3-Aminopropylsilatrane and Its Derivatives: A Variety of Applications

Silatranes arouse much research interest owing to their unique structure, unusual physical–chemical properties, and diverse biological activity. The application of some silatranes and their analogues has been discussed in several works. Meanwhile, a comprehensive review of the wide practical usage of silatranes is still absent in the literature. The ability of silatranes to mildly control hydrolysis allows them to form extremely stable and smooth siloxane monolayers almost on any surface. The high physiological activity of silatranes makes them prospective drug candidates. In the present review, based on the results of numerous previous studies, using the commercially available 3-aminopropylsilatrane and its hybrid derivatives, we have demonstrated the high potential of 1-organylsilatranes in various fields, including chemistry, biology, pharmaceuticals, medicine, agriculture, and industry. For example, these compounds can be employed as plant growth biostimulants, drugs, optical, catalytic, sorption, and special polymeric materials, as well as modern high-tech devices.     

An overview of the chemistry of homo and heteropolynuclear platinum complexes containing bridging acetylide (μ-C≡CR) ligands

Different aspects of transition metal alkynyl chemistry have been widely studied over the past decades because of their interesting structures, chemical reactivity and properties. This review describes the chemistry of homo and heteropolynuclear platinum complexes containing bridging ligands, with special emphasis in synthetic routes, structural aspects and photoluminescence properties.     

Recent developments in the supramolecular chemistry of terpyridine-metal complexes

This critical review describes recent developments in the field of supramolecular chemistry of terpyridine-metal complexes. The synthesis and characteristics of single as well as multiple homo- and heterometallic complexes is discussed. Furthermore, complexes containing fullerenes, biological building blocks, extended aggregates of different architectures as well as rings are presented. A special emphasis is placed upon the properties (e.g. redox properties, luminescence etc.) of functional systems. Potential applications in optical nano-devices, molecular storage units, molecular switches and solar cells are discussed.     

Squaramides: physical properties, synthesis and applications

Squaramides are remarkable four-membered ring systems derived from squaric acid that are able to form up to four hydrogen bonds. A high affinity for hydrogen bonding is driven through a concomitant increase in aromaticity of the ring. This hydrogen bonding and aromatic switching, in combination with structural rigidity, have been exploited in many of the applications of squaramides. Substituted squaramides can be accessed via modular synthesis under relatively mild or aqueous conditions, making them ideal units for bioconjugation and supramolecular chemistry. In this tutorial review the fundamental electronic and structural properties of squaramides are explored to rationalise the geometry, conformation, reactivity and biological activity.     

Supported gold nanoparticles as catalysts for organic reactions

This critical review is intended to attract the interest of organic chemists and researchers on green and sustainable chemistry on the catalytic activity of supported gold nanoparticles in organic transformations. In the general part of this critical review, emphasis is given to the different procedures to form supported gold nanoparticles and to the importance of the support cooperating in the catalysis. Also the convergence of homogeneous and heterogeneous catalysis in the study of gold nanoparticles has been discussed. The core part of this review is constituted by sections in which the reactions catalyzed by supported gold nanoparticles are described. Special emphasis is made on the unique ability of gold catalysts to promote additions to multiple C-C bonds, benzannulations and alcohol oxidation by oxygen (282 references).     

Metal 2-ethylhexanoates and related compounds as useful precursors in materials science

This critical review deals with the chemistry and applications of metal alkanoates with medium size (C5 to C12) carbon chain length. A particular emphasis is given to metal 2-ethylhexanoates, which find wide applications as metal-organic precursors in materials science, as catalysts for ring opening polymerizations and also in painting industries for their properties as driers. After a brief introduction and an overview of synthesis, structural and physico-chemical properties, this article discuses extensively the applications of these compounds in materials science. Finally, it identifies and signifies the areas for future research in the looking ahead section. The aim of this review is to bridge the areas of precursor's chemistry and materials science by providing a reference text for researchers working either in or at the interface of these two areas (125 references).     

含碳硼烷金属有机化学研究进展

碳硼烷因其独特的性质,及其在应用方面的广阔前景,受到化学家们的广泛关注。本文将从结构、合成、机理、催化,以及生物活性等方面概述含碳硼烷的金属有机化学的部分最新进展。着重论述了与16e金属碳硼烷相关的反应、机理及产物。     

Crystal structure of 1-[N-2-aminoethyl)-aminopropyl]silatrane

The crystal structure of 1-[N-(2-aminoethyl)aminopropyl]silatrane has been determined by x-ray diffraction at room temperature. The Si←N bond distance (2.165(2) Å) is in the range observed for other 1-X-propylsilatranes (X = CN, OH, SH, Cl and SCN). The structure is partially disordered: the silatrane moiety displays a disorder that is typical for silatranes and the aminoethyl group terminating the planar chain linked to silicon is rotationally disordered.     

