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Articles 121 - 150 of 1105
Full-Text Articles in Chemistry
Tuning Internal Strain In Metal–Organic Frameworks Via Vapor Phase Infiltration For Co2 Reduction, Fan Yang, Wenhui Hu, Chongqing Yang, Margaret Patrick, Andrew L. Cooksy, Jian Zhang, Jeffery A. Aguiar, Chengcheng Fang, Yinghua Zhou, Ying Shirley Meng, Jier Huang, Jing Gu
Tuning Internal Strain In Metal–Organic Frameworks Via Vapor Phase Infiltration For Co2 Reduction, Fan Yang, Wenhui Hu, Chongqing Yang, Margaret Patrick, Andrew L. Cooksy, Jian Zhang, Jeffery A. Aguiar, Chengcheng Fang, Yinghua Zhou, Ying Shirley Meng, Jier Huang, Jing Gu
Chemistry Faculty Research and Publications
A gas-phase approach to form Zn coordination sites on metal–organic frameworks (MOFs) by vapor-phase infiltration (VPI) was developed. Compared to Zn sites synthesized by the solution-phase method, VPI samples revealed approximately 2.8 % internal strain. Faradaic efficiency towards conversion of CO2 to CO was enhanced by up to a factor of four, and the initial potential was positively shifted by 200–300 mV. Using element-specific X-ray absorption spectroscopy, the local coordination environment of the Zn center was determined to have square-pyramidal geometry with four Zn−N bonds in the equatorial plane and one Zn-OH2 bond in the axial plane. The …
Infrared Spectroelectrochemistry Of Iron-Nitrosyl Triarylcorroles. Implications For Ligand Noninnocence, Md. Hafizur Rahman, Michael D. Ryan, Hugo Vazquez-Lima, Abraham Alemayehu, Abhik Ghosh
Infrared Spectroelectrochemistry Of Iron-Nitrosyl Triarylcorroles. Implications For Ligand Noninnocence, Md. Hafizur Rahman, Michael D. Ryan, Hugo Vazquez-Lima, Abraham Alemayehu, Abhik Ghosh
Chemistry Faculty Research and Publications
Recent DFT calculations have suggested that iron nitrosyl triarylcorrole complexes have substantial {FeNO}7–corrole•2– character. With this formulation, reduction of Fe(C)(NO) complexes, where C = triarylcorrole, should be centered on the corrole macrocycle rather than on the {FeNO}7 moiety. To verify this proposition, visible and infrared spectroelectrochemical studies of Fe(C)(NO) were carried out and the results were interpreted using DFT (B3LYP/STO-TZP) calculations. The first reduction of Fe(C)(NO) led to significant changes in the Soret and Q-band regions of the visible spectrum as well as to a significant downshift in the νNO and changes in the corrole …
Unraveling The Intermediate Species Of Co3O4 Hollow Spheres For Co2 Photoreduction By In Situ X-Ray Absorption Spectroscopy, Peilei He, Sizhou Yang, Wenhui Hu, Sungsik Lee, Jier Huang
Unraveling The Intermediate Species Of Co3O4 Hollow Spheres For Co2 Photoreduction By In Situ X-Ray Absorption Spectroscopy, Peilei He, Sizhou Yang, Wenhui Hu, Sungsik Lee, Jier Huang
Chemistry Faculty Research and Publications
Nanostructured hollow materials have emerged as a promising class of materials for energy conversion and storage. In this work, we report a Co3O4 hollow sphere nanostructure that can serve as a CO2 reduction catalyst to form CO with high selectivity upon visible-light illumination in the presence of a [Ru(bpy)3]2+ molecular photosensitizer. Using in situ X-ray absorption spectroscopy, we not only showed that the Co center in the Co3O4 hollow sphere is the active site for CO2 reduction but also identified a key intermediate species, that is, a reduced Co …
Adiabatic Trajectory Approximation Within The Framework Of Mixed Quantum/Classical Theory, Bikramaditya Mandal, Alexander Semenov, Dmitri Babikov
Adiabatic Trajectory Approximation Within The Framework Of Mixed Quantum/Classical Theory, Bikramaditya Mandal, Alexander Semenov, Dmitri Babikov
Chemistry Faculty Research and Publications
