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Vadim G. Kessler

Bio: Vadim G. Kessler is an academic researcher from Swedish University of Agricultural Sciences. The author has contributed to research in topics: Alkoxide & Nanoparticle. The author has an hindex of 39, co-authored 284 publications receiving 5262 citations. Previous affiliations of Vadim G. Kessler include Bar-Ilan University & Center for Advanced Materials.


Papers
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Journal ArticleDOI
TL;DR: Application of the same synthetic approach to n-propoxide complexes offers in a Co-Ti system a derivative with a different composition and resolved metal and ligand disorder, Co(4)Ti(2)O(acac)(4)(O(n)Pr)(10) (6), which, however, still follows the Lindquist type and displays high (tetragonal) symmetry for both the molecule and the crystal structure.
Abstract: Interaction of M(acac)(2) with Ti(OEt)(4) associated with hydrolysis or thermolysis provides with high yields, through the decomposition of the initially formed M(2)Ti(2)(acac)(4)(OEt)(8), M = Ni (1), Co (2), poorly soluble Lindqvist-type products with the formula M(5)TiO(acac)(6)(OEt)(6), M = Ni (3), Co (4), Mg (5). The compounds 3-5 are isostructural and display a perfect statistical disorder between the OEt groups and 1/2 of the beta-diketonate, acac, ligand. The metal atoms constitute a regular octahedron, centered by the oxo-oxygen atom. There is only one symmetrically independent metal site, which imposes it to contain 1/6 of titanium and 5/6 of the divalent metal atom. The oxygen atoms on the surface of the octahedron are doubly bridging and are located above the twelve edges of the octahedron, as is usual for the Lindqvist-type structures. The coordination of the metal atoms is completed by a single terminal oxygen atom. The complexes 3-5 are volatile with decomposition, releasing only homometallic products into the gas phase in the case of 3 and 4, but with a considerable contribution of molecular evaporation in the case of 5. The intermediates 1 and 2 belong to the tetramolybdate, M(4)O(16), structure type. Highly soluble 1 and 2 can be considered as attractive molecular precursors for the incorporation of 3 and 4 into porous matrices for the preparation of combustion catalysts. Application of the same synthetic approach to n-propoxide complexes offers in a Co-Ti system a derivative with a different composition and resolved metal and ligand disorder, Co(4)Ti(2)O(acac)(4)(O(n)Pr)(10) (6), which, however, still follows the Lindquist type and displays high (tetragonal) symmetry for both the molecule and the crystal structure.

20 citations

Journal ArticleDOI
TL;DR: In this paper, a new route has been presented for synthesis of the individual crystalline mixed ligand precursor [Zr(OnPr)(OiPr)3(iPrOH)]2, from zirconium n-propoxide.
Abstract: Long-term storage at 0 °C of a paraffin-sealed flask with commercial 70 wt% solution of zirconium n-propoxide in n-propanol resulted in crystallization of an individual oxoalkoxide complex Zr4O(OnPr)14(nPrOH)2 in over 20% yield. The structure of this molecule can be described as a triangular Zr3(μ3-O)(OR)10(ROH) core of 3 edge-sharing octahedrons with an additional Zr(OR)4(ROH) unit attached through a pair of (μ-OR) bridges. Mass spectrometric and 1H NMR investigation of the commercial samples of the most broadly applied zirconium and hafnium n-propoxides and n-butoxides indicate the presence of analogous species in the commercial alkoxide precursors. The content of oxo-alkoxide species in the commercial precursors has been estimated to be ~20% for n-propoxide and ~35% for zirconium n-butoxide. A new route has been presented for synthesis of the individual crystalline mixed ligand precursor [Zr(OnPr)(OiPr)3(iPrOH)]2, from zirconium n-propoxide. A high yield has been observed (~90%), indicative of an almost complete precursor transformation. Mass spectrometry has shown that the synthesized mixed ligand precursor is dimeric, which makes it an attractive alternative to zirconium n-propoxide. Addition of 1 eq of Acetylacetone to zirconium or hafnium alkoxide precursors results in formation of dimeric [M(OR)3(acac)]2 in high yields. These species have limited stability (much higher for Hf than for Zr) and transform in solution into hydrolysis-insensitive M(acac)4 through very unstable M(acac)3(OR) intermediates containing 7-coordinated metal centers. This transformation can be followed kinetically in hydrocarbon solvents by 1H NMR and is noticeably accelerated by addition of parent alcohols. The obtained results clearly reveal limited applicability of EXAFS and XANES techniques for the study of such systems, especially in the context of structure prediction. Electronic supplementary material The online version of this article (doi:10.1007/s10971-009-1988-0) contains supplementary material, which is available to authorized users.

20 citations

Journal ArticleDOI
TL;DR: In this article, a tetranuclear titanium oxo complex containing the antibacterial agent triclosan is presented, which provides a good model for the interaction between tricloins and titania, which may be used for drug delivery applications.
Abstract: We present the structure of a new tetranuclear titanium oxo complex containing the antibacterial agent triclosan. This provides a good model for the interaction between triclosan and titania, which may be used for drug-delivery applications. The antibacterial activity of the hydrolyzed complex against Staphylococcus aureus is investigated. Thereafter, we use the obtained titanium oxo complex to demonstrate its susceptibility towards hydrolysis, contrary to the widespread belief that titanium oxo complexes are water-stable, and demonstrate that it transforms into titania (anatase) on contact with water. Both hydrolysis and thermolysis of the complex yield titania particles, of very uniform size and shape, that connect into 3D nanostructures; this is of interest for practical applications.

