A5069457681- Advanced NMR Techniques and Applications
- Solid-state spectroscopy and crystallography
- NMR spectroscopy and applications
- Electron Spin Resonance Studies
- Atomic and Subatomic Physics Research
- Mesoporous Materials and Catalysis
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Zeolite Catalysis and Synthesis
- Muon and positron interactions and applications
- Quantum, superfluid, helium dynamics
- Magnetism in coordination complexes
- Advanced MRI Techniques and Applications
- Molecular spectroscopy and chirality
- Crystallography and molecular interactions
- Ferroelectric and Piezoelectric Materials
- Metal-Organic Frameworks: Synthesis and Applications
- Asymmetric Hydrogenation and Catalysis
- Advanced Battery Materials and Technologies
- Inorganic Fluorides and Related Compounds
- Physics of Superconductivity and Magnetism
- Multiferroics and related materials
- Spectroscopy and Quantum Chemical Studies
- Advanced Cellulose Research Studies
- Ionic liquids properties and applications
Technical University of Darmstadt
2016-2025
Institute of Inorganic Chemistry of the Slovak Academy of Sciences
2016-2020
Freie Universität Berlin
2000-2013
Centre National de la Recherche Scientifique
1998-2010
Friedrich Schiller University Jena
2005-2010
Université de Toulouse
2010
Université Toulouse III - Paul Sabatier
2010
Physikalisch-Technische Bundesanstalt
2005-2010
Laboratoire de Chimie de Coordination
1998-2010
Helmholtz Institute Jena
2005-2009
The adsorption of water in two mesoporous silica materials with cylindrical pores uniform diameter, MCM-41 and SBA-15, was studied by 1H MAS (MAS=magic angle spinning) static solid-state NMR spectroscopy. All observed hydrogen atoms are either surface -SiOH groups or hydrogen-bonded molecules. Unlike MCM-41, some strongly bound molecules exist at the inner surfaces SBA-15 that assigned to defects. At higher filling levels, a further difference between is observed. Water exhibit bimodal line...
The gas-phase loading of [Zn4O(bdc)3] (MOF-5; bdc = 1,4-benzenedicarboxylate) with the volatile compound [Ru(cod)(cot)] (cod 1,5-cyclooctadiene, cot 1,3,5-cyclooctatriene) was followed by solid-state (13)C magic angle spinning (MAS) NMR spectroscopy. Subsequent hydrogenolysis adsorbed complex inside porous structure MOF-5 at 3 bar and 150 degrees C performed, yielding ruthenium nanoparticles in a typical size range 1.5-1.7 nm, embedded intact matrix, as confirmed transmission electron...
Reversible field-induced phase transitions define antiferroelectric perovskite oxides and lay the foundation for high-energy storage density materials, required future green technologies. However, promising new antiferroelectrics are hampered by transition´s irreversibility low electrical resistivity. Here, we demonstrate an approach to overcome these problems adjusting local structure defect chemistry, delivering NaNbO3-based with well-defined double polarization loops. The attending...
The hydrogen bond interaction of pyridine with the silanol groups inner surfaces MCM-41 and SBA-15 ordered mesoporous silica has been studied by a combination solid-state NMR techniques. pore diameters were varied between 3 4 nm for 7 9 SBA-15. 1H MAS experiments performed under magic angle spinning (MAS) conditions in absence presence pyridine-d5 reveal that large majority are located surfaces, isolated from each other but able to form bonds pyridine. On hand, low- room-temperature 15N...
In the last fifteen years several novel porous silica materials, which are periodically structured on mesoscopic length scale, have been synthesized. They of broad interest for fundamental studies surface–substrate interactions, dynamics guest molecules in confinement and effect structural thermophysical properties fluids. Examples such effects include change freezing melting points or glass transitions confined liquids. These studied by combinations NMR techniques, as 15N- 2H-solid-state...
A novel single-source precursor was synthesized by the reaction of an allyl hydrido polycarbosilane (SMP10) and tetrakis(dimethylamido)hafnium(iv) (TDMAH) for purpose preparing dense monolithic SiC/HfC(x)N(1-x)-based ultrahigh temperature ceramic nanocomposites. The materials obtained at different stages synthesis process were characterized via Fourier transform infrared (FT-IR) as well nuclear magnetic resonance (NMR) spectroscopy. polymer-to-ceramic transformation investigated means MAS...
A good impression: modular approach using a ruthenium(II) catalyst during peptide synthesis gives rigid and well-defined triazole bridges as tailor-made substitutes for natural disulfide (see structures). The corresponding modification of the monocyclic sunflower trypsin inhibitor-1 yielded an equally potent peptidomimetic containing redox stable 1,5-disubstituted 1,2,3-triazole bridge.
Air-stable and homogeneous gold nanoparticles (AuNPs, 1a-5a) ligated by various secondary phosphine oxides (SPOs), [R(1)R(2)P(O)H] (R(1) = Naph, R(2) (t)Bu, L1; R(1) Ph, L2; L3; Et, L4; Cy, L5; L6), with different electronic steric properties were synthesized via NaBH4 reduction of the corresponding Au(I)-SPO complex. These easily accessible ligands allow formation well dispersed small (size 1.2-2.2 nm), which characterized use a wide variety techniques, such as transmission electron...
The interfacial adhesion design between "mortar" and "bricks" is essential for mechanical barrier performance of nanocellulose-based nacre-mimetic nanocomposites, especially at high moisture conditions. To address this fundamental challenge, dopamine (DA) has been conjugated to cellulose nanofibrils (CNFs) subsequently assembled with montmorillonite (MTM) generate layered nanocomposite films inspired by the strong mussel adhesive proteins inorganic surfaces under water. selective formation...
