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Articles 181 - 210 of 690
Full-Text Articles in Chemistry
Synthesis, Structure And Antimicrobial Property Of Green Composites From Cellulose, Wool, Hair And Chicken Feather, Chieu D. Tran, Franja Prosenc, Mladen Franko, Gerald Benzi
Synthesis, Structure And Antimicrobial Property Of Green Composites From Cellulose, Wool, Hair And Chicken Feather, Chieu D. Tran, Franja Prosenc, Mladen Franko, Gerald Benzi
Chemistry Faculty Research and Publications
Novel composites between cellulose (CEL) and keratin (KER) from three different sources (wool, hair and chicken feather) were successfully synthesized in a simple one-step process in which butylmethylimidazolium chloride (BMIm+Cl−), an ionic liquid, was used as the sole solvent. The method is green and recyclable because [BMIm+Cl−] used was recovered for reuse. Spectroscopy (FTIR, XRD) and imaging (SEM) results confirm that CEL and KER remain chemically intact and homogeneously distributed in the composites. KER retains some of its secondary structure in the composites. Interestingly, the minor differences in the structure of KER …
Evidence That Cytochrome B5 Acts As A Redox Donor In Cyp17a1 Mediated Androgen Synthesis, Ruchia Duggal, Yilin Liu, Michael C. Gregory, Ilia G. Denisov, James R. Kincaid, Stephen G. Sligar
Evidence That Cytochrome B5 Acts As A Redox Donor In Cyp17a1 Mediated Androgen Synthesis, Ruchia Duggal, Yilin Liu, Michael C. Gregory, Ilia G. Denisov, James R. Kincaid, Stephen G. Sligar
Chemistry Faculty Research and Publications
Cytochrome P450 17A1 (CYP17A1) is an important drug target for castration resistant prostate cancer. It is a bi-functional enzyme, catalyzing production of glucocorticoid precursors by hydroxylation of pregnene-nucleus, and androgen biosynthesis by a second C--C lyase step, at the expense of glucocorticoid production. Cytochrome b5(cyt b5) is known to be a key regulator of the androgen synthesis reaction in vivo, by a mechanism that is not well understood. Two hypotheses have been proposed for the mechanism by which cyt b5 increases androgen biosynthesis. Cyt b5 could act as an allosteric effector, binding to …
Two's Company, Three's A Crowd: Exciton Localization In Cofacially Arrayed Polyfluorenes, Marat R. Talipov, Maxim Vadimovich Ivanov, Scott A. Reid, Rajendra Rathore
Two's Company, Three's A Crowd: Exciton Localization In Cofacially Arrayed Polyfluorenes, Marat R. Talipov, Maxim Vadimovich Ivanov, Scott A. Reid, Rajendra Rathore
Chemistry Faculty Research and Publications
Understanding the mechanisms of long-range energy transfer through polychromophoric assemblies is critically important in photovoltaics and biochemical systems. Using a set of cofacially arrayed polyfluorenes (Fn), we investigate the mechanism of (singlet) exciton delocalization in π-stacked polychromophoric assemblies. Calculations reveal that effective stabilization of an excimeric state requires an ideal sandwich-like arrangement; yet surprisingly, emission spectroscopy indicates that exciton delocalization is limited to only two fluorene units for all n. Herein, we show that delocalization is determined by the interplay between the energetic gain from delocalization, which quickly saturates beyond two units in larger Fn, …
First Experimental Evidence For The Diverse Requirements Of Excimer Vs Hole Stabilization In Π-Stacked Assemblies, Neil Reilly, Maxim Vadimovich Ivanov, Brandon Uhler, Marat R. Talipov, Rajendra Rathore, Scott A. Reid
First Experimental Evidence For The Diverse Requirements Of Excimer Vs Hole Stabilization In Π-Stacked Assemblies, Neil Reilly, Maxim Vadimovich Ivanov, Brandon Uhler, Marat R. Talipov, Rajendra Rathore, Scott A. Reid