Synthesis and properties of colloidal heteronanocrystals

Colloidal heteronanocrystals (HNCs) can be regarded as solution-grown inorganic-organic hybrid nanomaterials, since they consist of inorganic nanoparticles that are coated with a layer of organic ligand molecules. The hybrid nature of these nanostructures provides great flexibility in engineering their physical and chemical properties. The inorganic particles are heterostructured, i.e. they comprise two (or more) different materials joined together, what gives them remarkable and unique properties that can be controlled by the composition, size and shape of each component of the HNC. The interaction between the inorganic component and the organic ligand molecules allows the size and shape of the HNCs to be controlled and gives rise to novel properties. Moreover, the organic surfactant layer opens up the possibility of surface chemistry manipulation, making it possible to tailor a number of properties. These features have turned colloidal HNCs into promising materials for a number of applications, spurring a growing interest on the investigation of their preparation and properties. This critical review provides an overview of recent developments in this rapidly expanding field, with emphasis on semiconductor HNCs (e.g., quantum dots and quantum rods). In addition to defining the state of the art and highlighting the key issues in the field, this review addresses the fundamental physical and chemical principles needed to understand the properties and preparation of colloidal HNCs (283 references).     

New development of synthesis and reactivity of seleno- and tellurophenes

Due to the many new and remarkable findings and applications that have been published in recent years in seleno- and tellurophene chemistry, this review revisits the different aspects of this chemistry, including synthesis, reactivity and applications in the field of heterocycles.     

Five-membered ring systems with one heteroatom: Synthetic routes,chemical reactivity,and biological properties of furan-carboxamide analogues

This review described the synthetic methods, chemical reactivity and biological applications of furan carboxamide compounds. Furan-carboxamides are reported to have important and variable biological properties. The aim of this review is to highlight the chemistry and biological importance of this class of bioactive compounds. The basic sections covers: structure studies, synthetic methods pathways, synthesis of different heterocycles, reactions and biological applications. The reactions mechanisms of the unexpected products are discussed. The present study covers all the published work on the furan-carboxamides until now.     

Continuous chirality measures in transition metal chemistry

The definition of the continuous chirality measure(CCM) is provided and its applications are summarized in this tutorial review, with special emphasis on the field of transition metal complexes. The CCM approach, developed in recent years, provides a quantitative parameter that evaluates the degree of chirality of a given molecule. Many quantitative structural correlations with chirality have been identified for most of the important families of metal complexes. Our recent research has shown that one can associate the chirality measures with, e.g., enantioselectivity in asymmetric catalysis. We also explore a fragment approach to chirality in which we investigate which part of a molecule is responsible for the chirality-associated properties of a given family of compounds.     

Structural aspects of a possible transannular interaction in silatranes and azasilatranes: An ab initio study

Complete geometry optimizations using ab initio SCF/3-21G* calculations were performed on silatrane and azasilatrane, on their fluoro derivatives, and on methylsilatrane. By comparison with optimized geometries obtained for a series of model systems, the predicted transannular internuclear distances were interpreted in terms of the combined effects of electronegative substituents on Si and the anomeric interaction in the silatranes. The predicted geometries indicate that there is a weak transannular interaction in silatrane and a more significant one in azasilatrane, the predicted equilibrium distances being 2.66 and 2.15 Å, respectively. © 1996 John Wiley & Sons, Inc.     

Electroanalysis based on stand-alone matrices and electrode-modifying films with silica sol-gel frameworks: a review

Silica sol-gel matrices and its organically modified analogues that contain aqueous electrolytes, ionic liquids, or other ionic conductors constitute stand-alone solid-state electrochemical cells when hosting electrodes or serve as modifying films on working electrodes in conventional cells. These materials facilitate a wide variety of analytical applications and are employed in various designs of power sources. In this review, analytical applications are the focus. Solid-state cells that serve as gas sensors, including in chromatographic detectors of gas-phase analytes, are described. Sol-gel films that modify working electrodes to perform functions such as hosting electrochemical catalysts and acting as size-exclusion moieties that protect the electrode from passivation by adsorption of macromolecules are discussed with emphasis on pore size, structure, and orientation. Silica sol-gel chemistry has been studied extensively; thus, factors that control its general properties as frameworks for solid-state cells and for thin films on the working electrode are well characterized. Here, recent advances such as the use of dendrimers and of nanoscale beads in conjunction with electrochemically assisted deposition of silica to template pore size and distribution are emphasized. Related topics include replacing aqueous solutions as the internal electrolyte with room-temperature ionic liquids, using the sol-gel as an anchor for functional groups and modifying electrodes with silica-based composites.

     

The organic chemistry of silver acetylides

Silver acetylides are among the oldest organometallics known; however, their applications in organic chemistry remained scarce until very recently. Indeed, several reactions involving silver salts as catalyst or silver acetylides have been reported in the past five years. The extreme mildness and very low basicity of these nucleophilic reagents nicely complement the behavior of other alkynyl metals, rendering them very useful in various transformations, especially in the synthesis of complex molecules. Silver acetylides are now seen as promising tools in organic chemistry. This critical review focuses on this emerging field, and, with emphasis on mechanistic aspects, cover the synthesis of silver acetylides, their applications in organic chemistry and reactions involving silver salts as catalysts where silver acetylides are probable intermediates.     