A hierarchy of approximate methods is proposed for solving the equations of motion within a framework of the mixed quantum/classical theory (MQCT) of inelastic molecular collisions. Of particular interest is a limiting case: the method in which the classical-like equations of motion for the translational degrees of freedom (scattering) are decoupled from the quantum-like equations for time evolution of the internal molecular states (rotational and vibrational). In practice, trajectories are pre-computed during the first step of calculations with driving forces determined solely by the potential energy surface of the entrance channel, which is an adiabatic trajectory approximation. Quantum state-to-state transition …
Route Exploration And Synthesis Of The Reported Pyridone-Based Pdi Inhibitor Stk076545, Eric Greve, Sergey V. Lindeman, Christina Scartelli, Lin Lin, Robert Flaumenhaft, Chris Dockendorff
Route Exploration And Synthesis Of The Reported Pyridone-Based Pdi Inhibitor Stk076545, Eric Greve, Sergey V. Lindeman, Christina Scartelli, Lin Lin, Robert Flaumenhaft, Chris Dockendorff
Chemistry Faculty Research and Publications
The enzyme protein disulfide isomerase (PDI) is essential for the correct folding of proteins and the activation of certain cell surface receptors, and is a promising target for the treatment of cancer and thrombotic conditions. A previous high-throughput screen identified the commercial compound STK076545 as a promising PDI inhibitor. To confirm its activity and support further biological studies, a resynthesis was pursued of the reported β-keto-amide with an N-alkylated pyridone at the α-position. Numerous conventional approaches were complicated by undesired fragmentations or rearrangements. However, a successful 5-step synthetic route was achieved using an aldol reaction with an α-pyridone allyl …
Nonheme Iron–Thiolate Complexes As Structural Models Of Sulfoxide Synthase Active Sites, Danushka M. Ekanayake, Anne A. Fischer, Maya E. Elwood, Alexandra M. Guzek, Sergey V. Lindeman, Cordina V. Popescu, Adam T. Fiedler
Nonheme Iron–Thiolate Complexes As Structural Models Of Sulfoxide Synthase Active Sites, Danushka M. Ekanayake, Anne A. Fischer, Maya E. Elwood, Alexandra M. Guzek, Sergey V. Lindeman, Cordina V. Popescu, Adam T. Fiedler
Chemistry Faculty Research and Publications
Two mononuclear iron(II)–thiolate complexes have been prepared that represent structural models of the nonheme iron enzymes EgtB and OvoA, which catalyze the O2-dependent formation of carbon–sulfur bonds in the biosynthesis of thiohistidine compounds. The series of Fe(II) complexes reported here feature tripodal N4 chelates (LA and LB) that contain both pyridyl and imidazolyl donors (LA = (1H-imidazol-4-yl)-N,N-bis((pyridin-2-yl)methyl)methanamine; LB = N,N-bis((1-methylimidazol-2-yl)methyl)-2-pyridylmethylamine). Further coordination with monodentate aromatic or aliphatic thiolate ligands yielded the five-coordinate, high-spin Fe(II) complexes [FeII(LA)(SMes)]BPh …
Voltammetry And Spectroelectrochemistry Of Tcnq In Acetonitrile/Rtil Mixtures, Abderrahman Atifi, Michael D. Ryan
Voltammetry And Spectroelectrochemistry Of Tcnq In Acetonitrile/Rtil Mixtures, Abderrahman Atifi, Michael D. Ryan
Chemistry Faculty Research and Publications
Understanding the solvation and ion-pairing interactions of anionic substrates in room-temperature ionic liquids (RTIL) is key for the electrochemical applications of these new classes of solvents. In this work, cyclic voltammetry and visible and infrared spectroelectrochemistry of tetracyanoquinodimethane (TCNQ) was examined in molecular (acetonitrile) and RTIL solvents, as well as mixtures of these solvents. The overall results were consistent with the formation of RTIL/acetonitrile nanodomains. The voltammetry indicated that the first electrogenerated product, TCNQ−, was not incorporated into the RTIL nanodomain, while the second electrogenerated product, TCNQ2−, was strongly attracted to the RTIL nanodomain. The visible …
Enhanced Light Harvesting Ability In Zeolitic Imidazolate Frameworks Through Energy Transfer From Cds Nanowires, Yixuan Zhou, Wenhui Hu, Sizhuo Yang, Jier Huang
Enhanced Light Harvesting Ability In Zeolitic Imidazolate Frameworks Through Energy Transfer From Cds Nanowires, Yixuan Zhou, Wenhui Hu, Sizhuo Yang, Jier Huang