Chemistry Faculty Research and Publications
Exciton formation and charge separation and transport are key dynamical events in a variety of functional polymeric materials and biological systems, including DNA. Beyond the necessary cofacial approach of a pair of aromatic molecules at van der Waals contact, the extent of overlap and necessary geometrical reorganization for optimal stabilization of an excimer vs dimer cation radical remain unresolved. Here, we compare experimentally the dynamics of excimer formation (via emission) and charge stabilization (via threshold ionization) of a novel covalently linked, cofacially stacked fluorene dimer (F2) with the unlinked van der Waals dimer of fluorene, that is, (F)2. …
Efficient Method For Calculations Of Ro-Vibrational States In Triatomic Molecules Near Dissociation Threshold: Application To Ozone, Alexander Teplukhin, Dmitri Babikov
Efficient Method For Calculations Of Ro-Vibrational States In Triatomic Molecules Near Dissociation Threshold: Application To Ozone, Alexander Teplukhin, Dmitri Babikov
Chemistry Faculty Research and Publications
A method for calculations of rotational-vibrational states of triatomic molecules up to dissociation threshold (and scattering resonances above it) is devised, that combines hyper-spherical coordinates, sequential diagonalization-truncation procedure, optimized grid DVR, and complex absorbing potential. Efficiency and accuracy of the method and new code are tested by computing the spectrum of ozone up to dissociation threshold, using two different potential energy surfaces. In both cases good agreement with results of previous studies is obtained for the lower energy states localized in the deep (∼10 000 cm−1) covalent well. Upper part of the bound state spectrum, within 600 cm−1 below dissociation …
Analysis Of Heme Iron Coordination In Dgcr8: The Heme-Binding Component Of The Microprocessor Complex, Hazel M. Girvan, Justin M. Bradley, Myles R. Cheesman, James R. Kincaid, Yilin Liu, Kazimierz Czarnecki, Karl Fisher, David Leys, Stephen E. J. Rigby, Andrew W. Munro
Analysis Of Heme Iron Coordination In Dgcr8: The Heme-Binding Component Of The Microprocessor Complex, Hazel M. Girvan, Justin M. Bradley, Myles R. Cheesman, James R. Kincaid, Yilin Liu, Kazimierz Czarnecki, Karl Fisher, David Leys, Stephen E. J. Rigby, Andrew W. Munro
Chemistry Faculty Research and Publications
DGCR8 is the RNA-binding partner of the nuclease Drosha. Their complex (the “Microprocessor”) is essential for processing of long, primary microRNAs (pri-miRNAs) in the nucleus. Binding of heme to DGCR8 is essential for pri-miRNA processing. On the basis of the split Soret ultraviolet–visible (UV–vis) spectrum of ferric DGCR8, bis-thiolate sulfur (cysteinate, Cys–) heme iron coordination of DGCR8 heme iron was proposed. We have characterized DGCR8 heme ligation using the Δ276 DGCR8 variant and combined electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), electron nuclear double resonance, resonance Raman, and electronic absorption spectroscopy. These studies indicate DGCR8 bis-Cys heme …
Multifunctional Heterocyclic Scaffolds For Hybrid Lewis Acid/Lewis Base Catalysis Of Carbon–Carbon Bond Formation, Dennis Wiedenhoeft, Adam R. Benoit, Yibiao Wu, Jacob D. Porter, Elisia Meyle, Teresa H.W. Yeung, Raechel Huff, Sergey V. Lindeman, Chris Dockendorff
Multifunctional Heterocyclic Scaffolds For Hybrid Lewis Acid/Lewis Base Catalysis Of Carbon–Carbon Bond Formation, Dennis Wiedenhoeft, Adam R. Benoit, Yibiao Wu, Jacob D. Porter, Elisia Meyle, Teresa H.W. Yeung, Raechel Huff, Sergey V. Lindeman, Chris Dockendorff
Chemistry Faculty Research and Publications
No abstract provided.