19 citations

Journal ArticleDOI
TL;DR: In this paper, a simple, one-stage, efficient synthetic method for the growth of carbon sausages filled with in situ formed tungsten oxide nanorods (CSTON), without any external catalyst, was reported.
Abstract: In this article, we report a simple, one-stage, efficient synthetic method for the growth of carbon sausages filled with in situ formed tungsten oxide nanorods (CSTON), without any external catalyst. The thermal dissociation of tungsten(VI) isopropoxide, 5% w/v in isopropanol at 700 °C in a closed Swagelok cell in an inert atmosphere yielded a CSTON product. The product is characterized by SEM, TEM, EDAX, C, H, N, S analysis, TGA, Raman spectroscopy, and HR-TEM. The assignment of the structure of the sausages as a carbon shell, with the central part being the WOx, is based on SAEDS spectra. The same reaction was also conducted at a lower temperature closer to the temperatures of solvothermal reactions, at 350 °C. The reaction yielded WOx nanorods with a diameter ranging from 10 nm to 50 nm and a length of up to 6 μm.

19 citations

Journal ArticleDOI
TL;DR: In this article, perovskite films (SrZrO3) were deposited on plane Si(1/0/0) substrates by direct liquid injection MOCVD from two original heterometallic precursors.

19 citations


Cited by
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TL;DR: This review summarizes the major progress in the field, including the principles that permit atomically precise synthesis, new types of atomic structures, and unique physical and chemical properties ofatomically precise nanoparticles, as well as exciting opportunities for nanochemists to understand very fundamental science of colloidal nanoparticles.
Abstract: Colloidal nanoparticles are being intensely pursued in current nanoscience research. Nanochemists are often frustrated by the well-known fact that no two nanoparticles are the same, which precludes the deep understanding of many fundamental properties of colloidal nanoparticles in which the total structures (core plus surface) must be known. Therefore, controlling nanoparticles with atomic precision and solving their total structures have long been major dreams for nanochemists. Recently, these goals are partially fulfilled in the case of gold nanoparticles, at least in the ultrasmall size regime (1–3 nm in diameter, often called nanoclusters). This review summarizes the major progress in the field, including the principles that permit atomically precise synthesis, new types of atomic structures, and unique physical and chemical properties of atomically precise nanoparticles, as well as exciting opportunities for nanochemists to understand very fundamental science of colloidal nanoparticles (such as the s...

2,144 citations

Journal ArticleDOI
TL;DR: This work focuses on the characterization of the phytochemical components of Lactide ROP and their role in the regulation of cell reprograming.
Abstract: 23 Stereocontrol of Lactide ROP 6164 231 Isotactic Polylactides 6164 232 Syndiotactic Polylactides 6166 233 Heterotactic Polylactides 6166 3 Anionic Polymerization 6166 4 Nucleophilic Polymerization 6168 41 Mechanistic Considerations 6168 42 Catalysts 6169 421 Enzymes 6169 422 Organocatalysts 6169 43 Stereocontrol of Lactide ROP 6170 44 Depolymerization 6170 5 Cationic Polymerization 6170 6 Conclusion and Perspectives 6171 7 Acknowledgments 6173 8 References and Notes 6173

2,014 citations

Journal ArticleDOI
TL;DR: Nonlinear Optical Characterizations of Multiphoton Active Materials 1282 5.2.1.
Abstract: 4. Survey of Novel Multiphoton Active Materials 1257 4.1. Multiphoton Absorbing Systems 1257 4.2. Organic Molecules 1257 4.3. Organic Liquids and Liquid Crystals 1259 4.4. Conjugated Polymers 1259 4.4.1. Polydiacetylenes 1261 4.4.2. Polyphenylenevinylenes (PPVs) 1261 4.4.3. Polythiophenes 1263 4.4.4. Other Conjugated Polymers 1265 4.4.5. Dendrimers 1265 4.4.6. Hyperbranched Polymers 1267 4.5. Fullerenes 1267 4.6. Coordination and Organometallic Compounds 1271 4.6.1. Metal Dithiolenes 1271 4.6.2. Pyridine-Based Multidentate Ligands 1272 4.6.3. Other Transition-Metal Complexes 1273 4.6.4. Lanthanide Complexes 1275 4.6.5. Ferrocene Derivatives 1275 4.6.6. Alkynylruthenium Complexes 1279 4.6.7. Platinum Acetylides 1279 4.7. Porphyrins and Metallophophyrins 1279 4.8. Nanoparticles 1281 4.9. Biomolecules and Derivatives 1282 5. Nonlinear Optical Characterizations of Multiphoton Active Materials 1282

1,864 citations

Journal ArticleDOI
TL;DR: Chemistries that Facilitate Nanotechnology Kim E. Sapsford,† W. Russ Algar, Lorenzo Berti, Kelly Boeneman Gemmill,‡ Brendan J. Casey,† Eunkeu Oh, Michael H. Stewart, and Igor L. Medintz .
Abstract: Chemistries that Facilitate Nanotechnology Kim E. Sapsford,† W. Russ Algar, Lorenzo Berti, Kelly Boeneman Gemmill,‡ Brendan J. Casey,† Eunkeu Oh, Michael H. Stewart, and Igor L. Medintz*,‡ †Division of Biology, Department of Chemistry and Materials Science, Office of Science and Engineering Laboratories, U.S. Food and Drug Administration, Silver Spring, Maryland 20993, United States ‡Center for Bio/Molecular Science and Engineering Code 6900 and Division of Optical Sciences Code 5611, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States College of Science, George Mason University, 4400 University Drive, Fairfax, Virginia 22030, United States Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Sacramento, California 95817, United States Sotera Defense Solutions, Crofton, Maryland 21114, United States

1,169 citations