A5017198735- Photosynthetic Processes and Mechanisms
- Porphyrin and Phthalocyanine Chemistry
- Microbial Fuel Cells and Bioremediation
- Spectroscopy and Quantum Chemical Studies
- Porphyrin Metabolism and Disorders
- Electrocatalysts for Energy Conversion
- Hemoglobin structure and function
- Metalloenzymes and iron-sulfur proteins
- Metal-Catalyzed Oxygenation Mechanisms
- Radioactive element chemistry and processing
- CO2 Reduction Techniques and Catalysts
- Geochemistry and Elemental Analysis
- Microbial Community Ecology and Physiology
- Blood disorders and treatments
- Pneumocystis jirovecii pneumonia detection and treatment
- Enzyme Structure and Function
- Protein Structure and Dynamics
- Photochemistry and Electron Transfer Studies
- Photoreceptor and optogenetics research
- Immunodeficiency and Autoimmune Disorders
- Force Microscopy Techniques and Applications
- Molecular Junctions and Nanostructures
- TiO2 Photocatalysis and Solar Cells
- Iron oxide chemistry and applications
- Analytical chemistry methods development
James Madison University
2015-2024
Carrier (United States)
2019-2020
Argonne National Laboratory
2012-2015
Alex's Lemonade Stand Foundation
2014
University of Illinois Urbana-Champaign
2010-2011
University of Illinois System
2010
Pair distribution function (PDF) analysis was applied for structural characterization of the cobalt oxide water-splitting catalyst films using high energy X-ray scattering. The found to be composed domains consistent with a dioxide lattice sheet structure, possibly containing Co4O4 cubane-type "defect". identifies film consist 13–14 atoms distorted coordination geometries that can modeled by alteration in terminal oxygen atom positions at domain edge. Phosphate is seen as disordered...
Cu complexes as photosensitizers: Photoinduced charge-transfer dynamics from a copper(I) diimine complex to TiO2 nanoparticles were investigated by combining multiple time-resolved spectroscopic methods. An efficient and ultrafast electron transfer process the singlet MLCT state was discovered result of structural control owing flattening tetrahedral geometry in bulky groups ligands. Detailed facts importance specialist readers are published "Supporting Information". Such documents...
We report the first application of cyclometalated ruthenium complexes type Ru[(N∧N)2(C∧N)]+ as sensitizers for p-type NiO dye-sensitized solar cells (NiO p-DSCs). These dyes exhibit broad absorption in visible region. The carboxylic anchoring group is attached to phenylpyridine ligand, which results efficient hole injection. Moreover, distance between core and systematically varied by inserting rigid phenylene linkers. Femtosecond transient (TA) studies reveal that interfacial charge...
Upon electrochemical oxidation of the precursor complexes [Cp*Ir(H2O)3]SO4 (1) or [(Cp*Ir)2(OH)3]OH (2) (Cp* = pentamethylcyclopentadienyl), a blue layer amorphous iridium oxide containing carbon admixture (BL) is deposited onto anode. The solid-state, material that formed from molecular precursors significantly more active for water-oxidation catalysis than crystalline IrO2 and functions as remarkably robust catalyst, capable catalyzing water without deactivation significant corrosion at...
The domain structure of an amorphous, “blue layer” iridium-oxide water-oxidation catalyst film (BL) electrodeposited from the soluble precursor complex, [Cp*Ir(H2O)3]SO4, was characterized by X-ray pair distribution function (PDF) analysis. results show that experimental PDF can be fit remarkably well using a single Ir5O22 cluster extracted rutile lattice. model includes distortions indicate presence Ir(μ-O)3Ir or distorted Ir(μ-O)2Ir substructures, and hence deviations structure. five Ir...
We have designed two new supramolecular assemblies based on Co(II)-templated coordination of Ru(bpy)32+ (bpy = 2,2′-bipyridyl) analogues as photosensitizers and electron donors to a cobaloxime macrocycle, which are interest proton reduction catalysts. The self-assembled photocatalyst precursors were structurally characterized by Co K-edge X-ray absorption spectroscopy solution-phase scattering. Visible light excitation one the has yielded instantaneous transfer charge separation form...
Photophysical and structural properties of a Cu(I) diimine complex with very strong steric hindrance, [Cu(I)(dppS)2](+) (dppS = 2,9-diphenyl-1,10-phenanthroline disulfonic acid disodium salt), are investigated by optical X-ray transient absorption (OTA XTA) spectroscopy. The bulky phenylsulfonic groups at 2,9 positions phenanthroline ligands force the ground state metal-to-ligand charge-transfer (MLCT) excited to adopt flattened pseudo-tetrahedral coordination geometry in which solvent...