Supramolecular Assembly Of Metal-Organic Tubes Constructed From The Ditopic Heteroscorpionate Ligand (4-Nh2C6H4)Chpz2 (Pz = Pyrazol-1-Yl) And Silver(I), James R. Gardinier, Jeewantha S. Hewage, Justin Hoffman, Sergey V. Lindeman, Natalia B. Shustova
Supramolecular Assembly Of Metal-Organic Tubes Constructed From The Ditopic Heteroscorpionate Ligand (4-Nh2C6H4)Chpz2 (Pz = Pyrazol-1-Yl) And Silver(I), James R. Gardinier, Jeewantha S. Hewage, Justin Hoffman, Sergey V. Lindeman, Natalia B. Shustova
Chemistry Faculty Research and Publications
The possibility of constructing tubular metal-organic structures with aid of weak hydrogen-bonding interactions between suitably designed metallacycles was explored. For this purpose, the new heteroditopic ligand (4-NH2C6H4)CHpz2 (L1) was prepared in good (75 %) yield by a one-pot procedure starting from commercial 4-acetamidobenzaldehyde. The equimolar reactions between L1 and various silver(I) salts gave the intended 1:1 complexes in which the metallacycles were assembled into tubes. However, the exact nature of the assemblies (including their solvate compositions) varied depending on anion, solvent, and concentration of the original crystallization solution. For the trifluoromethanesulfonate anion, a …
Mononuclear Iron-(Hydro/Semi)Quinonate Complexes Featuring Neutral And Charged Scorpionates: Synthetic Models Of Intermediates In The Hydroquinone Dioxygenase Mechanism, Amanda E. Baum, Sergey V. Lindeman, Adam T. Fiedler
Mononuclear Iron-(Hydro/Semi)Quinonate Complexes Featuring Neutral And Charged Scorpionates: Synthetic Models Of Intermediates In The Hydroquinone Dioxygenase Mechanism, Amanda E. Baum, Sergey V. Lindeman, Adam T. Fiedler
Chemistry Faculty Research and Publications
Neutral and anionic scorpionate ligands have been employed to generate active-site models of hydroquinone dioxygenases (HQDOs). While the nonheme Fe center in nearly all HQDOs is coordinated to one Asp (or Glu) and two His residues, 1,2-gentisate dioxygenase (GDO) is unique in featuring a three His triad instead. A synthetic GDO model was therefore prepared with the neutral tris(4,5-diphenyl-1-methylimidazol-2-yl)phosphine (Ph2TIP) ligand. The gentisate substrate was mimicked with the bidentate ligand 2-(1-methylbenzimidazol-2-yl)hydroquinonate (BIHQ). X-ray diffraction analysis of the resulting complex, [Fe(Ph2TIP)(BIHQ)]OTf (1a), revealed a distorted square-pyramidal geometry. Structural and electrochemical data collected for 1a were compared to …
The Use Of Isomeric Testosterone Dimers To Explore Allosteric Effects In Substrate Binding To Cytochrome P450 Cyp3a4, Ilia G. Denisov, Piotr J. Mak, Yelena V. Grinkova, Dominic Bastien, Gervais Bérubé, Stephen G. Sligar, James R. Kincaid
The Use Of Isomeric Testosterone Dimers To Explore Allosteric Effects In Substrate Binding To Cytochrome P450 Cyp3a4, Ilia G. Denisov, Piotr J. Mak, Yelena V. Grinkova, Dominic Bastien, Gervais Bérubé, Stephen G. Sligar, James R. Kincaid
Chemistry Faculty Research and Publications
Abstract: Cytochrome P450 CYP3A4 is the main drug-metabolizing enzyme in the human liver, being responsible for oxidation of 50% of all pharmaceuticals metabolized by human P450 enzymes. Possessing a large substrate binding pocket, it can simultaneously bind several substrate molecules and often exhibits a complex pattern of drug–drug interactions. In order to better understand structural and functional aspects of binding of multiple substrate molecules to CYP3A4 we used resonance Raman and UV–VIS spectroscopy to document the effects of binding of synthetic testosterone dimers of different configurations, cis-TST2 and trans-TST2. We directly demonstrate that the binding …
Fluorescence Of Supported Phospholipid Bilayers Recorded In A Conventional Horizontal-Beam Spectrofluorometer, Elizaveta A. Kovrigina, Evgeni L. Kovrigin
Fluorescence Of Supported Phospholipid Bilayers Recorded In A Conventional Horizontal-Beam Spectrofluorometer, Elizaveta A. Kovrigina, Evgeni L. Kovrigin
Chemistry Faculty Research and Publications