Chemistry Faculty Research and Publications
Zeolitic imidazolate frameworks (ZIFs) represent a novel class of porous crystalline materials that have demonstrated potential as light harvesting materials for solar energy conversion. In order to facilitate their application in solar energy conversion, it is necessary to expand their absorption further into the realm of the solar spectrum. In this work, we report the incorporation of semiconductor cadmium sulfide nanowires (CdS NWs) into ZIF-67 (CdS@ZIF-67), where a broader region of the solar spectrum can be absorbed by CdS NWs and relayed to ZIF-67 through an energy transfer (EnT) process. Using steady-state emission and time resolved emission and absorption spectroscopy, …
Dynamic Evolution And Reversibility Of Single-Atom Ni(Ii) Active Site In 1t-Mos2 Electrocatalysts For Hydrogen Evolution, Brian Pattengale, Yichao Huang, Xingxu Yan, Sizhou Yang, Sabrina Younan, Wenhui Hu, Zhida Li, Sungsik Lee, Xiaoping Pan, Jing Gu, Jier Huang
Dynamic Evolution And Reversibility Of Single-Atom Ni(Ii) Active Site In 1t-Mos2 Electrocatalysts For Hydrogen Evolution, Brian Pattengale, Yichao Huang, Xingxu Yan, Sizhou Yang, Sabrina Younan, Wenhui Hu, Zhida Li, Sungsik Lee, Xiaoping Pan, Jing Gu, Jier Huang
Chemistry Faculty Research and Publications
1T-MoS2 and single-atom modified analogues represent a highly promising class of low-cost catalysts for hydrogen evolution reaction (HER). However, the role of single atoms, either as active species or promoters, remains vague despite its essentiality toward more efficient HER. In this work, we report the unambiguous identification of Ni single atom as key active sites in the basal plane of 1T-MoS2 (Ni@1T-MoS2) that result in efficient HER performance. The intermediate structure of this Ni active site under catalytic conditions was captured by in situ X-ray absorption spectroscopy, where a reversible metallic Ni species (Ni0) …
Influence Of The Coriolis Effect On The Properties Of Scattering Resonances In Symmetric And Asymmetric Isotopomers Of Ozone, Igor Gayday, Elizaveta Grushnikova, Dmitri Babikov
Influence Of The Coriolis Effect On The Properties Of Scattering Resonances In Symmetric And Asymmetric Isotopomers Of Ozone, Igor Gayday, Elizaveta Grushnikova, Dmitri Babikov
Chemistry Faculty Research and Publications
Scattering resonances above dissociation threshold are computed for four isotopically substituted ozone species: 16O18O16O, 16O16O18O, 18O16O18O and 16O18O18O, using a variational method with accurate treatment of the rotation–vibration coupling terms (Coriolis effect) for all values of the total angular momentum J from 0 to 4. To make these calculations numerically affordable, a new approach was developed which employs one vibrational basis set optimized for a typical rotational excitation (J,Λ), to run coupled rotation–vibration calculations at several …
Composition Effect On The Carrier Dynamics And Catalytic Performance Of Cuins2/Zns Quantum Dots For Light Driven Hydrogen Generation, Wenhui Hu, Sizhuo Yang, Jier Huang
Composition Effect On The Carrier Dynamics And Catalytic Performance Of Cuins2/Zns Quantum Dots For Light Driven Hydrogen Generation, Wenhui Hu, Sizhuo Yang, Jier Huang
Chemistry Faculty Research and Publications
Water soluble CuInS2/ZnS quantum dots (QDs) represent one of the most promising single component photocatalysts for the hydrogen evolution reaction (HER). In this work, we report the effect of cation composition in CuInS2/ZnS QDs on the carrier relaxation and charge separation dynamics as well as their photocatalytic performance for the HER. With decreasing Cu to In ratio (increasing Cu deficiency), we observed slightly faster electron trapping and carrier recombination but significantly improved photocatalytic activity for the HER. This can be attributed to the enhanced electron transfer (ET) from the sacrificial donor to CuInS2/ZnS QDs …
