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Articles 301 - 330 of 1105
Full-Text Articles in Chemistry
Di- And Trinuclear Mixed-Valence Copper Amidinate Complexes From Reduction Of Iodine, Andrew C. Lane, Charles L. Barnes, William E. Antholine, Denan Wang, Adam T. Fiedler, Justin R. Walensky
Di- And Trinuclear Mixed-Valence Copper Amidinate Complexes From Reduction Of Iodine, Andrew C. Lane, Charles L. Barnes, William E. Antholine, Denan Wang, Adam T. Fiedler, Justin R. Walensky
Chemistry Faculty Research and Publications
Molecular examples of mixed-valence copper complexes through chemical oxidation are rare but invoked in the mechanism of substrate activation, especially oxygen, in copper-containing enzymes. To examine the cooperative chemistry between two metals in close proximity to each other we began studying the reactivity of a dinuclear Cu(I) amidinate complex. The reaction of [(2,6-Me2C6H3N)2C(H)]2Cu2, 1, with I2 in tetrahydrofuran (THF), CH3CN, and toluene affords three new mixed-valence copper complexes [(2,6-Me2C6H3N)2C(H)]2Cu2(μ2-I3)(THF)2, 2, [(2,6-Me2C6H3N)2C(H)]2Cu2(μ2-I) (NCMe)2, 3, and [(2,6-Me2C6H3N)2C(H)]3Cu3(μ3-I)2, 4, respectively. The first two compounds were characterized by UV-vis and electron paramagnetic resonance spectroscopies, and their molecular structure was determined by X-ray crystallography. Both …
Scope And Mechanistic Analysis For Chemoselective Hydrogenolysis Of Carbonyl Compounds Catalyzed By A Cationic Ruthenium Hydride Complex With A Tunable Phenol Ligand, Nishantha Kumara Kalutharage, Chae S. Yi
Scope And Mechanistic Analysis For Chemoselective Hydrogenolysis Of Carbonyl Compounds Catalyzed By A Cationic Ruthenium Hydride Complex With A Tunable Phenol Ligand, Nishantha Kumara Kalutharage, Chae S. Yi
Chemistry Faculty Research and Publications
A cationic ruthenium hydride complex, [(C6H6)(PCy3)(CO)RuH]+BF4– (1), with a phenol ligand was found to exhibit high catalytic activity for the hydrogenolysis of carbonyl compounds to yield the corresponding aliphatic products. The catalytic method showed exceptionally high chemoselectivity toward the carbonyl reduction over alkene hydrogenation. Kinetic and spectroscopic studies revealed a strong electronic influence of the phenol ligand on the catalyst activity. The Hammett plot of the hydrogenolysis of 4-methoxyacetophenone displayed two opposite linear slopes for the catalytic system 1/p-X-C6H4OH (ρ = …
Generation Of Molecular Complexity From Cyclooctatetraene: Preparation Of Aminobicyclo[5.1.0]Octitols, Mohamed F. El-Mansy, Matthew Flister, Sergey V. Lindeman, Kelsey S. Kalous, Daniel S. Sem, William A. Donaldson
Generation Of Molecular Complexity From Cyclooctatetraene: Preparation Of Aminobicyclo[5.1.0]Octitols, Mohamed F. El-Mansy, Matthew Flister, Sergey V. Lindeman, Kelsey S. Kalous, Daniel S. Sem, William A. Donaldson
Chemistry Faculty Research and Publications
A series of eight stereoisomeric N-(tetrahydroxy bicyclo-[5.1.0]oct-2S*-yl)phthalimides were prepared in one to four steps from N-(bicyclo[5.1.0]octa-3,5-dien-2-yl)phthalimide (±)-7, which is readily available from cyclooctatetraene (62 % yield). The structural assignments of the stereoisomers were established by 1H NMR spectral data as well as X-ray crystal structures for certain members. The outcomes of several epoxydiol hydrolyses, particularly ring contraction and enlargement, are of note. The isomeric phthalimides as well as the free amines did not exhibit β-glucosidase inhibitory activity at a concentration of less than 100 μM.
