, we elucidate the effects of common inorganic salts on the gelation and micellization properties of a thermogelling polymer containing poly(ethylene glycol), poly(propylene glycol), and poly(caprolactone) components. The identity of the salts' anions and their concentrations was found to exhibit significant effects on the thermogel properties, in some cases being able to decrease the sol-to-gel phase transition by up to 10 °C. We demonstrate that these notable influences are likely brought about by the changes in solvation of both the polymer's hydrophobic and hydrophilic segments, as well as by direct interactions of poorly hydrated anions with the hydrophobic polymer segments. Our findings show that the effects of salts on amphiphilic thermogelling polymers are non-negligible and hence need to be taken into account for engineering and optimization of thermogel properties for different biomedical applications.     

固体表面金属有机化合物的结构及其性质

表面金属有机化学是近年来一个快速发展的新研究领域。通过这种思想和方法所合成出的表面金属有机化合物具有明确的结构和特殊的性质,在催化研究和材料制备中有着广泛的应用,国内外已经进行了大量的研究并取得了许多非常有价值的结果。本文引用了40余篇文献侧重评述了氧化物、金属、沸石等固体表面金属有机化合物的结构和性质。     

Classification and synthesis of nickel pincer complexes

Over the past decades, the pincer ligands have attracted an increasing interest due to the unique properties of the coordination compounds they form. These monoanionic tridentate ligands are of great importance in organometallic and coordination chemistry. Their complexes with transition metals are used as homogeneous catalysts for various processes and also as functional materials with specified properties. The metal complexes formed by the pincer ligands provide an efficient alternative to the existing catalysts based on noble metals and, hence, the use of these complexes is a promising task of the modern chemical science. Therefore, nickel as the most accessible and inexpensive analog of palladium and platinum is of great practical interest. In this review, we consider the diversity of nickel complexes with pincer ligands, as well as the existing methods for their preparation and practical application.     

Cover Picture: Angew. Chem. Int. Ed. 16/2002

The cover picture shows the molecular modeling of a star‐shaped metallo‐supramolecular polymer and the schematic drawing of a linear analogue. These molecules are of great interest because of their unique properties. Metallo‐supramolecular polymers emerge by the well‐directed combination of polymers, the properties of which have dominated the development of materials in recent years, with supramolecular ligands, which have the ability to organize spontaneously and form unique structures on a molecular level, and transition‐metal ions, which, through their physical properties bring characteristic functionalities. The well‐known properties of the individual components allow the use of established methods, such as UV/Vis spectroscopy, NMR spectroscopy, and gel permeation chromatography for characterization. However, the combination also requires the application of new methods, such as analytical ultracentrifugation or MALDI‐TOF mass spectrometry. More about metallo‐supramolecular polymers based on bipyridine and terpyridine complexes can be found in the review by U. S. Schubert and C. Eschbaumer on p. 2892 ff.     

New applications of poly(arylene ether)s in organic light-emitting diodes

Compared with conventional π-conjugated polymers,poly(arylene ether)s(PAEs) may take advantages of excellent thermal properties,well-defined effective conjugated length and no catalyst contamination.Recently,their applications have been extended from engineering plastics to optoelectronic materials.In this review,various kinds of functional PAEs used as fluorescent polymers,host polymers and phosphorescent polymers in organic light-emitting diodes(OLEDs) are outlined,and their molecular design,synthesis and device performance are overviewed.     

Thin metal nanostructures: synthesis,properties and applications

Two-dimensional nanomaterials, especially graphene and single- or few-layer transition metal dichalcogenide nanosheets, have attracted great research interest in recent years due to their distinctive physical, chemical and electronic properties as well as their great potentials for a broad range of applications. Recently, great efforts have also been devoted to the controlled synthesis of thin nanostructures of metals, one of the most studied traditional materials, for various applications. In this minireview, we review the recent progress in the synthesis and applications of thin metal nanostructures with a focus on metal nanoplates and nanosheets. First of all, various methods for the synthesis of metal nanoplates and nanosheets are summarized. After a brief introduction of their properties, some applications of metal nanoplates and nanosheets, such as catalysis, surface enhanced Raman scattering (SERS), sensing and near-infrared photothermal therapy are described.     

Applications of luminescent inorganic and organometallic transition metal complexes as biomolecular and cellular probes

The rich photophysical properties of luminescent inorganic and organometallic transition metal complexes, such as their intense, long-lived, and environment-sensitive emission, render them excellent candidates for biological and cellular studies. In this Perspective, we review examples of biological probes derived from luminescent transition metal complexes with a d(6), d(8), or d(10) metal center. The design of luminescent covalent labels and noncovalent probes for protein molecules is discussed. Additionally, the recent applications of these complexes as cellular probes and bioimaging reagents are described. Emphasis is put on the structural features, photophysical behavior, biomolecular interactions, cellular uptake, and intracellular localization properties of luminescent transition metal complexes.     

Synthesizing optoelectronic heteroaromatic conjugated polymers by cross-coupling reactions

Heteroaromatics-containing polymers comprise a huge class of materials that have received considerable attention due to their interesting electrical, electrochemical, and optical properties. In this review, the recent advances on the use of organometallic cross-coupling reactions for the synthesis of heteroaromatic conjugated polymers for the optoelectronic interests and applications are summarised.     

Chemical approach to neutral–ionic valence instability,quantum phase transition,and relaxor ferroelectricity in organic charge-transfer complexes

Neutral–ionic (NI) phase transition is a reversible switching of organic charge-transfer complexes between distinct valence states by external stimuli. This phase transformation in the low-dimensional system is demonstrated to provide a variety of novel dielectric, structural, and electronic properties. Importantly, ionization of the electron donor–acceptor pairs is usually accompanied by a ferroelectric or antiferroelectric order of the molecular lattice, leading to huge dielectric response near the transition point. Although these characteristics are potentially useful for future electronic and optical applications, the thermally accessible NI transition (TINIT) is still an extremely rare case. The TINIT compounds including some new materials are overviewed in order to provide convenient guides to their design and experimental identifications. The phase transition and dielectric properties can be closely controlled in various ways depending on chemical and physical modifications of the crystals. Among them, a quantum phase transition and relaxor ferroelectricity, both of which are currently attracting subjects from both scientific and practical perspectives, are highlighted as the first achievements in organic charge-transfer complexes.