Spectroscopic And Computational Comparisons Of Thiolate-Ligated Ferric Nonheme Complexes To Cysteine Dioxygenase: Second-Sphere Effects On Substrate (Analogue) Positioning, Anne A. Fischer, Joshua R. Miller, Richard J. Jodts, Danushka M. Ekanayake, Sergey V. Lindeman, Thomas C. Brunold, Adam T. Fiedler
Spectroscopic And Computational Comparisons Of Thiolate-Ligated Ferric Nonheme Complexes To Cysteine Dioxygenase: Second-Sphere Effects On Substrate (Analogue) Positioning, Anne A. Fischer, Joshua R. Miller, Richard J. Jodts, Danushka M. Ekanayake, Sergey V. Lindeman, Thomas C. Brunold, Adam T. Fiedler
Chemistry Faculty Research and Publications
Parallel spectroscopic and computational studies of iron(III) cysteine dioxygenase (CDO) and synthetic models are presented. The synthetic complexes utilize the ligand tris(4,5-diphenyl-1-methylimidazol-2-yl)phosphine (Ph2TIP), which mimics the facial three-histidine triad of CDO and other thiol dioxygenases. In addition to the previously reported [FeII(CysOEt)(Ph2TIP)]BPh4 (1; CysOEt is the ethyl ester of anionic l-cysteine), the formation and crystallographic characterization of [FeII(2-MTS)(Ph2TIP)]BPh4 (2) is reported, where the methyl 2-thiosalicylate anion (2-MTS) resembles the substrate of 3-mercaptopropionate dioxygenase (MDO). One-electron chemical oxidation of 1 and 2 yields ferric species …
Hybrid Catalysis For The Direct Addition Of Unactivated Aldehydes And Ketones To Alkenes And Alkynes, Jacob Porter
Hybrid Catalysis For The Direct Addition Of Unactivated Aldehydes And Ketones To Alkenes And Alkynes, Jacob Porter
Dissertations (1934 -)
Reactions for the alpha functionalization of carbonyl compounds are important for the synthesis of complex organic materials such as pharmaceuticals, agrochemicals, and natural products. Current methodology used to perform these reactions is inefficient in that pre-activated coupling partners or sensitive catalysts are usually required. Described herein is the study and development of bifunctional and dual catalytic systems for carbon-carbon bond formation via the direct addition of unactivated carbonyl compounds to unactivated alkenes/alkynes. A dual catalyst system is one which utilizes two distinct catalysts to simultaneously activate separate reactants, and in a bifunctional catalyst the two catalytic components are present separately …
Proton Transfer Versus Hydrogen Bonding In A Reduced Iron Porphyrin Nitrosyl Complex, Md. Hafizur Rahman, Yilin Liu, Michael D. Ryan
Proton Transfer Versus Hydrogen Bonding In A Reduced Iron Porphyrin Nitrosyl Complex, Md. Hafizur Rahman, Yilin Liu, Michael D. Ryan
Chemistry Faculty Research and Publications
The 1H NMR spectra of Fe(OEP)(HNO), which was formed from Fe(OEP)(NO)− in the presence of 3,5-dichlorophenol, were studied as a function of temperature. The chemical shift of the HNO proton showed a unique behavior which could be explained based on the equilibrium between the protonated complex, Fe(OEP)(HNO), and the hydrogen-bonded complex, Fe(OEP)(NO)−···HOPh. This equilibrium was consistent with UV/visible spectroscopy and the voltammetric data. UV/visible stopped-flow experiments showed that the hydrogen-bonded complex, which was formed when weak acids such as phenol were added, and the Fe(OEP)(HNO) complex were quite similar. In addition to the HNO proton resonance, …
Empirical Mappings Of The Frequency Response Of An Electron Ratchet To The Characteristics Of The Polymer Transport Layer, Mohamad S. Kodaimati, Ofer Kedem, George C. Schatz, Emily A. Weiss
Empirical Mappings Of The Frequency Response Of An Electron Ratchet To The Characteristics Of The Polymer Transport Layer, Mohamad S. Kodaimati, Ofer Kedem, George C. Schatz, Emily A. Weiss
Chemistry Faculty Research and Publications
Flashing electron ratchets oscillate a periodic asymmetric potential to rectify nondirectional forces and thereby produce directional transport of electrons with zero source-drain bias. The relationship between the oscillation frequency of the potential and the ratchet (short-circuit) current reflects microscopic mechanisms of charge transport within the device. This paper describes experimental mappings of the “optimal frequency(ies)” of the ratchet fpeak—the oscillation frequencies that produce the largest ratchet current—to the carrier concentration, nh, and to the linear field effect transistor mobility, μh, for a poly(3-hexylthiophene-2,5-diyl) (P3HT) transport layer. Measurements on multiple devices, multiple P3HT films per …