Crystal Structure Of Cis-2-(2-Carboxycyclopropyl)-Glycine (Ccg-Iii) Monohydrate, Sergey V. Lindeman, Nathaniel J. Wallock, William A. Donaldson
Crystal Structure Of Cis-2-(2-Carboxycyclopropyl)-Glycine (Ccg-Iii) Monohydrate, Sergey V. Lindeman, Nathaniel J. Wallock, William A. Donaldson
Chemistry Faculty Research and Publications
The title compound, C6H9NO4·H2O [systematic name: (αR,1R,2S)-rel-α-amino-2-carboxycyclopropaneacetic acid monohydrate], crystallizes with two organic molecules and two water molecules in the asymmetric unit. The space group is P21 and the organic molecules are enantiomers, thus this is an example of a `false conglomerate' with two molecules of opposite handedness in the asymmetric unit (r.m.s. overlay fit = 0.056 Å for one molecule and its inverted partner). Each molecule exists as a zwitterion, with proton transfer from the amino acid carboxylic acid group to …
Analyzing The Catalytic Role Of Active Site Residues In The Fe-Type Nitrile Hydratase From Comamonas Testosteroni Ni1, Salette Martinez, Rui Wu, Karoline Krzywda, Veronika Opalka, Hei Chan, Dali Liu, Richard C. Holz
Analyzing The Catalytic Role Of Active Site Residues In The Fe-Type Nitrile Hydratase From Comamonas Testosteroni Ni1, Salette Martinez, Rui Wu, Karoline Krzywda, Veronika Opalka, Hei Chan, Dali Liu, Richard C. Holz
Chemistry Faculty Research and Publications
A strictly conserved active site arginine residue (αR157) and two histidine residues (αH80 and αH81) located near the active site of the Fe-type nitrile hydratase from Comamonas testosteroni Ni1 (CtNHase), were mutated. These mutant enzymes were examined for their ability to bind iron and hydrate acrylonitrile. For the αR157A mutant, the residual activity (kcat = 10 ± 2 s−1) accounts for less than 1 % of the wild-type activity (kcat = 1100 ± 30 s−1) while the Km value is nearly unchanged at 205 ± 10 mM. On the …
Towards A Global Model Of Spin-Orbit Coupling In The Halocarbenes, Silver Nyambo, Cyrus Karshenas, Scott A. Reid, Phalgun Lolur, Richard Dawes
Towards A Global Model Of Spin-Orbit Coupling In The Halocarbenes, Silver Nyambo, Cyrus Karshenas, Scott A. Reid, Phalgun Lolur, Richard Dawes
Chemistry Faculty Research and Publications
We report a global analysis of spin-orbit coupling in the mono-halocarbenes, CH(D)X, where X = Cl, Br, and I. These are model systems for examining carbene singlet-triplet energy gaps and spin-orbit coupling. Over the past decade, rich data sets collected using single vibronic level emission spectroscopy and stimulated emission pumping spectroscopy have yielded much information on the ground vibrational level structure and clearly demonstrated the presence of perturbations involving the low-lying triplet state. To model these interactions globally, we compare two approaches. First, we employ a diabatic treatment of the spin-orbit coupling, where the coupling matrix elements are written in …
Discovery Of Bisamide-Heterocycles As Inhibitors Of Scavenger Receptor Bi (Sr-Bi)-Mediated Lipid Uptake, Chris Dockendorff, Patrick W. Faloon, Andrew Germain, Miao Yu, Willmen Youngsaye, Partha P. Nag, Melissa Bennion, Marsha Penman, Thomas J.F. Nieland, Sivaraman Dandapani, José R. Perez, Benito Munoz, Michelle A. Palmer, Stuart L. Schreiber, Monty Krieger
Discovery Of Bisamide-Heterocycles As Inhibitors Of Scavenger Receptor Bi (Sr-Bi)-Mediated Lipid Uptake, Chris Dockendorff, Patrick W. Faloon, Andrew Germain, Miao Yu, Willmen Youngsaye, Partha P. Nag, Melissa Bennion, Marsha Penman, Thomas J.F. Nieland, Sivaraman Dandapani, José R. Perez, Benito Munoz, Michelle A. Palmer, Stuart L. Schreiber, Monty Krieger
Chemistry Faculty Research and Publications