Supported phospholipid bilayers are a convenient model of cellular membranes in studies of membrane biophysics and protein-lipid interactions. Traditionally, supported lipid bilayers are formed on a flat surface of a glass slide to be observed through fluorescence microscopes. This paper describes a method to enable fluorescence detection from the supported lipid bilayers using standard horizontal-beam spectrofluorometers instead of the microscopes. In the proposed approach, the supported lipid bilayers are formed on the inner optical surfaces of the standard fluorescence microcell. To enable observation of the bilayer absorbed on the cell wall, the microcell is placed in a standard fluorometer cell …
Influence Of Rtil Nanodomains On The Voltammetry And Spectroelectrochemistry Of Fullerene C60 In Benzonitrile/Room Temperature Ionic Liquids Mixtures, Abderrahman Atifi, Michael D. Ryan
Influence Of Rtil Nanodomains On The Voltammetry And Spectroelectrochemistry Of Fullerene C60 In Benzonitrile/Room Temperature Ionic Liquids Mixtures, Abderrahman Atifi, Michael D. Ryan
Chemistry Faculty Research and Publications
The cyclic voltammetry of fullerene C60 was examined in mixed benzonitrile/RTIL solvents in order to probe the effect of nanodomains in the mixed RTIL/benzonitrile solutions and their effect upon the voltammetry. In probing the interactions of the fullerides (up to C603−) with RTILs, BMIm+ (1-butyl-3-methylimidazolium, mostly planar) and tetraalkylammonium (more spherical/flexible) salts were used. In order to investigate these shifts in more detail, the ΔE12° (=E°1–E°2) and ΔE23° (=E°2–E°3) values, which were independent of the reference potential, were used. At higher concentrations of …
Reactivity Of Acyclic (Pentadienyl)Iron(1+) Cations With Phosphonate Stabilized Nucleophiles: Application To The Synthesis Of Oxygenated Metabolites Of Carvone, Do W. Lee, Charles Felix Manful, Jayapal Reddy Gone, Yuzhi Ma, William A. Donaldson
Reactivity Of Acyclic (Pentadienyl)Iron(1+) Cations With Phosphonate Stabilized Nucleophiles: Application To The Synthesis Of Oxygenated Metabolites Of Carvone, Do W. Lee, Charles Felix Manful, Jayapal Reddy Gone, Yuzhi Ma, William A. Donaldson
Chemistry Faculty Research and Publications
The addition of phosphonate stabilized carbon nucleophiles to acyclic (pentadienyl)iron(1+) cations proceeds predominantly at an internal carbon to afford (pentenediyl)iron complexes. Those complexes bearing an electron withdrawing group at the σ-bound carbon (i.e., 13/14) are stable and isolable, while complexes which do not contain an electron withdrawing group at the σ-bound carbon undergo CO insertion, reductive elimination and conjugation of the double bond to afford cyclohexenone products (21/22). Deprotonation of the phosphonate 13/14 or 21 and reaction with paraformaldehyde affords the olefinated products. This methodology was utilized to prepare oxygenated carvone metabolites (±)-25 and (±)-26.
Recent Advances In Development And Applications Of The Mixed Quantum/Classical Theory For Inelastic Scattering, Dmitri Babikov, Alexander Semenov
Recent Advances In Development And Applications Of The Mixed Quantum/Classical Theory For Inelastic Scattering, Dmitri Babikov, Alexander Semenov
Chemistry Faculty Research and Publications
A mixed quantum/classical approach to inelastic scattering (MQCT) is developed in which the relative motion of two collision partners is treated classically, and the rotational and vibrational motion of each molecule is treated quantum mechanically. The cases of molecule + atom and molecule + molecule are considered including diatomics, symmetric-top rotors, and asymmetric-top rotor molecules. Phase information is taken into consideration, permitting calculations of elastic and inelastic, total and differential cross sections for excitation and quenching. The method is numerically efficient and intrinsically parallel. The scaling law of MQCT is favorable, which enables calculations at high collision energies and for …
Inelastic Scattering Of Identical Molecules Within Framework Of The Mixed Quantum/Classical Theory: Application To Rotational Excitations In H2 + H2, Alexander Semenov, Dmitri Babikov
Inelastic Scattering Of Identical Molecules Within Framework Of The Mixed Quantum/Classical Theory: Application To Rotational Excitations In H2 + H2, Alexander Semenov, Dmitri Babikov
Chemistry Faculty Research and Publications
