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.

Molecular Precursor Role in the Synthesis of ZrMVI2O8, MVI = Mo, W: Isolation and Properties of Zr3Mo8O24(OiPr)12(iPrOH)4

Abstract: The studies of zirconium isopropoxide solvate, Zr(OiPr)4·iPrOH(I), interaction with molybdenum oxoisopropoxide in different solvents (HOiPr, hexane) revealed I to be the only isolable crystalline product in alcohol In hexane I crystallized from Zr-rich solutions (up to Zr : Mo = 1 : 2 ratio) From the solutions with Zr : Mo = 1 : 2 ratio repeatedly dried in vacuo and subsequently redissolved in hexane, the crystallization of Zr3Mo8O24(OiPr)12(iPrOH)4(II) occurred slowly with 12% yield II can be recrystallized from hexane, but is destroyed by iPrOH which causes the formation of I Thermal decomposition of II in air at 800°C (2 h) gives a single phase ZrMo2O8(III) Hydrolysis studies of hexane solutions, prepared in a manner analogous to those, from which II was obtained, showed that single-phase samples of III could be obtained when a thin layer of solution was left for hydrolysis and evaporation of solvent in a moist air and then annealed at 800°C (2 h) The same kind annealing of a xerogel, obtained by hydrolysis with water solutions in iPrOH and subsequent drying at 100°C gave a complex mixture of phases where III was not even the major component No Zr-W complex was isolable under analogous conditions From the xerogel, obtained by hydrolysis with H2O/iPrOH, ZrO2 and WO3 crystallized separately on heating Only traces of ZrW2O8(IV) were obtained along with individual oxides when 1% water in ether was applied for hydrolysis Molecular precursor is therefore crucial for obtaining III, IV

One-pot synthesis of mesoporous SBA-15 containing protonated 3-aminopropyl groups

Abstract: A new technique of synthesis of mesoporous silica with protonated amino groups avoiding microwave treatment of mesophase was developed using a template method. The block-copolymer P123 was used as a template and sodium meta-silicate with 3-aminopropyltriethoxysilane as precursors. After the removal of template from mesophase with boiling ethanol, the obtained sample displayed highly ordered hexagonal structure with attractive textural parameters: SBET = 460 m2 g−1, Vtotal = 0.79 cm3g−1 and d = 7.1 nm. FTIR and 13C CP/MAS NMR spectroscopy revealed the presence of alkyl ammonium groups (0.7 mmol g−1) that were able to attach anions of molybdophosphoric acid to the surface of the synthesized mesoporous material. The resulting anion-ion exchange phase can find applications in many areas (adsorption, catalysis, etc.).

Hybrid Spider Silk with Inorganic Nanomaterials

Abstract: High-performance functional biomaterials are becoming increasingly requested. Numerous natural and artificial polymers have already demonstrated their ability to serve as a basis for bio-composites. Spider silk offers a unique combination of desirable aspects such as biocompatibility, extraordinary mechanical properties, and tunable biodegradability, which are superior to those of most natural and engineered materials. Modifying spider silk with various inorganic nanomaterials with specific properties has led to the development of the hybrid materials with improved functionality. The purpose of using these inorganic nanomaterials is primarily due to their chemical nature, enhanced by large surface areas and quantum size phenomena. Functional properties of nanoparticles can be implemented to macro-scale components to produce silk-based hybrid materials, while spider silk fibers can serve as a matrix to combine the benefits of the functional components. Therefore, it is not surprising that hybrid materials based on spider silk and inorganic nanomaterials are considered extremely promising for potentially attractive applications in various fields, from optics and photonics to tissue regeneration. This review summarizes and discusses evidence of the use of various kinds of inorganic compounds in spider silk modification intended for a multitude of applications. It also provides an insight into approaches for obtaining hybrid silk-based materials via 3D printing.

Can alcohol interchange provide the homoleptic niobium isopropoxide

Abstract: Niobium isopropoxide, Nb(OPr)5, is an attractive precursor of simple and complex niobium oxides in sol-gel technology. This compound cannot, unfortunately, be obtained by alcohol interchange starting from linear chain homologues such as Nb(OMe)5 or Nb(OEt)5. The equilibrium in the latter reaction favours formation of mixed-ligand complexes, [Nb2(OR)2(O Pr)8], R = Me, Et. In particular, [Nb2(OMe)2(OPr )8] (1) has been isolated in high yield from repeated treatment of Nb2(OMe)10 with excess of isopropanol. The X-ray single crystal study reveals a dinuclear structure containing a pair of edge-sharing octahedra with methoxide ligands in the bridging position. Infrared (IR) and mass spectroscopy (MS) studies confirmed the incomplete ligand substitution. The HNMR spectra suggest equilibrium between different molecular forms in solution. Solvothermal interaction of 1 with La chips in toluene/isopropanol media results in formation of a mixture of LaNb2(O Pr)13 and La2Nb4(l4– O)4(OH)2(l–O Pr)8(O Pr)8 (2).

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