A new series of potent inhibitors of cellular lipid uptake from HDL particles mediated by scavenger receptor, class B, type I (SR-BI) was identified. The series was identified via a high-throughput screen of the National Institutes of Health Molecular Libraries Small Molecule Repository (NIH MLSMR) that measured the transfer of the fluorescent lipid DiI from HDL particles to CHO cells overexpressing SR-BI. The series is characterized by a linear peptidomimetic scaffold with two adjacent amide groups, as well as an aryl-substituted heterocycle. Analogs of the initial hit were rapidly prepared via Ugi 4-component reaction, and select enantiopure compounds were prepared …
Mixed Quantum/Classical Approach For Description Of Molecular Collisions In Astrophysical Environments, Alexander Semenov, Dmitri Babikov
Mixed Quantum/Classical Approach For Description Of Molecular Collisions In Astrophysical Environments, Alexander Semenov, Dmitri Babikov
Chemistry Faculty Research and Publications
An efficient and accurate mixed quantum/classical theory approach for computational treatment of inelastic scattering is extended to describe collision of an atom with a general asymmetric-top rotor polyatomic molecule. Quantum mechanics, employed to describe transitions between the internal states of the molecule, and classical mechanics, employed for description of scattering of the atom, are used in a self-consistent manner. Such calculations for rotational excitation of HCOOCH3 in collisions with He produce accurate results at scattering energies above 15 cm–1, although resonances near threshold, below 5 cm–1, cannot be reproduced. Importantly, the method remains computationally affordable …
Benzo-Fused Lactams From A Diversity-Oriented Synthesis (Dos) Library As Inhibitors Of Scavenger Receptor Bi (Sr-Bi)-Mediated Lipid Uptake, Chris Dockendorff, Patrick W. Faloon, Jun Pu, Miao Yu, Stephen Johnston, Melissa Bennion, Marsha Penman, Thomas J.F. Nieland, Sivaraman Dandapani, José R. Perez, Benito Munoz, Michelle A. Palmer, Stuart L. Schreiber, Monty Krieger
Benzo-Fused Lactams From A Diversity-Oriented Synthesis (Dos) Library As Inhibitors Of Scavenger Receptor Bi (Sr-Bi)-Mediated Lipid Uptake, Chris Dockendorff, Patrick W. Faloon, Jun Pu, Miao Yu, Stephen Johnston, Melissa Bennion, Marsha Penman, Thomas J.F. Nieland, Sivaraman Dandapani, José R. Perez, Benito Munoz, Michelle A. Palmer, Stuart L. Schreiber, Monty Krieger
Chemistry Faculty Research and Publications
We report a new series of 8-membered benzo-fused lactams that inhibit cellular lipid uptake from HDL particles mediated by Scavenger Receptor, Class B, Type I (SR-BI). The series was identified via a high-throughput screen of the National Institutes of Health Molecular Libraries Small Molecule Repository (NIH MLSMR), measuring the transfer of the fluorescent lipid DiI from HDL particles to CHO cells overexpressing SR-BI. The series is part of a previously reported diversity-oriented synthesis (DOS) library prepared via a build-couple-pair approach. Detailed structure–activity relationship (SAR) studies were performed with a selection of the original library, as well as additional analogs prepared …
Visible And Infrared Spectroelectrochemistry Of Zinc And Manganese Porphinones: Metal Vs. Porphyrin Reduction, Florentina Tutunea, Abderrahman Atifi, Michael D. Ryan
Visible And Infrared Spectroelectrochemistry Of Zinc And Manganese Porphinones: Metal Vs. Porphyrin Reduction, Florentina Tutunea, Abderrahman Atifi, Michael D. Ryan
Chemistry Faculty Research and Publications
The visible and infrared spectroelectrochemistry of zinc and manganese porphinones and porphinediones was carried out in THF solutions. The aim of this work was to use FTIR spectroelectrochemistry and DFT calculation to determine whether the reduction was centered predominantly on the metal or the macrocycle. For zinc(II), the first one-electron reduction must occur on the macrocyclic ring because the metal’s d-orbitals are filled (d10). The carbonyl bands on the macrocyclic ring were used to probe the electronic structure because they can be readily observed in the infrared spectra. The results of this study are complementary to previous spectroelectrochemical …
