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Chemistry

2019

Chemistry Faculty Research and Publications

Articles 1 - 19 of 19

Full-Text Articles in Physical Sciences and Mathematics

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 Dec 2019

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 …

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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 Dec 2019

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 …

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Proton Transfer Versus Hydrogen Bonding In A Reduced Iron Porphyrin Nitrosyl Complex, Md. Hafizur Rahman, Yilin Liu, Michael D. Ryan Sep 2019

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, …

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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 Sep 2019

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 …

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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 Sep 2019

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 …

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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 Sep 2019

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 …

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Β-Fluorofentanyls Are Ph-Sensitive Mu Opioid Receptor Agonists, Ricardo Rosas Jr., Xi-Ping Huang, Bryan L. Roth, Chris Dockendorff Aug 2019

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 …

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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 Jul 2019

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 …

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Calculation Of Molecular Vibrational Spectra On A Quantum Annealer, Alexander Teplukhin, Brian K. Kendrick, Dmitri Babikov Jul 2019

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: …

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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 Jul 2019

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 …

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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 Jun 2019

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 …

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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 Apr 2019

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 …

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Synthesis Of Simplified Azasordarin Analogs As Potential Antifungal Agents, Yibiao Wu, Chris Dockendorff Mar 2019

Synthesis Of Simplified Azasordarin Analogs As Potential Antifungal Agents, Yibiao Wu, Chris Dockendorff

Chemistry Faculty Research and Publications

A new series of simplified azasordarin analogs was synthesized using as key steps a Diels–Alder reaction to generate a highly substituted bicyclo[2.2.1]heptane core, followed by a subsequent nitrile alkylation. Several additional strategies were investigated for the generation of the key tertiary nitrile or aldehyde thought to be required for inhibition at the fungal protein eukaryotic elongation factor 2. This new series also features a morpholino glycone previously reported in semisynthetic sordarin derivatives with broad spectrum antifungal activity. Despite a lack of activity against Candida albicans for these early de novo analogs, the synthetic route reported here permits more comprehensive modifications …

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Cooperative Transport In A Multi-Particle, Multi-Dimensional Flashing Ratchet, Ofer Kedem, Emily A. Weiss Mar 2019

Cooperative Transport In A Multi-Particle, Multi-Dimensional Flashing Ratchet, Ofer Kedem, Emily A. Weiss

Chemistry Faculty Research and Publications

Random and undirected forces are rectified in biological and synthetic systems using ratcheting mechanisms, which employ periodic asymmetric potentials and nonequilibrium conditions to produce useful transport. The density of motors or transported particles is known to strongly affect the nature and efficacy of transport in biological systems, as well as in synthetic ratchets and active swimmer systems. While experimental ratchet implementations typically employ potentials varying in two dimensions (2D), the role of the density of interacting particles in such a system has not been modeled. Prompted by experimental observations and building upon previous simulations, this paper describes the ratcheting process …

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The Ratio Of The Number Of States In Asymmetric And Symmetric Ozone Molecules Deviates From The Statistical Value Of 2, Igor Gayday, Alexander Teplukhin, Dmitri Babikov Mar 2019

The Ratio Of The Number Of States In Asymmetric And Symmetric Ozone Molecules Deviates From The Statistical Value Of 2, Igor Gayday, Alexander Teplukhin, Dmitri Babikov

Chemistry Faculty Research and Publications

Accurate calculations of vibrational states in singly and doubly substituted ozone molecules are carried out, up to dissociation threshold. Analysis of these spectra reveals noticeable deviations from the statistical factor of 2 for the ratio between the number of states in asymmetric and symmetric ozone molecules. It is found that, for the lower energy parts of spectra, the ratio is less than 2 in the singly substituted ozone molecules, but it is more than 2 in the doubly substituted ozone molecules. However, the upper parts of spectra, just below dissociation thresholds, exhibit a different behavior. In this energy range, the …

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C–H/Π And C–H–O Interactions In Concert: A Study Of The Anisole–Methane Complex Using Resonant Ionization And Velocity Mapped Ion Imaging, James Makuvaza, Damian Kokkin, John Loman, Scott A. Reid Mar 2019

C–H/Π And C–H–O Interactions In Concert: A Study Of The Anisole–Methane Complex Using Resonant Ionization And Velocity Mapped Ion Imaging, James Makuvaza, Damian Kokkin, John Loman, Scott A. Reid