Evaluation Of Α-Hydroxycinnamic Acids As Pyruvate Carboxylase Inhibitors, Daniel J. Burkett, Brittney N. Wyatt, Mallory Mews, Anson Bautista, Ryan Engel, Chris Dockendorff, William A. Donaldson, Martin St. Maurice
Evaluation Of Α-Hydroxycinnamic Acids As Pyruvate Carboxylase Inhibitors, Daniel J. Burkett, Brittney N. Wyatt, Mallory Mews, Anson Bautista, Ryan Engel, Chris Dockendorff, William A. Donaldson, Martin St. Maurice
Chemistry Faculty Research and Publications
Through a structure-based drug design project (SBDD), potent small molecule inhibitors of pyruvate carboxylase (PC) have been discovered. A series of α-keto acids (7) and α-hydroxycinnamic acids (8) were prepared and evaluated for inhibition of PC in two assays. The two most potent inhibitors were 3,3′-(1,4-phenylene)bis[2-hydroxy-2-propenoic acid] (8u) and 2-hydroxy-3-(quinoline-2-yl)propenoic acid (8v) with IC50 values of 3.0 ± 1.0 μM and 4.3 ± 1.5 μM respectively. Compound 8v is a competitive inhibitor with respect to pyruvate (Ki = 0.74 μM) and a mixed-type inhibitor with respect to ATP, indicating …
The Parmodulin Nrd-21 Is An Allosteric Inhibitor Of Par1 Gq Signaling With Improved Anti-Inflammatory Activity And Stability, Disha M. Gandhi, Ricardo Rosas Jr., Eric Greve, Kaitlin Kentala, N'Guessan D.-R, Diby, Vladyslava A. Snyder, Allison Stephans, Teresa H.W. Yeung, Saravanan Subramaniam, Elliot Dimilo, Khia E. Kurtenbach, Leggy A. Arnold, Hartmut Weiler, Chris Dockendorff
The Parmodulin Nrd-21 Is An Allosteric Inhibitor Of Par1 Gq Signaling With Improved Anti-Inflammatory Activity And Stability, Disha M. Gandhi, Ricardo Rosas Jr., Eric Greve, Kaitlin Kentala, N'Guessan D.-R, Diby, Vladyslava A. Snyder, Allison Stephans, Teresa H.W. Yeung, Saravanan Subramaniam, Elliot Dimilo, Khia E. Kurtenbach, Leggy A. Arnold, Hartmut Weiler, Chris Dockendorff
Chemistry Faculty Research and Publications
Novel analogs of the allosteric, biased PAR1 ligand ML161 (parmodulin 2, PM2) were prepared in order to identify potential anti-thrombotic and anti-inflammatory compounds of the parmodulin class with improved properties. Investigations of structure-activity relationships of the western portion of the 1,3-diaminobenzene scaffold were performed using an intracellular calcium mobilization assay with endothelial cells, and several heterocycles were identified that inhibited PAR1 at sub-micromolar concentrations. The oxazole NRD-21 was profiled in additional detail, and it was confirmed to act as a selective, reversible, negative allosteric modulator of PAR1. In addition to inhibiting human platelet aggregation, it showed superior anti-inflammatory activity to …
Β-Fluorofentanyls Are Ph-Sensitive Mu Opioid Receptor Agonists, Ricardo Rosas Jr., Xi-Ping Huang, Bryan L. Roth, Chris Dockendorff
Β-Fluorofentanyls Are Ph-Sensitive Mu Opioid Receptor Agonists, Ricardo Rosas Jr., Xi-Ping Huang, Bryan L. Roth, Chris Dockendorff
Chemistry Faculty Research and Publications
The concept recently postulated by Stein and co-workers (Science2017, 355, 966) that mu opioid receptor (MOR) agonists possessing amines with attenuated basicity show pH-dependent activity and can selectively act at damaged, low pH tissues has been additionally supported by in vitro studies reported here. We synthesized and tested analogs of fentanyl possessing one or two fluorine atoms at the beta position of the phenethylamine side chain, with additional fluorines optionally added to the benzene ring of the side chain. These compounds were synthesized in 1 to 3 steps from commercial building blocks. The novel bis-fluorinated analog …
Improving Performance Of The Smd Solvation Model: Bondi Radii Improve Predicted Aqueous Solvation Free Energies Of Ions And PkA Values Of Thiols, Saber Mirzaei, Maxim Vadimovich Ivanov, Qadir K. Timerghazin