Spectral Characterization Of Cytochromes Cyp11a1 (Aka P450scc) Active Site And Catalytic Intermediates, Qianhong Zhu
Spectral Characterization Of Cytochromes Cyp11a1 (Aka P450scc) Active Site And Catalytic Intermediates, Qianhong Zhu
Dissertations (1934 -)
The Cytochromes P450 are monooxygenases which use dioxygen and endogenous reducing equivalents to generate highly reactive intermediates capable of performing several types of oxidative transformations, most commonly, hydroxylations via the so-called Compound I species. There are two main kinds of mammalian P450s: those functioning in drug metabolism and those that facilitate steroid biosynthesis. Steroidogenic P450s participating in the biosynthesis of steroid hormones are involved in a number of different pathways. CYP11A1, one of the steroidogenic P450s also known as P450scc, is the enzyme that converts cholesterol to pregnenolone through side chain cleavage between carbon 20 and 22. The overall process …
Synthetic And Mechanistic Studies Of Ruthenium Catalyzed C-C, C-N And C-O Bond Activation Reactions, Nishantha Kumara Kalutharage
Synthetic And Mechanistic Studies Of Ruthenium Catalyzed C-C, C-N And C-O Bond Activation Reactions, Nishantha Kumara Kalutharage
Dissertations (1934 -)
Transition metal catalyzed selective C-C, C-N and C-O bond activation reactions are fundamentally important in organometallic chemistry and organic synthesis. Catalytic C-C, C-N and C-O activation are highly valuable for reforming processes of crude oils. Significant research has been devoted to transition metal mediated C-C, C-N and C-O bond cleavage reactions to form new compounds as these processes are expected to provide novel ways to transformation of inexpensive hydrocarbons into more commercially valuable products such as pharmaceuticals, agrochemicals and polymers. A few examples of transition metal catalyzed cross coupling reactions involving C-N bond cleavage have been reported. A well-defined Ru …
Hybrid Computational Toxicology Models For Regulatory Risk Assessment, Prachi Pradeep
Hybrid Computational Toxicology Models For Regulatory Risk Assessment, Prachi Pradeep
Dissertations (1934 -)
Computational toxicology is the development of quantitative structure activity relationship (QSAR) models that relate a quantitative measure of chemical structure to a biological effect. In silico QSAR tools are widely accepted as a faster alternative to time-consuming clinical and animal testing methods for regulatory risk assessment of xenobiotics used in consumer products. However, different QSAR tools often make contrasting predictions for a new xenobiotic and may also vary in their predictive ability for different class of xenobiotics. This makes their use challenging, especially in regulatory applications, where transparency and interpretation of predictions play a crucial role in the development of …
Synthesis And Characterization Of Low Valent Metalloporphyrins, Nagabhushanam Kundakarla
Synthesis And Characterization Of Low Valent Metalloporphyrins, Nagabhushanam Kundakarla
Master's Theses (2009 -)
Metalloporphyrins and metalloporphinones have been seen in a number of enzymes and involved in nitrogen metabolism, photosynthesis, and methanogenesis. The reduction of metalloporphyrins and metalloporphinones are achievable, but the site of reduction in either, the metal center or porphyrin core is still debatable. This prompted us to investigate the position of reduction in order to generate low valent metalloporphyrins and porphinones. The reduced porphyrins were characterized by spectroscopic and X-ray crystallographic methods. Previous work in our laboratory has generated low valent metalloporphyrins and porphinones by electrochemical reduction. In this work cobalt, manganese, and iron low valent metalloporphyrins were generated via …
Toward Electronic Materials Based On Metal Pincer-Type Complexes, Jeewantha Sampath Hewage
Toward Electronic Materials Based On Metal Pincer-Type Complexes, Jeewantha Sampath Hewage