Amorphous SiHfBCN ceramics were prepared from a commercial polysilazane (HTT 1800, AZ-EM), which was modified upon reactions with Hf(NEt2)4 and BH3·SMe2, subsequently cross-linked pyrolyzed. The materials investigated respect to their chemical phase composition, by means of spectroscopy techniques (Fourier transform infrared (FTIR), Raman, magic-angle spinning nuclear magnetic resonance (MAS NMR)), as well X-ray diffraction (XRD) transmission electron microscopy (TEM). Annealing experiments...
By combining two different nitrile building blocks a synergistic increase in the CO<sub>2</sub> uptake mixed-nitrile CTFs over single-nitrile could be achieved.
Significance Magnetic resonance imaging is hindered by inherently low sensitivity, which limits the method for most part to observing water molecules in body. Hyperpolarized exhibit strongly enhanced MRI signals opens door low-concentration species vivo. Biomolecules can be hyperpolarized and injected into a patient allowing metabolism tracked real time, greatly expanding information available radiologist. Parahydrogen-induced polarization (PHIP) hyperpolarization renowned its cost...
Fundamental understanding of ion electroadsorption processes in porous electrodes on a molecular level provides important guidelines for next-generation energy storage devices like electric double layer capacitors (EDLCs). Porous carbons functionalized by heteroatoms show enhanced capacitive performance, but the underlying mechanism is still elusive, due to lack reliable tools precisely identify multiple N species and establish clear structure property relations. Here, we use advanced...
A novel series of hydrogen-bonded solid 1 : acid–base complexes 15N-labeled 2,4,6-trimethylpyridine (collidine) with carboxylic acids and their hydrogen bond deuterated analogs were synthesized studied by 1H magic angle spinning (MAS) 15N cross-polarization NMR without MAS. Not only zwitterionic the H-bond proton closer to nitrogen than oxygen but also molecular have been observed, where is located oxygen. For these complexes, isotropic chemical shifts shielding tensor elements measured (the...
Surface-reactive metal colloids: Ruthenium nanoparticles are able to accommodate hydrogen atoms at, or immediately below, their surface, as shown by a combination of liquid, gas-phase and solid-state NMR techniques. The mobile on the ruthenium particles—and reactive—which leads fast hydrogen–deuterium exchange with ligands (see graphic) even in solid state. Supporting information for this article is available WWW under http://www.wiley-vch.de/contents/jc_2267/2005/z400621_s.pdf from author....
Surface CC bond activation: Ruthenium nanoparticles prepared by hydrogenation of an organometallic precursor accommodate more than one hydride per surface ruthenium atom as well various ligands, such amines or phosphines, shown gas-phase, liquid, and solid-state NMR spectroscopy titration with olefins. These react ethylene at room temperature to give ethane surface-bound methyl species (see scheme). Supporting information for this article is available on the WWW under...
Novel materials based on sustainable with high absorption capacity are still rare for the separation of organic liquids or oil spills and water. In this report, ultra-light nanocomposite aerogels consisting bacterial cellulose (BC) graphene oxide (GO) were constructed after an eco-friendly freeze-drying process first time. Due to hydrophilic properties both highly porous structure, BC/GO could absorb not only liquids, such as cyclohexane DMF, but also Specific was achieved reduction GO using...
Abstract Lead-based relaxor ferroelectrics are key functional materials indispensable for the production of multilayer ceramic capacitors and piezoelectric transducers. Currently there strong efforts to develop novel environmentally benign lead-free materials. The structural origins state role composition modifications in these still not well understood. In present contribution, solid-solution (100- x )(Bi 1/2 Na )TiO 3 - BaTiO (BNT- BT), a prototypic is studied by combination solid-state...
We present a facile approach to encapsulate functional porous organic cages (POCs) into robust MOF by an incipient-wetness impregnation method. Porous cucurbit[6]uril (CB6) with high CO2 affinity were successfully encapsulated the nanospace of Cr-based MIL-101 while retaining crystal framework, morphology, and stability MIL-101. The CB6 amount is controllable. Importantly, as molecule intrinsic micropores smaller than inner mesopores MIL-101, more sites for are created in resulting...
Antiferroelectric materials exhibit a unique electric-field-induced phase transition, which enables their use in energy storage, electrocaloric cooling, and nonvolatile memory applications. However, many prototype antiferroelectrics this transition is irreversible, prevents implementation. In work, we demonstrate general approach to promote the reversibility of by targeted modification material's local structure. A new NaNbO3-based composition, namely (1–x)NaNbO3–xSrSnO3, was designed with...
For the first time, chemical exchange saturation transfer (CEST) nuclear magnetic resonance (NMR) is utilized to study short-lived hydride intermediates in catalytic cycle of an organometallic complex [Ir(IMes)(Py)3(H)2]Cl. These complexes are typically not observable by other NMR techniques because they low concentrated and undergo reversible ligand with main complex. The intermediate [Ir(Cl)(IMes)(Py)2(H)2] [Ir(CD3OD)(IMes)(Py)2(H)2] detected, assigned, characterized solution, situ at room...
Various cyclic carbonates were prepared by cycloaddition of carbon dioxide with different epoxides using imidazolium-based catalysts grafted on a mesoporous silica support through 3-aminopropyltrimethoxysilane and Br–(CH2)n–Br (n = 2 or 4) under efficient mild conditions. The characterized various physicochemical techniques such as magic angle spinning (MAS) NMR, 1H Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Field-emission scanning microscopy (FESEM),...