Theoretical foundation is laid out for description of permutation symmetry in the inelastic scattering processes that involve collisions of two identical molecules, within the framework of the mixed quantum/classical theory (MQCT). In this approach, the rotational (and vibrational) states of two molecules are treated quantum-mechanically, whereas their translational motion (responsible for scattering) is treated classically. This theory is applied to H2 + H2 system, and the state-to-state transition cross sections are compared versus those obtained from the full-quantum calculations and experimental results from the literature. Good agreement is found in all cases. It is also found that results of MQCT, …
A Search For Blues Brothers: X-Ray Crystallographic/Spectroscopic Characterization Of The Tetraarylbenzidine Cation Radical As A Product Of Aging Of Solid Magic Blue, Marat R. Talipov, Mohammad M. Hossain, Anitha Boddeda, Khushabu Thakur, Rajendra Rathore
A Search For Blues Brothers: X-Ray Crystallographic/Spectroscopic Characterization Of The Tetraarylbenzidine Cation Radical As A Product Of Aging Of Solid Magic Blue, Marat R. Talipov, Mohammad M. Hossain, Anitha Boddeda, Khushabu Thakur, Rajendra Rathore
Chemistry Faculty Research and Publications
Magic blue (MB+˙ SbCl6− salt), i.e. tris-4-bromophenylamminium cation radical, is a routinely employed one-electron oxidant that slowly decomposes in the solid state upon storage to form so called ‘blues brothers’, which often complicate the quantitative analyses of the oxidation processes. Herein, we disclose the identity of the main ‘blues brother’ as the cation radical and dication of tetrakis-(4-bromophenyl)benzidine (TAB) by a combined DFT and experimental approach, including isolation of TAB+˙ SbCl6− and its X-ray crystallography characterization. The formation of TAB in aged magic blue samples occurs by a Scholl-type …
Hydrogen-Atom Attack On Phenol And Toluene Is Ortho-Directed, Olha Krechkivska, Callan M. Wilcox, Tyler P. Troy, Klaas Nauta, Bun Chan, Rebecca Jacob, Scott A. Reid, Leo Radom, Timothy W. Schmidt, Scott H. Kable
Hydrogen-Atom Attack On Phenol And Toluene Is Ortho-Directed, Olha Krechkivska, Callan M. Wilcox, Tyler P. Troy, Klaas Nauta, Bun Chan, Rebecca Jacob, Scott A. Reid, Leo Radom, Timothy W. Schmidt, Scott H. Kable
Chemistry Faculty Research and Publications
The reaction of H + phenol and H/D + toluene has been studied in a supersonic expansion after electric discharge. The (1 + 1′) resonance-enhanced multiphoton ionization (REMPI) spectra of the reaction products, at m/z = parent + 1, or parent + 2 amu, were measured by scanning the first (resonance) laser. The resulting spectra are highly structured. Ionization energies were measured by scanning the second (ionization) laser, while the first laser was tuned to a specific transition. Theoretical calculations, benchmarked to the well-studied H + benzene → cyclohexadienyl radical reaction, were performed. The spectrum arising from the …
A Flipped Classroom Redesign In General Chemistry, Scott A. Reid
A Flipped Classroom Redesign In General Chemistry, Scott A. Reid
Chemistry Faculty Research and Publications
The flipped classroom continues to attract significant attention in higher education. Building upon our recent parallel controlled study of the flipped classroom in a second-term general chemistry course (J. Chem. Educ., 2016, 93, 13–23), here we report on a redesign of the flipped course aimed at scaling up total enrollment while keeping discussion sizes small (i.e.,students), and maintaining equivalent contact hour load for faculty and workload for students. To that end, the course format featured lecture contact pushed outside of the classroom in the form of video lectures (mean duration 13 minutes) paired with online …
Reactivity Of (3-Methylpentadienyl)Iron(1+) Cation: Late-Stage Introduction Of A (3-Methyl-2z,4-Pentadien-1-Yl) Side Chain, Subhabrata Chaudhury, Shukun Li, William A. Donaldson
Reactivity Of (3-Methylpentadienyl)Iron(1+) Cation: Late-Stage Introduction Of A (3-Methyl-2z,4-Pentadien-1-Yl) Side Chain, Subhabrata Chaudhury, Shukun Li, William A. Donaldson
Chemistry Faculty Research and Publications
The 3-methyl-2Z,4-pentadien-1-yl sidechain is found in various sesquiterpenes and diterpenes. A route for the late stage introduction of this functionality was developed which relies on nucleophilic attack on the (3-methylpentadienyl)iron(1+) cation, followed by oxidative decomplexation. This methodology was applied to the synthesis of the proposed structure of heteroscyphic acid A methyl ester. Realization of this synthesis led to a correction of the proposed structure.
