A5063943287- Advanced NMR Techniques and Applications
- Photosynthetic Processes and Mechanisms
- Spectroscopy and Quantum Chemical Studies
- Zeolite Catalysis and Synthesis
- Advanced MRI Techniques and Applications
- Metal-Organic Frameworks: Synthesis and Applications
- NMR spectroscopy and applications
- Synthesis and Properties of Aromatic Compounds
- Methane Hydrates and Related Phenomena
- Electron Spin Resonance Studies
- X-ray Diffraction in Crystallography
- Magnetism in coordination complexes
- Mesoporous Materials and Catalysis
- Light effects on plants
- Thermochemical Biomass Conversion Processes
- Microfluidic and Capillary Electrophoresis Applications
- Covalent Organic Framework Applications
- Crystallization and Solubility Studies
- Enzyme-mediated dye degradation
- Porphyrin and Phthalocyanine Chemistry
- Photoreceptor and optogenetics research
- Metal-Catalyzed Oxygenation Mechanisms
- Metabolomics and Mass Spectrometry Studies
- Supramolecular Self-Assembly in Materials
- Electrochemical Analysis and Applications
Leiden University
2015-2025
Huygens Institute for History and Culture of the Netherlands
2020
Railenium
2015
Chlorosomes, the photosynthetic antenna complexes of green sulfur bacteria, are paradigms for light-harvesting elements in artificial designs, owing to their efficient energy transfer without protein participation. We combined magic angle spinning (MAS) NMR, optical spectroscopy and cryogenic electron microscopy (cryo-EM) characterize structure chlorosomes from a
High temperature/pressure in situ Attenuated Total Reflection Infrared (ATR-IR) spectroscopy was used to investigate the phase transformation of support γ-Al2O3 into boehmite (AlO(OH)) under hydrothermal conditions aqueous reforming (APR). Activation energy barriers formation hot compressed water at temperatures between 150 and 180 °C were calculated be 15.9 ± 4.8 kJ mol(-1) for 43.2 4.3 Pt/γ-Al2O3. The influence Pt particles is suggested slow down by selective blockage surface nucleation...
The cyanobacterial phytochrome Cph1 can be photoconverted between two thermally stable states, Pr and Pfr. photochemically induced Pfr --> back-reaction has been followed at low temperature by magic-angle spinning (MAS) NMR spectroscopy, allowing intermediates, Lumi-F Meta-F, to trapped. Employing uniformly (13)C- (15)N-labeled open-chain tetrapyrrole chromophores, all four states-Pfr, Lumi-F, Pr-have structurally characterized. In the first step, double bond photoisomerization forming...
Photo-CIDNP (photochemically induced dynamic nuclear polarization) can be observed in frozen and quinone-blocked photosynthetic reaction centers (RCs) as modification of magic-angle spinning (MAS) NMR signal intensity under illumination. Studying the carotenoidless mutant strain R26 Rhodobacter sphaeroides, we demonstrate by experiment theory that contributions to spin polarization from three-spin mixing differential decay mechanism separated generated radical pair mechanism, which is...
A mild and safe chloromethylation of metal–organic frameworks is presented. After this post-synthetic functionalization, chlorine can be substituted by a wide range moieties to obtain various multifunctional materials. The method in principle extended coordination polymers with exposed aromatic rings.
Despite a growing understanding of factors that drive monomer self-assembly to form supramolecular polymers, the effects aromaticity gain have been largely ignored. Herein, we document in two different modes squaramide-based bolaamphiphiles. Importantly, O → S substitution squaramide synthons resulted polymers with increased fiber flexibility and lower degrees polymerization. Computations spectroscopic experiments suggest oxo- thiosquaramide bolaamphiphiles self-assemble into "head-to-tail"...
In contrast to the common viewpoint that bacteriochlorophyll (BChl) motion is largely absent within chlorosome assembly, physics-based modeling points a crucial role of nanoscale librational macrocycle for transfer excitons. To elucidate this experimentally, compositional uniformity and high sensitivity are required. We focused on uniformly 13C labeled preparations from bchQ mutant Chlorobaculum tepidum with significantly enhanced structural homogeneity. The characterized using Rotational...
Abstract In situ upgrading of biomass pyrolysis vapours over Na 2 CO 3 /γ‐Al O catalysts was studied in a laboratory‐scale fixed‐bed reactor at 500 °C. Catalytic oil exhibits significant improvement its non‐catalytic counterpart, such as lower oxygen content (12.3 wt % compared to 42.1 %), higher energy density (37.0 19.0 MJ kg −1 ) and acidity. A study using thermogravimetry–mass spectrometry analysis 23 1 H magic‐angle spinning NMR techniques has revealed the formation new sodium species...
