A5087063683- Advanced NMR Techniques and Applications
- NMR spectroscopy and applications
- Solid-state spectroscopy and crystallography
- Zeolite Catalysis and Synthesis
- Mesoporous Materials and Catalysis
- Catalytic Processes in Materials Science
- Hydrogen Storage and Materials
- X-ray Diffraction in Crystallography
- Advanced MRI Techniques and Applications
- Crystallization and Solubility Studies
- Chemical Synthesis and Characterization
- Ammonia Synthesis and Nitrogen Reduction
- Muon and positron interactions and applications
- Catalysis and Oxidation Reactions
- Metal-Organic Frameworks: Synthesis and Applications
- Atomic and Subatomic Physics Research
- Asymmetric Hydrogenation and Catalysis
- Advanced Chemical Physics Studies
- Advanced Battery Materials and Technologies
- Electron Spin Resonance Studies
- Polyoxometalates: Synthesis and Applications
- Catalysis and Hydrodesulfurization Studies
- Nanomaterials for catalytic reactions
- Ionic liquids properties and applications
- Electrocatalysts for Energy Conversion
Ames National Laboratory
2013-2022
Iowa State University
2013-2022
United States Department of Energy
1994-2018
Northwestern University
2018
Centrum Badań Molekularnych i Makromolekularnych Polskiej Akademii Nauk
2013
École Polytechnique Fédérale de Lausanne
2013
Marymount University
2013
Reliance Industries (India)
2007
Indian Institute of Technology Bombay
2007
National Chemical Laboratory
2007
A series of new mesoporous silica materials with MCM-41 type structure containing a homogeneous layer organic functional groups inside the pores was prepared using co-condensation method under low surfactant concentration condition. This reproducible synthetic approach resulted in high surface coverage several such as primary amine, secondary urea, isocyanate, vinyl, and nitrile. In addition, presence organoalkoxysilane precursors during base catalyzed condensation greatly influenced final...
Our civilization relies on synthetic polymers for all aspects of modern life; yet, inefficient recycling and extremely slow environmental degradation plastics are causing increasing concern about their widespread use. After a single use, many these materials currently treated as waste, underutilizing inherent chemical energy value. In this study, energy-rich polyethylene (PE) macromolecules catalytically transformed into value-added products by hydrogenolysis using well-dispersed Pt...
A team effort: Mesoporous silica nanosphere (MSN) materials bifunctionalized with a general acid group and base in various relative concentrations are described shown to function as cooperative catalytic systems. The turnover numbers observed indicate that the groups can activate substrates cooperation catalyze reactions involve carbonyl activation (see picture).
A systematic study of the surface MCM-41-type mesoporous silica nanoparticles prepared under low surfactant concentration was carried out using high-resolution solid-state nuclear magnetic resonance spectroscopy. The structures and concentrations various species present during dehydration rehydration silicas between -25 500 degrees C were detailed by employing one-dimensional two-dimensional (1)H, (13)C, (29)Si NMR, including (1)H signal intensity measurements, (1)H-(1)H homonuclear...
We have synthesized a poly(lactic acid) coated MCM-41-type mesoporous silica nanosphere (PLA-MSN) material can serve as fluorescence sensor system for detection of amino-containing neurotransmitters in neutral aqueous buffer. Utilizing the PLA layer gatekeeper, we investigated molecular recognition events between several structurally simple neurotransmitters, i.e., dopamine, tyrosine, and glutamic acid pore surface-anchored o-phthalic hemithioacetal (OPTA) group, which functions...
We describe the nearly quantitative preparation of phosphorus ylides and Wittig reaction occurring in solid sate during high-energy mechanochemical processing. Initial insights into details discovered chemical transformations indicate that mechanical processing supports interaction reacting centers by breaking crystallinity reactants providing mass transfer without a solvent.
ADVERTISEMENT RETURN TO ISSUEViewpointNEXTDynamic Nuclear Polarization Solid-State NMR in Heterogeneous Catalysis ResearchTakeshi Kobayashi†, Frédéric A. Perras†, Igor I. Slowing†‡, Aaron D. Sadow†‡, and Marek Pruski*†‡View Author Information† U.S. DOE Ames Laboratory, Ames, Iowa 50011-3020, United States‡ Department of Chemistry, State University, States*E-mail: [email protected]Cite this: ACS Catal. 2015, 5, 12, 7055–7062Publication Date (Web):October 20, 2015Publication History Received14...
A series of bifunctionalized mesoporous silica nanosphere-based (MSN) heterogeneous catalysts for the nitroaldol (Henry) reaction have been synthesized. common 3-[2-(2-aminoethylamino)ethylamino]propyl (AEP) primary group and three different secondary groups, ureidopropyl (UDP), mercaptopropyl (MP), allyl (AL) functionalities, were incorporated to these materials by introducing equal amounts AEP-trimethoxysilane with UDP-, MP-, or AL-trialkoxysilane precursors our previously reported...
A new nucleophilic catalytic system comprised of dialkylaminopyridine-functionalized mesoporous silica nanosphere (DMAP-MSN) has been synthesized and characterized. We have demonstrated that this material is an efficient heterogeneous catalyst for Baylis-Hillman, acylation, silylation reactions with good reactivity, product selectivity, recyclability. envision DMAP-functionalized can also serve as effective many other reactions.