Master's Theses (2009 -)
There is currently a lot of interest in developing electrically conducting or semiconducting metal-organic frameworks (MOF's), highly porous materials constructed by organic ligands bridging metal centers. Typically MOF's are non-conducting and, moreover, they are susceptible to hydrolytic degradation. If hydrolytically stable and electrically conducting MOFs could be realized, then revolutionary new technologies could be envisioned. Currently, organic dicarboxylates are used as bridging organic ligands and one simple strategy to obtain the desired materials is to explore other ligand systems. Pincer ligands are organic compounds that are uninegative and bind metals in a tridentate, meridional fashion with two five-member chelate rings. …
Revisiting The Renner–Teller Effect In The X ̃2Π State Of Ccn: Pulsed Discharge-Supersonic Jet Single Vibronic Level Emission Spectroscopy, Lloyd Godfrey Muzangwa, Scott A. Reid
Revisiting The Renner–Teller Effect In The X ̃2Π State Of Ccn: Pulsed Discharge-Supersonic Jet Single Vibronic Level Emission Spectroscopy, Lloyd Godfrey Muzangwa, Scott A. Reid
Chemistry Faculty Research and Publications
The CCN radical is a prototypical system for study of the Renner–Teller effect in its degenerate X ̃2Π ground state, with a number of experimental and theoretical studies carried out over the past 50 years. Most experimental studies have focused on the low-lying vibrational structure as observed in the high-resolution spectra of hot bands, or in emission. In this work, we have used pulsed-discharge supersonic-jet single vibronic level (SVL) emission spectroscopy from selected levels of the Ã2Δ state to probe the vibronic structure of X ̃2Π up to ∼6000 cm−1 above the …
Parmodulins Inhibit Thrombus Formation Without Inducing Endothelial Injury Caused By Vorapaxar, Omozuanvbo Aisiku, Christian G. Peters, Karen De Ceunynck, Chandra C. Ghosh, James R. Dilks, Susanna F. Fustolo-Gunnink, Mingdong Huang, Chris Dockendorff, Samir M. Parikh, Robert Flaumenhaft
Parmodulins Inhibit Thrombus Formation Without Inducing Endothelial Injury Caused By Vorapaxar, Omozuanvbo Aisiku, Christian G. Peters, Karen De Ceunynck, Chandra C. Ghosh, James R. Dilks, Susanna F. Fustolo-Gunnink, Mingdong Huang, Chris Dockendorff, Samir M. Parikh, Robert Flaumenhaft
Chemistry Faculty Research and Publications
Protease-activated receptor-1 (PAR1) couples the coagulation cascade to platelet activation during myocardial infarction and to endothelial inflammation during sepsis. This receptor demonstrates marked signaling bias. Its activation by thrombin stimulates prothrombotic and proinflammatory signaling, whereas its activation by activated protein C (APC) stimulates cytoprotective and antiinflammatory signaling. A challenge in developing PAR1-targeted therapies is to inhibit detrimental signaling while sparing beneficial pathways. We now characterize a novel class of structurally unrelated small-molecule PAR1 antagonists, termed parmodulins, and compare the activity of these compounds to previously characterized compounds that act at the PAR1 ligand–binding site. We find that parmodulins target …
Synthesis Of 2-Acylphenol And Flavene Derivatives From The Ruthenium-Catalyzed Oxidative C-H Acylation Of Phenols With Aldehydes, Hanbin Lee, Chae S. Yi
Synthesis Of 2-Acylphenol And Flavene Derivatives From The Ruthenium-Catalyzed Oxidative C-H Acylation Of Phenols With Aldehydes, Hanbin Lee, Chae S. Yi
Chemistry Faculty Research and Publications
The cationic ruthenium hydride complex [(C6H6)(PCy3)(CO)RuH]+BF4− has been found to be an effective catalyst for the oxidative C–H coupling reaction of phenols with aldehydes to give 2-acylphenol compounds. The coupling of phenols with α,β-unsaturated aldehydes selectively gives the flavene derivatives. The catalytic method mediates direct oxidative C–H coupling of phenol and aldehyde substrates without using any metal oxidants or forming wasteful byproducts.