Chemistry Faculty Research and Publications

Noncovalent forces such as hydrogen bonding, halogen bonding, π–π stacking, and C–H/π and C–H/O interactions hold the key to such chemical processes as protein folding, molecular self-assembly, and drug–substrate interactions. Invaluable insight into the nature and strength of these forces continues to come from the study of isolated molecular clusters. In this work, we report on a study of the isolated anisole–methane complex, where both C–H/π and C–H/O interactions are possible, using a combination of theory and experiments that include mass-selected two-color resonant two-photon ionization spectroscopy, two-color appearance potential (2CAP) measurements, and velocity mapped ion imaging (VMI). Using 2CAP and …

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Proton-Coupled Reduction Of An Iron Nitrosyl Porphyrin In The Protic Ionic Liquid Nanodomain, Abderrahman Atifi, Piotr J. Mak, Michael D. Ryan Feb 2019

Proton-Coupled Reduction Of An Iron Nitrosyl Porphyrin In The Protic Ionic Liquid Nanodomain, Abderrahman Atifi, Piotr J. Mak, Michael D. Ryan

Chemistry Faculty Research and Publications

The one-electron reduction of many molecules becomes much more favorable if combined with proton transfers or strong hydrogen bonding. Protic room temperature ionic liquids (RTILs), which can form nanodomains in solutions with molecular solvents (MS), can provide an efficient avenue for this process. In this work, we report on the voltammetry, UV/visible and resonance Raman spectroelectrochemistryof Fe(TPP)(NO) in the presence of aprotic/protic ammonium-based ionic liquids. While aprotic RTILs did shift the reduction to more positive potentials, similar shifts could be observed at much lower concentrations of diethylmethylammonium triflate (HAmOTf, a protic ionic liquid). Deconvolution of the rotating ring-disk electrode (RRDE) …

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Design And Evaluation Of Heterobivalent Par1–Par2 Ligands As Antagonists Of Calcium Mobilization, Mark W. Majewski, Disha M. Gandhi, Ricardo Rosas Jr., Revathi Kodall, Leggy A. Arnold, Chris Dockendorff Jan 2019

Design And Evaluation Of Heterobivalent Par1–Par2 Ligands As Antagonists Of Calcium Mobilization, Mark W. Majewski, Disha M. Gandhi, Ricardo Rosas Jr., Revathi Kodall, Leggy A. Arnold, Chris Dockendorff

Chemistry Faculty Research and Publications

A novel class of bivalent ligands targeting putative protease-activated receptor (PAR) heteromers has been prepared based upon reported antagonists for the subtypes PAR1 and PAR2. Modified versions of the PAR1 antagonist RWJ-58259 containing alkyne adapters were connected via cycloaddition reactions to azide-capped polyethylene glycol (PEG) spacers attached to imidazopyridazine-based PAR2 antagonists. Initial studies of the PAR1–PAR2 antagonists indicated that they inhibited G alpha q-mediated calcium mobilization in endothelial and cancer cells driven by both PAR1 and PAR2 agonists. Compounds of this novel class hold promise for the prevention of restenosis, cancer cell metastasis, and other proliferative disorders.

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Investigation Of Solvation And Solvent Coordination Effects In Iron Porphyrin Nitrosyls By Infrared Spectroelectrochemistry And Dft Calculations, Md. Hafizur Rahman, Michael D. Ryan Jan 2019

Investigation Of Solvation And Solvent Coordination Effects In Iron Porphyrin Nitrosyls By Infrared Spectroelectrochemistry And Dft Calculations, Md. Hafizur Rahman, Michael D. Ryan

Chemistry Faculty Research and Publications

Visible and infrared spectroelectrochemistry of Fe(OEPone)(NO) (H2OEPone = octaethylporphinone) were examined in methylene chloride and THF. The visible spectra of Fe(OEPone)(NO) were similar in both solvents. Unlike other ferrous porphyrin nitrosyls, a six-coordinate complex was formed with THF as a ligand. This led to two nitrosyl bands in the infrared spectrum. The absorbance of these bands depended on the concentration of THF in the solution. Solvation and coordination effects on the carbonyl and nitrosyl bands were observed for both the nitrosyl and reduced-nitrosyl complexes. DFT calculations were carried out to interpret the spectral changes.

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