On Stabilization Of Scattering Resonances In Recombination Reaction That Forms Ozone, Mikhail V. Ivanov, Dmitri Babikov
On Stabilization Of Scattering Resonances In Recombination Reaction That Forms Ozone, Mikhail V. Ivanov, Dmitri Babikov
Chemistry Faculty Research and Publications
Calculations of energy transfer in the recombination reaction that forms ozone are carried out within the framework of the mixed quantum/classical theory and using the dimensionally reduced 2D-model of ozone molecule, with bending motion neglected. Recombination rate coefficients are obtained at room temperature for symmetric and asymmetric isotopomers of singly and doubly substituted isotopologues. The processes of resonance formation, spontaneous decay, collisional dissociation, and stabilization by bath gas (Ar) are all characterized and taken into account within the steady-state approximation for kinetics. The focus is on stabilization step, where the mysterious isotopic η-effect was thought to originate from. Our results …
Does Koopmans’ Paradigm For 1-Electron Oxidation Always Hold? Breakdown Of Ip/EOx Relationship For P-Hydroquinone Ethers And The Role Of Methoxy Group Rotation, Marat R. Talipov, Anitha Boddeda, Sergey V. Lindeman, Rajendra Rathore
Does Koopmans’ Paradigm For 1-Electron Oxidation Always Hold? Breakdown Of Ip/EOx Relationship For P-Hydroquinone Ethers And The Role Of Methoxy Group Rotation, Marat R. Talipov, Anitha Boddeda, Sergey V. Lindeman, Rajendra Rathore
Chemistry Faculty Research and Publications
Koopmans’ paradigm states that electron loss occurs from HOMO, thus forming the basis for the observed linear relationships between HOMO/IP, HOMO/Eox, and IP/Eox. In cases where a molecule undergoes dramatic structural reorganization upon 1-electron oxidation, the IP/Eoxrelationship does not hold, and the origin of which is not understood. For example, X-ray crystallography of the neutral and cation radicals of bicyclo[2.2.1]heptane-annulated p-hydroquinone ethers (THE and MHE) showed that they undergo electron-transfer-induced conformational reorganization and show breakdown of the IP/Eox relationship. DFT calculations revealed that Koopmans’ paradigm …
Design And Synthesis Of Oxazoline-Based Scaffolds For Hybrid Lewis Acid/Lewis Base Catalysis Of Carbon–Carbon Bond Formation, Dennis Wiedenhoeft, Adam R. Benoit, Jacob D. Porter, Yibiao Wu, Rajdeep S. Virdi, Alaa Shanaa, Chris Dockendorff
Design And Synthesis Of Oxazoline-Based Scaffolds For Hybrid Lewis Acid/Lewis Base Catalysis Of Carbon–Carbon Bond Formation, Dennis Wiedenhoeft, Adam R. Benoit, Jacob D. Porter, Yibiao Wu, Rajdeep S. Virdi, Alaa Shanaa, Chris Dockendorff
Chemistry Faculty Research and Publications
A new class of hybrid Lewis acid/Lewis base catalysts has been designed and prepared with an initial objective of promoting stereoselective direct aldol reactions. Several scaffolds were synthesized that contain amine moieties capable of enamine catalysis, connected to heterocyclic metal-chelating sections composed of an oxazole–oxazoline or thiazole–oxazoline. Early screening results have identified oxazole–oxazoline-based systems capable of promoting a highly diastereo- and enantioselective direct aldol reaction of propionaldehyde with 4-nitrobenzaldehyde, when combined with Lewis acids such as zinc triflate.