Due to its extremely low natural abundance and quadrupolar nature, the (17)O nuclide is very rarely used for spectroscopic investigation of solids by NMR without isotope enrichment. Additionally, applicability dynamic nuclear polarization (DNP), which leads sensitivity enhancements 2 orders magnitude, wrought with challenges due lack spin diffusion transfer efficiency from (1)H. Here, we demonstrate new DNP-based measurements that extend solid-state beyond current capabilities. The use...
We show that dynamic nuclear polarization (DNP) can be used to enhance NMR signals of 13C and 29Si nuclei located in mesoporous organic/inorganic hybrid materials, at several hundreds nanometers from stable radicals (TOTAPOL) trapped the surrounding frozen disordered water. The approach is demonstrated using silica nanoparticles (MSN), functionalized with 3-(N-phenylureido)propyl (PUP) groups, filled surfactant cetyltrimethylammonium bromide (CTAB). DNP-enhanced proton magnetization...
Ultrawideline dynamic nuclear polarization (DNP)-enhanced 195Pt solid-state NMR (SSNMR) spectroscopy and theoretical calculations are used to determine the coordination of atomic Pt species supported within pores metal–organic frameworks (MOFs). The SSNMR spectra, with breadths reaching 10 000 ppm, were obtained by combining DNP broadbanded cross-polarization CPMG acquisition. Although enhancements in static samples lower than those typically observed under magic-angle spinning conditions,...
A synthetic method has been developed that can control both multifunctionalization and morphology of the mesoporous organic-inorganic hybrid materials by introducing different molar ratios organoalkoxysilane precursors to a base-catalyzed co-condensation silicate.
The first indirectly detected 13C−1H solid-state NMR correlation spectra of species bound to a surface are reported. experiments were performed at 14.1 T under fast (40 kHz) MAS. sensitivity gain was demonstrated on mesoporous silica sample containing approximately 300 μg covalently allyl groups, in the absence templating molecules and without isotope enrichment. A well-resolved two-dimensional spectrum acquired 15 min, which is more than 10 times faster using direct detection 13C nuclei.
Abstract A series of poly( N ‐isopropylacrylamide)‐coated mesoporous silica nanoparticle materials (PNiPAm‐MSNs) has been synthesized by a surface‐initiated living radical polymerization with reversible addition–fragmentation chain transfer (RAFT) reaction. The structure and the degree PNiPAm‐MSNs characterized variety techniques, including nitrogen sorption analysis, 29 Si 13 C solid‐state NMR spectroscopy, transmission electron microscopy (TEM), powder X‐ray diffraction (XRD). thermally...
A polyalkynylene-based conducting polymer (molecular wire) has been synthesized within the Cu-functionalized mesoporous MCM-41 silica catalyst. Fluorescence and 13C solid-state NMR provided spectroscopic evidence that synthesis of extended polymeric chains with a high degree alignment requires homogeneously distributed catalytic sites throughout entire MCM matrix. This type homogeneity achieved via co-condensation groups in narrow pores. In addition, our results indicated proper adjustment...
A combination of solid-state NMR techniques and theoretical calculations confirmed that unsubstituted metal-free corroles form supramolecular systems with toluene through π–π interactions in the solid state. Ultrafast magic angle spinning (MAS) enabled use 1H–1H homonuclear correlation spectroscopy to explore those intermolecular for which heteronuclear methods were difficult apply. As a service our authors readers, this journal provides supporting information supplied by authors. Such...
The hydroboration of aldehydes and ketones using a silica-supported zirconium catalyst is reported. Reaction Zr(NMe2)4 mesoporous silica nanoparticles (MSN) provides the catalytic material Zr(NMe2)n@MSN. Exhaustive characterization Zr(NMe2)n@MSN with solid-state (SS)NMR infrared spectroscopy, as well through reactivity studies, suggests its surface structure primarily ≡SiOZr(NMe2)3. presence these nitrogen-containing sites supported by 15N NMR including natural abundance measurements dynamic...
We systematically studied the enhancement factor (per scan) and sensitivity unit time) in (13)C (29)Si cross-polarization magic angle spinning (CP-MAS) NMR boosted by dynamic nuclear polarization (DNP) of functionalized mesoporous silica nanoparticles (MSNs). Specifically, we separated contributions due to: (i) microwave irradiation, (ii) quenching paramagnetic effects, (iii) presence frozen solvent, (iv) temperature, as well changes (v) relaxation (vi) behaviour. No line-broadening effects...
Organozirconium complexes are chemisorbed on Brønsted acidic sulfated ZrO2 (ZrS), Al2O3 (AlS), and ZrO2–WO3 (ZrW). Under mild conditions (25 °C, 1 atm H2), the supported Cp*ZrMe3, Cp*ZrBz3, Cp*ZrPh3 catalysts very active for benzene hydrogenation with activities declining decreasing acidity, ZrS ≫ AlS ≈ ZrW, arguing that more oxides (those having weaker corresponding conjugate bases) yield stronger surface organometallic electrophiles this reason have higher activity. Benzene selective...
Heterogeneous Brønsted acid catalysts are tremendously important in industry, particularly catalytic cracking processes. Here we show that these sites can be directly observed at natural abundance by 17 O DNP surface-enhanced NMR spectroscopy (SENS). We additionally the O-H bond length measured with sub-picometer precision, to enable a direct structural gauge of lability protons given material, which is correlated pH zero point charge material. Experiments performed on materials impregnated...