Improving Performance Of The Smd Solvation Model: Bondi Radii Improve Predicted Aqueous Solvation Free Energies Of Ions And PkA Values Of Thiols, Saber Mirzaei, Maxim Vadimovich Ivanov, Qadir K. Timerghazin
Chemistry Faculty Research and Publications
Calculation of the solvation free energy of ionic molecules is the principal source of errors in the quantum chemical evaluation of pKa values using implicit polarizable continuum solvent models. One of the important parameters affecting the performance of these models is the choice of atomic radii. Here, we assess the performance of the solvation model based on density (SMD) implicit solvation model employing SMD default radii (SMD) and Bondi radii (SMD-B), a set of empirical atomic radii developed based on the crystallographic data. For a set of 112 ions (60 anions and 52 cations), the SMD-B model showed …
Calculation Of Molecular Vibrational Spectra On A Quantum Annealer, Alexander Teplukhin, Brian K. Kendrick, Dmitri Babikov
Calculation Of Molecular Vibrational Spectra On A Quantum Annealer, Alexander Teplukhin, Brian K. Kendrick, Dmitri Babikov
Chemistry Faculty Research and Publications
Until recently molecular energy calculations using quantum computing hardware have been limited to gate-based quantum computers. In this paper, a new methodology is presented to calculate the vibrational spectrum of a molecule on a quantum annealer. The key idea of the method is a mapping of the ground state variational problem onto an Ising or quadratic unconstrained binary optimization (QUBO) problem by expressing the expansion coefficients using spins or qubits. The algorithm is general and represents a new revolutionary approach for solving the real symmetric eigenvalue problem on a quantum annealer. The method is applied to two chemically important molecules: …
Selective Excited-State Dynamics In A Unique Set Of Rationally Designed Ni Porphyrins, Brian Pattengale, Qiuhua Liu, Wenhui Hu, Sizhuo Yang, Peilei He, Sir Lawrence Tender, Yingqi Wang, Xiaoyi Zhang, Zaichun Zhou, Jian Zhang, Jier Huang
Selective Excited-State Dynamics In A Unique Set Of Rationally Designed Ni Porphyrins, Brian Pattengale, Qiuhua Liu, Wenhui Hu, Sizhuo Yang, Peilei He, Sir Lawrence Tender, Yingqi Wang, Xiaoyi Zhang, Zaichun Zhou, Jian Zhang, Jier Huang
Chemistry Faculty Research and Publications
In this work, we report the design and photophysical properties of a unique class of Ni porphyrins, in which the tert-butyl benzene substituents at the meso positions of the macrocycle were tethered by ethers with alkyl linkers. This not only results in the permanently locked ruf distortion of the macrocycle but also enables the engineering of the degree of distortion through varying the length of alkyl linkers, which addressed the complication of uncertainty in the specific structural distortions that has long plagued the porphyrin photophysical community. Using advanced time-resolved optical and X-ray absorption spectroscopy, we observed tunability in the …
Structure And Mechanisms Of Metalloenzymes For Incorporation Of Water Across Cn And C-Cl Bonds, Xinhang Yang
Structure And Mechanisms Of Metalloenzymes For Incorporation Of Water Across Cn And C-Cl Bonds, Xinhang Yang
Dissertations (1934 -)
Metalloenzymes are widely involved in water incorporation across CN and C-Cl bonds.1 In this research, the structure and mechanisms of two novel metalloenzymes that incorporate water across CN and C-Cl bonds were examined by biophysical approaches, computational modeling, and crystallographic methods.In the research of water incorporation across CN bonds, a novel eukaryotic nitrile hydratase (NHase, EC 4.2.1.84) from Monosiga brevicollis (MbNHase) was characterized, and the functional role of a (His)17 section and an insert region in the MbNHase, were examined by gene modifications. Each of these MbNHase enzymes provided an 22 heterotetramer, identical to that observed for prokaryotic NHases …