One-Pot Synthesis Of Biocompatible Silver Nanoparticle Composites From Cellulose And Keratin: Characterization And Antimicrobial Activity, Chieu D. Tran, Franja Prosenc, Mladen Franko, Gerald Benzi
One-Pot Synthesis Of Biocompatible Silver Nanoparticle Composites From Cellulose And Keratin: Characterization And Antimicrobial Activity, Chieu D. Tran, Franja Prosenc, Mladen Franko, Gerald Benzi
Chemistry Faculty Research and Publications
A novel, simple method was developed to synthesize biocompatible composites containing 50% cellulose (CEL) and 50% keratin (KER) and silver in the form of either ionic (Ag+) or Ag0 nanoparticles (Ag+NPs or Ag0NPs). In this method, butylmethylimmidazolium chloride ([BMIm+Cl–]), a simple ionic liquid, was used as the sole solvent and silver chloride was added to the [BMIm+Cl–] solution of [CEL+KER] during the dissolution process. The silver in the composites can be maintained as ionic silver (Ag+) or completely converted to metallic silver (Ag …
Accessing Spin-Crossover Behaviour In Iron(Ii) Complexes Of N-Confused Scorpionate Ligands, James R. Gardinier, Alexander Richard Treleven, Kristin J. Meise, Sergey V. Lindeman
Accessing Spin-Crossover Behaviour In Iron(Ii) Complexes Of N-Confused Scorpionate Ligands, James R. Gardinier, Alexander Richard Treleven, Kristin J. Meise, Sergey V. Lindeman
Chemistry Faculty Research and Publications
The first examples of a class of N-confused tris(pyrazolyl)methane ‘scorpionate’ ligands have been prepared. The magnetic properties of their iron(II) tetrafluoroborate complexes are dictated by changing one substituent per ligand rather than three as is typical for normal scorpionate ligands.
A Full-Dimensional Model Of Ozone Forming Reaction: The Absolute Value Of The Recombination Rate Coefficient, Its Pressure And Temperature Dependencies, Alexander Teplukhin, Dmitri Babikov
A Full-Dimensional Model Of Ozone Forming Reaction: The Absolute Value Of The Recombination Rate Coefficient, Its Pressure And Temperature Dependencies, Alexander Teplukhin, Dmitri Babikov
Chemistry Faculty Research and Publications
Rigorous calculations of scattering resonances in ozone are carried out for a broad range of rotational excitations. The accurate potential energy surface of Dawes is adopted, and a new efficient method for calculations of ro–vibrational energies, wave functions and resonance lifetimes is employed (which uses hyper-spherical coordinates, the sequential diagonalization/truncation approach, grid optimization and complex absorbing potential). A detailed analysis is carried out to characterize distributions of resonance energies and lifetimes, their rotational/vibrational content and their positions with respect to the centrifugal barrier. Emphasis is on the contribution of these resonances to the recombination process that forms ozone. It is …
From Wires To Cables: Attempted Synthesis Of 1,3,5-Trifluorenylcyclohexane As A Platform For Molecular Cables, Marat R. Talipov, Sameh H. Abdelwahed, Khushabu Thakur, Scott A. Reid, Rajendra Rathore
From Wires To Cables: Attempted Synthesis Of 1,3,5-Trifluorenylcyclohexane As A Platform For Molecular Cables, Marat R. Talipov, Sameh H. Abdelwahed, Khushabu Thakur, Scott A. Reid, Rajendra Rathore
Chemistry Faculty Research and Publications
Multiple molecular wires braided together in a single assembly, termed as molecular cable, are promising next-generation materials for effective long-range charge transport. As an example of the platform for constructing molecular cables, 1,3,5-trifluorenylcyclohexane (TFC) and its difluorenyl analogues (DFCs) were systematically investigated both experimentally (X-ray crystallography) and theoretically (DFT calculations). Although the syntheses of DFCs were successfully achieved, the synthesis of TFC, which involved a similar intramolecular Friedel–Crafts cyclization as the last step, was unsuccessful. An exhaustive study of the conformational landscape of cyclohexane ring of TFC and DFCs revealed that TFC is …
X-Ray Structure And Properties Of The Ferrous Octaethylporphyrin Nitroxyl Complex, Nagabhushanam Kundakarla, Sergey V. Lindeman, Hafiz Md. Rahman, Michael D. Ryan