The influence of intermolecular interactions on the SiH bond vibration in silatrane and its c-substituents

Spectra of the silatrane HSi(OCHRCH₂)₃N and its 3,7,10-trimethyl- and -trifluoromethyl derivatives have been studied. The dependences of frequency and integral intensity of the SiH vibration on solvent polarity and temperature have been established. It has been shown that interaction of silatrane molecules with the solvent is universal in character. The phenomenon of the changing SiH vibration is explained by the possible formation of a three-centered orbital bending the atoms of hydrogen, silicon and nitrogen. In contrast to triethoxysilane, a dependence between v(SiH) and Σσ1 values of substituents in the cycle has been observed for silatranes.     

Advanced Developments in Cyclic Polymers: Synthesis,Applications, and Perspectives

Due to the topological effect, cyclic polymers demonstrate different and unique physical and biological properties in comparison with linear counterparts having the same molecular-weight range. With advanced synthetic and analytic technologies, cyclic polymers with different topologies, e.g. multicyclic polymers, have been reported and well characterized. For example, various cyclic DNA and related structures, such as cyclic duplexes, have been prepared conveniently by click chemistry. These types of DNA have increased resistance to enzymatic degradation and have high thermodynamic stability, and thus, have potential therapeutic applications. In addition, cyclic polymers have also been used to prepare organic–inorganic hybrids for applications in catalysis, e.g. catalyst supports. Due to developments in synthetic technology, highly pure cyclic polymers could now be produced in large scale. Therefore, we anticipate discovering more applications in the near future. Despite their promise, cyclic polymers are still less explored than linear polymers like polyolefins and polycarbonates, which are widely used in daily life. Some critical issues, including controlling the molecular weight and finding suitable applications, remain big challenges in the cyclic-polymer field. This review briefly summarizes the commonly used synthetic methodologies and focuses more on the attractive functional materials and their biological properties and potential applications.     

Structural diversity in coordination chemistry of tridentate and tetradentate polyphosphines of Group 6 to 10 transition metal complexes

Tridentate and tetradentate polyphosphines offer a huge variety of coordination modes to transition metals which lead, depending on the metal, to very different structural features in the resulting complexes. Steric effects being crucial in metal–phosphine complexes reactivity, a good knowledge of the molecular structures of the species is required both in the solid state and in solution. This article reviews from a structural point of view the monometallic and symmetrical homobimetallic complexes of the transition elements of Group 6 to 10 with tridentate and tetradentate phosphines. Concerning the classical triphosphines and tetraphosphines, emphasis was put on advances reported after the year 1994, since comprehensive reviews have covered the former period. Several anterior relevant results are, however, briefly mentioned when necessary. A second part is devoted to nitrogen- and sulfur-containing derivatives potentially tridentate and tetradentate ligands, and their coordination to the above-mentioned metals. The last part describes the complexes obtained with the less classical ferrocenyl polyphosphine ligands or their nitrogen-containing derivatives: each ligand having a potential tridentate or tetradentate coordination from either phosphorus or nitrogen donor atoms. The literature cutoff date was during the second half of 2000, but in a few cases, references to important work appearing during 2001 were made; however such coverage should be completed in a future compilation. An exhaustive quoting of catalytic applications and reaction chemistry was beyond the scope of this article mainly devoted to structural works. Nevertheless, in order to illustrate the importance of this chemistry, efforts were made to provide the reader with recent references that have marked the field, even in the absence of X-ray structural characterization.     

On the Nature of Interactions between Ionic Liquids and Small Amino‐Acid‐Based Biomolecules

During the last decade, ionic liquids (ILs) have revealed promising properties and applications in many research fields, including biotechnology and biological sciences. The focus of this contribution is to give a critical review of the phenomena observed and current knowledge of the interactions occurring on a molecular basis. As opposed to the huge advances made in understanding the properties of proteins in ILs, complementary investigations dealing with interactions between ILs and peptides or oligopeptides are underrepresented and are mostly only of phenomenological nature. However, the field has received more attention in the last few years. This Review features a meta‐analysis of the available data and findings and should, therefore, provide a basis for a scientifically profound understanding of the nature and mechanisms of interactions between ILs and structured or nonstructured peptides. Fundamental aspects of the interactions between different peptides/oligopeptides and ILs are complemented by sections on the experimental (spectroscopy, structural biology) and theoretical (computational chemistry) possibilities to explain the phenomena reported so far in the literature. In effect, this should lead to the development of novel applications and support the understanding of IL–solute interactions in general.     

Nuclear magnetic resonance study of selected derivatives of 2,8,9-trioxa-5-aza-1-silatricyclo[3.3.3.01,5]undecane (silatrane)

The ¹H, ¹³C and ²⁹Si nuclear magnetic resonance spectra of the parent compound and twelve derivatives of 2,8,9-trioxa-5-aza-1-silatricyclo[3.3.3.0^1,5]undecane (silatrane) are discussed. Effective Taft polarity constants for the silatrane substituents are proposed. An equation is developed to correlate the ²⁹Si NMR chemical shifts of the silatranes with the corresponding organo-triethoxysilanes.