Aesthetics In Action: Arts In A Democratic Society: Les Aspin Center For Government, Curtis L. Carter
Aesthetics In Action: Arts In A Democratic Society: Les Aspin Center For Government, Curtis L. Carter
Chemistry Faculty Research and Publications
No abstract provided.
A Cu4S Model For The Nitrous Oxide Reductase Active Sites Supported Only By Nitrogen Ligands, Brittany J. Johnson, William E. Antholine, Sergey V. Lindeman, Neal P. Mankad
A Cu4S Model For The Nitrous Oxide Reductase Active Sites Supported Only By Nitrogen Ligands, Brittany J. Johnson, William E. Antholine, Sergey V. Lindeman, Neal P. Mankad
Chemistry Faculty Research and Publications
To model the (His)7Cu4Sn (n = 1 or 2) active sites of nitrous oxide reductase, the first Cu4(μ4-S) cluster supported only by nitrogen donors has been prepared using amidinate supporting ligands. Structural, magnetic, spectroscopic, and computational characterization is reported. Electrochemical data indicates that the 2-hole model complex can be reduced reversibly to the 1-hole state and irreversibly to the fully reduced state.
Chemoselective Formation Of Unsymmetrically Substituted Ethers From Catalytic Reductive Coupling Of Aldehydes And Ketones With Alcohols In Aqueous Solution, Nishantha Kumara Kalutharage, Chae S. Yi
Chemoselective Formation Of Unsymmetrically Substituted Ethers From Catalytic Reductive Coupling Of Aldehydes And Ketones With Alcohols In Aqueous Solution, Nishantha Kumara Kalutharage, Chae S. Yi
Chemistry Faculty Research and Publications
A well-defined cationic Ru–H complex catalyzes reductive etherification of aldehydes and ketones with alcohols. The catalytic method employs environmentally benign water as the solvent and cheaply available molecular hydrogen as the reducing agent to afford unsymmetrical ethers in a highly chemoselective manner.
Cellulose, Chitosan, And Keratin Composite Materials. Controlled Drug Release, Chieu D. Tran, Tamutsiwa Moven Mututuvari
Cellulose, Chitosan, And Keratin Composite Materials. Controlled Drug Release, Chieu D. Tran, Tamutsiwa Moven Mututuvari
Chemistry Faculty Research and Publications
A method was developed in which cellulose (CEL) and/or chitosan (CS) were added to keratin (KER) to enable [CEL/CS+KER] composites to have better mechanical strength and wider utilization. Butylmethylimmidazolium chloride ([BMIm+Cl–]), an ionic liquid, was used as the sole solvent, and because the [BMIm+Cl–] used was recovered, the method is green and recyclable. Fourier transform infrared spectroscopy results confirm that KER, CS, and CEL remain chemically intact in the composites. Tensile strength results expectedly show that adding CEL or CS into KER substantially increases the mechanical strength of the composites. We found …
Synthetic Studies Of Ambruticin: Preparation Of The C1-C8 Tetrahydropyran And The C17-C24 Dihydropyran Segments, Luping Liu, Julie L. Wondergem, William A. Donaldson
Synthetic Studies Of Ambruticin: Preparation Of The C1-C8 Tetrahydropyran And The C17-C24 Dihydropyran Segments, Luping Liu, Julie L. Wondergem, William A. Donaldson
Chemistry Faculty Research and Publications
The C1-C8 tetrahydropyran and the C17-C24 dihdropyran segments of ambruticin were prepared from L-arabinose in 11 steps, 7.6% overall yield and from (S)-ethyl lactate in 8 steps, 22.2% overall yield respectively.