X-Ray Structure And Properties Of The Ferrous Octaethylporphyrin Nitroxyl Complex, Nagabhushanam Kundakarla, Sergey V. Lindeman, Hafiz Md. Rahman, Michael D. Ryan
Chemistry Faculty Research and Publications
The preparation and characterization of the iron octaethylporphyrin nitroxyl ion, [Fe(OEP)(NO)−], is reported. The complex was synthesized by the one-electron reduction of Fe(OEP)(NO) using anthracenide as the reducing agent. The compound was isolated as the potassium (2.2.2)cryptand salt. The anion was characterized using X-ray analysis with visible and infrared spectroscopy. The spectral features of the iron nitroxyl complex were consistent with previous literature reports. The important structural changes upon reduction were a significant decrease in the Fe–N–O bond angle from 142° to 127° and an increase in the N–O bond length from that in the starting nitrosyl moiety. …
A Circle Has No End: Role Of Cyclic Topology And Accompanying Structural Reorganization On The Hole Distribution In Cyclic And Linear Poly‑P‑Phenylene Molecular Wires, Marat R. Talipov, Ramesh Jasti, Rajendra Rathore
A Circle Has No End: Role Of Cyclic Topology And Accompanying Structural Reorganization On The Hole Distribution In Cyclic And Linear Poly‑P‑Phenylene Molecular Wires, Marat R. Talipov, Ramesh Jasti, Rajendra Rathore
Chemistry Faculty Research and Publications
π-Conjugated organic oligomers/polymers hold great promise as long-range charge-transfer materials for modern photovoltaic applications. However, a set of criteria for the rational design of functional materials is not yet available, in part because of a lack of understanding of charge distribution in extended π-conjugated systems of different topologies, and concomitant effects on redox and optical properties. Herein we demonstrate the role of cyclic versus linear topology in controlling the redox/optical properties and hole distribution in poly-p-phenylenes (PPs) with the aid of experiment, computation, and our recently developed multistate parabolic model (MPM). It is unequivocally shown that the hole …
Direct Observation Of Photoinduced Charge Separation In Ruthenium Complex/Ni(Oh)2 Nanoparticle Hybrid, Yu Tang, Brian Pattengale, John Ludwig, Abderrahman Atifi, Alexander V. Zinovev, Bin Dong, Qingyu Kong, Xiaobing Zuo, Xiaoyi Zhang, Jier Huang
Direct Observation Of Photoinduced Charge Separation In Ruthenium Complex/Ni(Oh)2 Nanoparticle Hybrid, Yu Tang, Brian Pattengale, John Ludwig, Abderrahman Atifi, Alexander V. Zinovev, Bin Dong, Qingyu Kong, Xiaobing Zuo, Xiaoyi Zhang, Jier Huang
Chemistry Faculty Research and Publications
Ni(OH)2 have emerged as important functional materials for solar fuel conversion because of their potential as cost-effective bifunctional catalysts for both hydrogen and oxygen evolution reactions. However, their roles as photocatalysts in the photoinduced charge separation (CS) reactions remain unexplored. In this paper, we investigate the CS dynamics of a newly designed hybrid catalyst by integrating a Ru complex with Ni(OH)2 nanoparticles (NPs). Using time resolved X-ray absorption spectroscopy (XTA), we directly observed the formation of the reduced Ni metal site (~60 ps), unambiguously demonstrating CS process in the hybrid through ultrafast electron transfer from Ru complex to …
Unveiling The Crucial Intermediates In Androgen Production, Piotr J. Mak, Michael C. Gregory, Ilia G. Denisov, Stephen G. Sligar, James R. Kincaid
Unveiling The Crucial Intermediates In Androgen Production, Piotr J. Mak, Michael C. Gregory, Ilia G. Denisov, Stephen G. Sligar, James R. Kincaid
Chemistry Faculty Research and Publications
Significance: The human enzyme cytochrome P450 17A1 (CYP17A1) catalyzes the critical step in the biosynthesis of the male sex hormones, and, as such, it is a key target for the inhibition of testosterone production that is necessary for the progression of certain cancers. CYP17A1 catalyzes two distinct types of chemical transformations. The first is the hydroxylation of the steroid precursors pregnenolone and progesterone. The second is a different reaction involving carbon–carbon (C-C) bond cleavage, the mechanism of which has been actively debated in the literature. Using a combination of chemical and biophysical methods, we have been able to trap and …