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.

Synthesis and Structure of the First FeII Heterometallic Alkoxide [(THF)NaFe(OtBu)3]2 − a Possible Precursor for New Materials

Abstract: The reaction of FeBr2 with three equivalents of NaOtBu in THF affords the first heterometallic FeII alkoxide, [(THF)NaFe(OtBu)3]2 (1), to be structurally characterised. The central core of the structure is an M2O6M′2 fragment with C2 symmetry. The compound is shown to be promising as a new precursor for magnetic iron oxide Fe3O4. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Visualization of custom-tailored iron oxide nanoparticles chemistry, uptake, and toxicity.

Abstract: Nanoparticles of iron oxide generated by wearing of vehicles have been modelled with a tailored solution of size-uniform engineered magnetite particles produced by the Bradley reaction, a solvothermal metal–organic approach rendering hydrophilic particles. The latter does not bear any pronounced surface charge in analogy with that originating from anthropogenic sources in the environment. Physicochemical properties of the nanoparticles were thoroughly characterized by a wide range of methods, including XPD, TEM, SEM, DLS and spectroscopic techniques. The magnetite nanoparticles were found to be sensitive for transformation into maghemite under ambient conditions. This process was clearly revealed by Raman spectroscopy for high surface energy magnetite particles containing minor impurities of the hydromaghemite phase and was followed by quantitative measurements with EXAFS spectroscopy. In order to assess the toxicological effects of the produced nanoparticles in humans, with and without surface modification with ATP (a model of bio-corona formed in alveolar liquid), a pathway of potential uptake and clearance was modelled with a sequence of in vitro studies using A549 lung epithelial cells, lymphocyte 221-B cells, and 293T embryonal kidney cells, respectively. Raman microscopy unambiguously showed that magnetite nanoparticles are internalized within the A549 cells after 24 h co-incubation, and that the ATP ligand is retained on the nanoparticles throughout the uptake process. The toxicity of the nanoparticles was estimated using confocal fluorescence microscopy and indicated no principal difference for unmodified and modified particles, but revealed considerably different biochemical responses. The IL-8 cytokine response was found to be significantly lower for the magnetite nanoparticles compared to TiO2, while an enhancement of ROS was observed, which was further increased for the ATP-modified nanoparticles, implicating involvement of the ATP signalling pathway in the epithelium.

Homo- and hetero-metallic rhenium oxomethoxide complexes with a M4(μ-O)2(μ-OMe)4 planar core—a new family of metal alkoxides displaying a peculiar structural disorder. Preparation and X-ray single crystal study

Abstract: The reaction of Re2O7 with MeOH at room temperature leads to a fine black powder. A product with the same crystal structure, according to X-ray powder data, was obtained in the form of single crystals on storage of solutions of Re2O3(OMe)6, obtained by anodic oxidation of Re metal. It was identified as Re4O6(OMe)12 (1) by an X-ray single crystal study. A mixed-valence complex of analogous composition and structure, Re4O6 − y(OMe)12 + y (2), earlier erroneously described as Re4O2(OMe)16, can be obtained via anodic dissolution of Re in MeOH using high current densities. The heterometallic members of this family, Re4 − xMxO6 − y(OMe)12 + y [M = Mo (3), W (4); x ≤ 0.55, y < 1.0], were obtained by interaction of Re2O7 with MO(OMe)4 or M(OMe)6 in toluene at reflux. Mo-poor samples of 3 (x ≤ 0.25) could also be obtained on storage of solutions prepared by anodic oxidation of Re in the presence of MoO(OMe)4. The reaction of Re2O7 with Nb(OMe)5 or Ta(OMe)5 in refluxing toluene gave M4(μ-O)2(μ-OMe)4(OMe)14(ReO4)2 [M = Nb (5), Ta (6)] as the only crystalline products. The compounds 1–6 are insoluble in organic solvents and display a remarkable resistance to ambient atmosphere, making them attractive precursors for soft chemical preparation of rhenium metal and alloy powders.

Toward Molecular Recognition of REEs: Comparative Analysis of Hybrid Nanoadsorbents with the Different Complexonate Ligands EDTA, DTPA, and TTHA.

Abstract: Highly efficient tailored SiO2-based nanoadsorbents were synthesized for the selective extraction of rare-earth elements (REEs). Three different complexonates (EDTA, DTPA, and TTHA) were investigated in terms of uptake capacity and selectivity, showing capacities of up to 300 mg of RE3+/g and distinct preferential trends depending on the complexonate. EDTA-functionalized nanoadsorbents showed higher uptake for Dy3+, DTPA-functionalized ones for Nd3+, and TTHA-functionalized ones for La3+. The selectivity was even more pronounced in desorption at pH 3, with separation factors of up to 76 in ternary mixtures. A broad comparative study of single-crystal structures of the complexes between REE and the nongrafted complexonates at different pHs led to a molecular understanding of their individual modes of action. EDTA-derived nanoadsorbents combine concerted action and chelation, whereas the latter is the preferential coordination mechanism for DTPA- and TTHA-derived nanoadsorbents. These different mechanisms r...

Atomically Precise Colloidal Metal Nanoclusters and Nanoparticles: Fundamentals and Opportunities

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...

Controlled ring-opening polymerization of lactide and glycolide.

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

Multiphoton Absorbing Materials : Molecular Designs, Characterizations, and Applications

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

Functionalizing nanoparticles with biological molecules: developing chemistries that facilitate nanotechnology.

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