Bimetallic Complexes Supported By A Redox-Active Ligand With Fused Pincer-Type Coordination Sites, Denan Wang, Sergey V. Lindeman, Adam T. Fiedler
Bimetallic Complexes Supported By A Redox-Active Ligand With Fused Pincer-Type Coordination Sites, Denan Wang, Sergey V. Lindeman, Adam T. Fiedler
Chemistry Faculty Research and Publications
The remarkable chemistry of mononuclear complexes featuring tridentate, meridionally chelating “pincer” ligands has stimulated the development of ligand frameworks containing multiple pincer sites. Here, the coordination chemistry of a novel pentadentate ligand (LN3O2) that provides two closely spaced NNO pincer-type compartments fused together at a central diarylamido unit is described. The trianionic LN3O2 chelate supports homobimetallic structures in which each M(II) ion (M = Co, Cu, Zn) is bound in a meridional fashion by the bridging diarylamido N atom and O,N-donors of the salicyaldimine arms. The metal centers are also coordinated by a mono- or bidentate …
Ultrafast Hole Trapping And Relaxation Dynamics In P-Type Cus Nanodisks, John Ludwig, Li An, Brian Pattengale, Qingyu Kong, Xiaoyi Zhang, Pinxian Xi, Jier Huang
Ultrafast Hole Trapping And Relaxation Dynamics In P-Type Cus Nanodisks, John Ludwig, Li An, Brian Pattengale, Qingyu Kong, Xiaoyi Zhang, Pinxian Xi, Jier Huang
Chemistry Faculty Research and Publications
CuS nanocrystals are potential materials for developing low-cost solar energy conversion devices. Understanding the underlying dynamics of photoinduced carriers in CuS nanocrystals is essential to improve their performance in these devices. In this work, we investigated the photoinduced hole dynamics in CuS nanodisks (NDs) using the combination of transient optical (OTA) and X-ray (XTA) absorption spectroscopy. OTA results show that the broad transient absorption in the visible region is attributed to the photoinduced hot and trapped holes. The hole trapping process occurs on a subpicosecond time scale, followed by carrier recombination (~100 ps). The nature of the hole trapping sites, …
Genetic Algorithm Optimization Of Point Charges In Force Field Development: Challenges And Insights, Maxim Vadimovich Ivanov, Marat R. Talipov, Qadir K. Timerghazin
Genetic Algorithm Optimization Of Point Charges In Force Field Development: Challenges And Insights, Maxim Vadimovich Ivanov, Marat R. Talipov, Qadir K. Timerghazin
Chemistry Faculty Research and Publications
Evolutionary methods, such as genetic algorithms (GAs), provide powerful tools for optimization of the force field parameters, especially in the case of simultaneous fitting of the force field terms against extensive reference data. However, GA fitting of the nonbonded interaction parameters that includes point charges has not been explored in the literature, likely due to numerous difficulties with even a simpler problem of the least-squares fitting of the atomic point charges against a reference molecular electrostatic potential (MEP), which often demonstrates an unusually high variation of the fitted charges on buried atoms. Here, we examine the performance of the GA …
Structural Classification Of Metal Complexes With Three-Coordinate Centres, Timothy L. Davis, Joshua A. Watts, Kenneth J. Brown, Jeewantha S. Hewage, Alexander Richard Treleven, Sergey V. Lindeman, James R. Gardinier
Structural Classification Of Metal Complexes With Three-Coordinate Centres, Timothy L. Davis, Joshua A. Watts, Kenneth J. Brown, Jeewantha S. Hewage, Alexander Richard Treleven, Sergey V. Lindeman, James R. Gardinier
Chemistry Faculty Research and Publications
Attempts to describe the geometry about three-coordinate silver(I) complexes have proven difficult because interatomic angles generally vary wildly and there is no adequate or readily available classification system found in the literature. A search of the Cambridge Structural Database shows that complexes formed between any metal centre and three non-metal donors (18001 examples) usually adopt geometries that are quite different than ideal ‘textbook’ extremes of either trigonal planar (∼4% with α = β = γ = 120 ± 2°), T-shaped (∼0.05% with α = 180 ± 2°, β = γ = 90 ± 2°), or trigonal pyramidal (∼0.3% with α …