Amorphous thin film oxygen evolving catalysts, OECs, of first-row transition metals show promise to serve as self-assembling photoanode materials in solar-driven, photoelectrochemical `artificial leaf' devices. This report demonstrates the ability use high-energy X-ray scattering and atomic pair distribution function analysis, PDF, resolve structure amorphous metal oxide catalyst films. The analysis is applied here domain differences induced by oxyanion substitution during electrochemical...
PpcA, a tri-heme cytochrome c7 from Geobacter sulfurreducens, was investigated as model for photosensitizer-initiated electron transfer within multi-heme "molecular wire" protein architecture. Escherichia coli expression of PpcA found to be tolerant cysteine site-directed mutagenesis, demonstrated by the successful natively folded proteins bearing mutations at series sites selected vary characteristically with respect three -CXXCH- heme binding domains. The introduced cysteines readily...
Surface binding and interactions of anionic porphyins bound to cationic proteins have been studied for nearly three decades are relevant as models protein surface molecular recognition photoinitiated electron transfer. However, interpretation data in all reports explicitly or implicitly assumed interaction porphyrin with monodisperse solutions. In this report, using small-angle X-ray scattering solution phase samples, we demonstrate that horse heart cytochrome (cyt) c, triheme c7 PpcA from...
Human BST-2/tetherin is a host factor that inhibits the release of enveloped viruses, including HIV-1, HIV-2, and SIV, from cell surface by tethering viruses to membrane. BST-2 has an α-helical ectodomain forms disulfide-linked dimers between two monomers forming coiled coil. The contains three cysteine residues can participate in disulfide bond formation are critical for viral tethering. role disulfides unknown but proposed be maintaining dimer. We explored structure using experimental,...
Cu-Komplex als Photosensibilisator: Die Dynamik eines photoinduzierten Ladungstransfers von einem Kupfer(I)-Diimin-Komplex auf TiO2-Nanopartikel wurde mit einer Kombination aus mehreren zeitauflösenden Spektroskopiemethoden untersucht. Ein effizienter und sehr schneller Elektronentransfer dem MLCT-Singulettzustand resultiert Verzerrung der tetraedrischen Koordinationsumgebung den sperrigen Gruppen an Liganden.
We have used imidazole (Im) and N-methylimidazole (MeIm) as probes of the heme-binding cavity membrane-bound cytochrome (cyt) c1 in detergent-solubilized bc1 complex from Rhodobacter sphaeroides. Imidazole binding to cyt substantially lowers midpoint potential heme fully inhibits activity. Temperature dependences showed that Im (Kd ≈ 330 μm, 25 °C, pH 8) is enthalpically driven (ΔH0 = −56 kJ/mol, ΔS0 −121 J/mol/K), whereas MeIm 30 times weaker 9.3 mm) entropically 47 ΔS0° 197 J/mol/K). The...
The wave-particle duality of light is a controversial topic in modern physics. In this context, work highlights the ability wave-nature on its own to account for conservation energy light-matter interaction. Two simple fundamental properties as wave are involved: period and power P. P depends only amplitude wave's electric magnetic fields (Poynting's vector), can easily be measured with sensor visible infrared lasers. advantage such wave-based approach that it unveils unexpected effects...
The kinetics of imidazole (Im) and N-methylimidazole (MeIm) binding to oxidized cytochrome (cyt) c(1) detergent-solubilized bc(1) complex from Rhodobacter sphaeroides are described. rate formation the cyt c(1)-Im exhibited three separated regions dependence on concentration imidazole: (i) below 8 mM Im, increased with in a parabolic manner; (ii) above 20 mM, leveled off, indicating rate-limiting conformational step lifetime approximately 1 s; (iii) at Im concentrations 100 substantially...
Obscurin, a giant modular cytoskeletal protein, is comprised mostly of tandem immunoglobulin-like (Ig-like) domains. This architecture allows obscurin to connect distal targets within the cell. The linkers connecting Ig domains are usually short (3-4 residues). physical effect arising from these not known; such may lead stiff elongated molecule or, conversely, more compact and dynamic structure. In an effort better understand how affect flexibility, underpinnings this here we study structure...
Abstract To understand design principles for assembling photosynthetic biohybrids that incorporate precisely-controlled sites electron injection into redox enzyme cofactor arrays, we investigated the influence of chirality in assembly photosensitizer ruthenium(II)bis(2,2′-bipyridine)(4-bromomethyl-4′-methyl-2,2′-bipyridine), Ru(bpy) 2 (Br-bpy), when covalently conjugated to cysteine residues introduced by site-directed mutagenesis triheme periplasmic cytochrome A (PpcA) as a model biohybrid...
The pathogenic bacteria Legionella pneumophila is known to cause Legionnaires' Disease, a severe pneumonia that can be fatal immunocompromised individuals and the elderly. Shohdy et al. identified L. vacuole sorting inhibitory protein VipF as putative N-acetyltransferase based on sequence homology. We have characterized basic structural functional properties of confirm this original assignment. Sequence conservation analysis indicates two CoA-binding regions within VipF. Homology modeling...