Investigation Of The Active Site Maturation And Catalytic Mechanism Of Nitrile Hydratases (Nhase, E.C.4.2.1.84), Irene Anyango Ogutu
Investigation Of The Active Site Maturation And Catalytic Mechanism Of Nitrile Hydratases (Nhase, E.C.4.2.1.84), Irene Anyango Ogutu
Dissertations (1934 -)
Nitrile hydratase (NHase, E.C.4.2.1.84) is a metalloenzyme that catalyzes the hydration of nitriles into their corresponding amide under ambient conditions. NHase enzymes contain either a non-heme Fe3+ ion or a non-corrin Co3+ ion in their active site. NHase enzymes have industrial applications as biocatalysts in the large-scale production of acrylamide and nicotinamide, though it’s catalytic and biochemical properties are not fully understood. This research project provides insight into the active site maturation process and catalytic mechanism of NHase using peptide model complexes, site-directed mutagenesis and synthesis of deuterated proteins.Insight into the sequential maturation of the NHase active site has been …
The Alpha-Activator Complex, Cellular Maturation, And Catalytic Mechanism Of Iron-Type Nitrile Hydratase, Wasantha Lankathilaka Karunagala Pathiranage
The Alpha-Activator Complex, Cellular Maturation, And Catalytic Mechanism Of Iron-Type Nitrile Hydratase, Wasantha Lankathilaka Karunagala Pathiranage
Dissertations (1934 -)
In industry, chemicals are typically synthesized through catalytically accelerated chemical processes. The use of biocatalysts is an increasingly important trend in achieving environmentally friendly chemical production processes. Nitrile Hydratases (NHases) are well-known biocatalysts that are used by several manufacturers such as Mitsubishi Rayon Corporation and Lonza for the conversion of acrylonitrile to acrylamide and 3-cyanopyridine to nicotinamide, respectively. Amides, in general, are used in polymer preparation, adhesive manufacturing, and the paper industry. Refrigeration is needed in the enzymatic hydration process on the industrial scale to maintain a low reaction temperature to stabilize the NHase enzyme. The use of whole cells …
Synthesis And Reactivity Of Silver Complexes Of Nitrogen Confused Scorpionate Ligands, Fathiya Jahan
Synthesis And Reactivity Of Silver Complexes Of Nitrogen Confused Scorpionate Ligands, Fathiya Jahan
Master's Theses (2009 -)
Scorpionate ligands are one of the most crucial nitrogen donor ligands in coordination chemistry. The scorpionate ligands have served as excellent ligand scaffolds for investigating iron(II) spin crossover chemistry. In this study, the complex, [Fe(HL*)2](OTf)2, 1, where HL* = bis(3,5-dimethylpyrazol-1-yl)(3-1H-pyrazole)methane was prepared which exhibited multiple solid-state structures and solvates. Six crystalline forms of 1 were prepared by controlling the crystallization conditions. Thus, when reagents are combined in CH3CN, an equilibrium mixture of cis- and trans- is established that favors the latter below 310K. Among the six crystal forms, trans-1, trans-1.CH3CN, cis-1 and co-1 undergo SCO below 250K while trans-1.xCH3CN (x=2,4) …
Characterization Of Metal Binding Sites Within The Protein Only Rnase P, Ganga Nilmini Kumari Wijesinghe Mudiyanselage
Characterization Of Metal Binding Sites Within The Protein Only Rnase P, Ganga Nilmini Kumari Wijesinghe Mudiyanselage
Master's Theses (2009 -)
Transfer RNA (tRNA) maturation is an essential step that occurs after transcription and prior to the translation. In all domains of life, an RNA-based ribonuclease (RNase) P catalyzes the cleavage of the phosphodiester bond at the 5′ end of precursor tRNA. However, not all organelles utilize the RNA-based version of RNase P. A recent discovery altering the paradigm of RNase P has revealed that chloroplast organelles, parasitic trypanosomes, and the compact human mitochondrial (mt) genome rely solely on a protein-only 5′ tRNA processing enzyme. Structural and biochemical studies of the RNA-based and protein-based plant RNase P systems suggest that these …