Indolinyl-Thiazole Based Inhibitors Of Scavenger Receptor-Bi (Sr-Bi)-Mediated Lipid Transport, Chris Dockendorff, Patrick W. Faloon, Miao Yu, Willmen Youngsaye, Marsha Penman, Thomas J.F. Nieland, Partha P. Nag, Timothy A. Lewis, Jun Pu, Melissa Bennion, Joseph Negri, Conor Paterson, Garrett Lam, Sivaraman Dandapani, José R. Perez, Benito Munoz, Michelle A. Palmer, Stuart L. Schreiber, Monty Krieger
Indolinyl-Thiazole Based Inhibitors Of Scavenger Receptor-Bi (Sr-Bi)-Mediated Lipid Transport, Chris Dockendorff, Patrick W. Faloon, Miao Yu, Willmen Youngsaye, Marsha Penman, Thomas J.F. Nieland, Partha P. Nag, Timothy A. Lewis, Jun Pu, Melissa Bennion, Joseph Negri, Conor Paterson, Garrett Lam, Sivaraman Dandapani, José R. Perez, Benito Munoz, Michelle A. Palmer, Stuart L. Schreiber, Monty Krieger
Chemistry Faculty Research and Publications
A potent class of indolinyl-thiazole based inhibitors of cellular lipid uptake mediated by scavenger receptor, class B, type I (SR-BI) was identified via a high-throughput screen of the National Institutes of Health Molecular Libraries Small Molecule Repository (NIH MLSMR) in an assay measuring the uptake of the fluorescent lipid DiI from HDL particles. This class of compounds is represented by ML278 (17–11), a potent (average IC50 = 6 nM) and reversible inhibitor of lipid uptake via SR-BI. ML278 is a plasma-stable, noncytotoxic probe that exhibits moderate metabolic stability, thus displaying improved properties for in vitro …
Electrostatic Point Charge Fitting As An Inverse Problem: Revealing The Underlying Ill-Conditioning, Maxim Vadimovich Ivanov, Marat R. Talipov, Qadir K. Timerghazin
Electrostatic Point Charge Fitting As An Inverse Problem: Revealing The Underlying Ill-Conditioning, Maxim Vadimovich Ivanov, Marat R. Talipov, Qadir K. Timerghazin
Chemistry Faculty Research and Publications
Atom-centered point charge (PC) model of the molecular electrostatics-a major workhorse of the atomistic biomolecular simulations-is usually parameterized by least-squares (LS) fitting of the point charge values to a reference electrostatic potential, a procedure that suffers from numerical instabilities due to the ill-conditioned nature of the LS problem. To reveal the origins of this ill-conditioning, we start with a general treatment of the point charge fitting problem as an inverse problem and construct an analytical model with the point charges spherically arranged according to Lebedev quadrature which is naturally suited for the inverse electrostatic problem. This analytical model is contrasted …
Mono-N-Acyl-2,6-Diaminopimelic Acid Derivatives: Analysis By Electromigration And Spectroscopic Methods And Examination Of Enzyme Inhibitory Activity, Jan Hlaváček, Miloslava Vítovcová, Petra Sázelová, Jan Pícha, Václav Vaněk, Miloš Buděšínský, Jiří Jiráček, Danuta M. Gillner, Richard C. Holz, Ivan Mikšík, Václav Kašička
Mono-N-Acyl-2,6-Diaminopimelic Acid Derivatives: Analysis By Electromigration And Spectroscopic Methods And Examination Of Enzyme Inhibitory Activity, Jan Hlaváček, Miloslava Vítovcová, Petra Sázelová, Jan Pícha, Václav Vaněk, Miloš Buděšínský, Jiří Jiráček, Danuta M. Gillner, Richard C. Holz, Ivan Mikšík, Václav Kašička
Chemistry Faculty Research and Publications
Thirteen mono-N-acyl derivatives of 2,6-diaminopimelic acid (DAP)—new potential inhibitors of the dapE-encoded N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE; EC 3.5.1.18)—were analyzed and characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies and two capillary electromigration methods: capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC). Structural features of DAP derivatives were characterized by IR and NMR spectroscopies, whereas CZE and MEKC were applied to evaluate their purity and to investigate their electromigration properties. Effective electrophoretic mobilities of these compounds were determined by CZE in acidic and alkaline background electrolytes (BGEs) and by MEKC in acidic and alkaline BGEs …