Abstract The synthesis, characterization, sulfonation, and catalytic performance of two new porous aromatic frameworks are presented. polymers, which were obtained by the Suzuki–Miyaura cross‐coupling commercially available precursors 1,3,5‐ tris (4‐bromophenyl)benzene or (4‐bromophenyl)amine benzene‐1 4‐diboronic acid, only contain sp 2 C−C C−N bonds, display excellent thermal chemical stability, allow for post‐synthetic functionalization under very harsh reaction conditions. Upon treatment...
Delayed graft function is the manifestation of ischemia reperfusion injury in context kidney transplantation. While hundreds interventions successfully reduce experimental models, all clinical have failed. This explorative evaluation examined possible metabolic origins combining data from 18 pre- and post-reperfusion tissue biopsies with 36 sequential arteriovenous blood samplings over three study groups. These groups included living deceased donor grafts without delayed function. Group...
The largest light-harvesting antenna in nature, the chlorosome, is a heterogeneous helical BChl self-assembly that has evolved green bacteria to harvest light for performing photosynthesis low-light environments. Guided by NMR chemical shifts and distance constraints Chlorobaculum tepidum wild-type chlorosomes, two contrasting packing modes syn-anti parallel stacks of c form polar 2D arrays, with dipole moments adding up, are explored. Layered assemblies were optimized using local orbital...
Bioactivity-guided fractionation of the EtOH extract branches Kielmeyera variabilis led to isolation a new acylphoroglucinol (1), which was active against all MRSA strains tested herein, with pronounced activity strain EMRSA-16. Compound 1 displayed an MIC 0.5 mg/L as compared 128 for control antibiotic norfloxacin. The structure compound elucidated by 1D and 2D NMR spectroscopic analysis mass spectrometry, experimental calculated ECD were used determine absolute configurations. compounds...
Interactions between plants and the soil's microbial & fungal flora are crucial for health of soil ecosystems food production. Microbe-plant interactions difficult to investigate in situ due their intertwined relationship involving morphology metabolism. Here, we describe an approach overcome this challenge by elucidating metabolic profile Medicago truncatula root nodules using Magnetic Resonance (MR) Microscopy, at highest magnetic field strength (22.3 T) currently available imaging. A...
The trinuclear copper center (TNC) of laccase reduces oxygen to water with very little overpotential. arrangement the coppers and ligands in TNC is known be from many crystal structures, yet information about possible dynamics absent. Here, we report at small Streptomyces coelicolor using paramagnetic NMR electron resonance spectroscopy. Fermi contact-shifted resonances tentatively assigned histidine Hδ1 display a two-state chemical exchange rates order 100 s-1. In spectra, least two forms...
Abstract Incorporation of new functionalities into metal–organic frameworks (MOFs) by post‐synthetic modification is a most attractive strategy for attaining the desired properties without risking destruction crystalline structure chosen aimed application. In this work amine group in NH 2 ‐MIL‐53(Al) was used as anchoring point diphenylphosphinyl (Ph PO–) moiety. The success derivatization confirmed 31 P MAS NMR and DRIFT spectroscopic studies. A newly synthesized reference linker bearing...
Polymeric nanoparticles (NPs) find many uses in nanomedicine, from drug delivery to imaging. In this regard, poly (lactic-co-glycolic acid) (PLGA) and polyethylene glycol (PEG) particles are the most widely applied types of nano-systems due their biocompatibility biodegradability. Here we developed novel fluorinated polymeric NPs as vectors for multi-modal nanoprobes. This approach involved modifying with trifluoroacetamide (TFA) loading them a near-infrared (NIR) dye different imaging...
Despite the high structural symmetry of cofactor arrangement and protein environment, light-induced electron transfer in photosynthetic reaction centers (RCs) purple bacterium Rhodobacter sphaeroides runs selectively over one two branches cofactors. The origin this functional break has been debated for several decades. Recently, a crucial role substituents proposed by theoretical studies [Yamasaki, H.; Takano, Y.; Nakamura, H. J. Phys. Chem. B 2008, 112, 13923–13933]. Photo-CIDNP...
Abstract Plants adapt to fluctuating light conditions by a process called non-photochemical quenching (NPQ), where membrane protein PsbS plays crucial role and transforms change in the pH-gradient across thylakoid under excess into photoprotective state, leading de-excitation of antenna chlorophylls. The activation mechanism is elusive has been proposed involve monomerization step protonation specific residues. To elucidate its function, it essential produce large quantities, stabilize...