Selective Isomer Formation And Crystallization-Directed Magnetic Behavior In Nitrogen-Confused C-Scorpionate Complexes Of Fe(O3Scf3)2, James R. Gardinier, Kristin J. Meise, Fathiya Jahan, Denan Wang, Sergey V. Lindeman
Selective Isomer Formation And Crystallization-Directed Magnetic Behavior In Nitrogen-Confused C-Scorpionate Complexes Of Fe(O3Scf3)2, James R. Gardinier, Kristin J. Meise, Fathiya Jahan, Denan Wang, Sergey V. Lindeman
Chemistry Faculty Research and Publications
The complex [Fe(HL*)2](OTf)2, 1, where HL* = bis(3,5-dimethylpyrazol-1-yl)(3-1H-pyrazole)methane, was prepared in order to compare its magnetic properties with those of the analogous parent complex, [Fe(HL)2](OTf)2, that lacks methyl groups on pyrazolyl rings and that undergoes spin crossover (SCO) from the low spin (LS) to the high spin (HS) form above room temperature. It was anticipated that this new semibulky derivative should favor the HS state and undergo SCO at a lower temperature range. During this study, six crystalline forms of 1 were prepared by …
Design And Synthesis Of Simplified Analogs Of The Natural Product Sordarin As Potential Antifungal Agents, Yibiao Wu
Dissertations (1934 -)
Invasive fungal infection is a life-threatening illness that causes high mortality, and is especially common among patients with compromised immune systems. However, currently there are only three major classes of clinically useful drugs capable of treating such infections. In addition, due to the fact that drug resistance has become a serious issue especially among patients who suffer from chronic infections, it is urgent to identify new drug candidates, particular those of new classes. The discovery of the natural product sordarin and its novel mechanism of action of inhibiting fungal protein synthesis via the fungal eukaryotic elongation factor 2 (eEF2) led …
Synthesis And Structural Analysis Of Macrocyclic Arenes: Experimental And Computational Insights, Saber Mirzaei
Synthesis And Structural Analysis Of Macrocyclic Arenes: Experimental And Computational Insights, Saber Mirzaei
Master's Theses (2009 -)
Synthesis, properties and applications of macrocyclic molecules have been one ofthe interesting branches of organic chemistry during the past century. Several classes ofmacrocyclic molecules, based on their repeating unit and connectivity pattern, have beendiscovered. Macrocyclic arenes, cyclo[n]veratrylenes, calix[n]arenes and pillar[n]arenes,were among the most interesting and studied molecules. The major difference betweenthese molecules is the methylene-bridged connectivity pattern. In the present thesis, Iattempted to synthesize these molecules using novel approach which has been developedin our group and performing some structural analysis using experimental andcomputational techniques.The first synthesized and investigated molecule is the …
Charge-Transfer Or Excimeric State? Exploring The Nature Of The Excited State In Cofacially Arrayed Polyfluorene Derivatives, Ainur Abzhanova, Lena V. Ivanova, Denan Wang, Tushar S. Navale, Sameh H. Abdelwahed, Maxim Vadimovich Ivanov, Sergey V. Lindeman, Rajendra Rathore, Scott A. Reid
Charge-Transfer Or Excimeric State? Exploring The Nature Of The Excited State In Cofacially Arrayed Polyfluorene Derivatives, Ainur Abzhanova, Lena V. Ivanova, Denan Wang, Tushar S. Navale, Sameh H. Abdelwahed, Maxim Vadimovich Ivanov, Sergey V. Lindeman, Rajendra Rathore, Scott A. Reid
Chemistry Faculty Research and Publications
It is well known that upon electronic excitation various π-stacked dimers readily exhibit excimer formation, facilitated by a perfect sandwich-like arrangement between the chromophores. However, it is unclear whether such a dimer is also capable of electron transfer upon excitation, if a strong electron-donating group is covalently attached. In this work, we probe the nature of the excited state in a series of cofacially arrayed polyfluorene derivatives with electron-rich aromatic donor attached via a methylene linker. Our studies show that in all cases excimer formation is energetically favorable, and promotion of a charge-transfer state in such systems is possible but …