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Design, Evolution, And Evaluation Of A General Chemistry-Bridging Course, Scott A. Reid
Design, Evolution, And Evaluation Of A General Chemistry-Bridging Course, Scott A. Reid
Chemistry Faculty Research and Publications
General chemistry I/II courses are important gateway courses for a variety of STEM majors, as poor performance in these courses is often associated with lower rates of student success and retention. Much research has explored preparatory or remedial strategies to improve student outcomes. In this article, we report a different approach, which involved the development of a bridging or intervention course designed to capture students who are not or have not succeeded in general chemistry I and prepare them to retake the course in the following semester or summer. The course was initially developed as an eight-week module in the …
Reversible Dioxygen Binding To Co(Ii) Complexes With Noninnocent Ligands, Praveen Kumar, Laxmi Devkota, Maximilian C. Casey, Anne A. Fischer, Sergey V. Lindeman, Adam T. Fiedler
Reversible Dioxygen Binding To Co(Ii) Complexes With Noninnocent Ligands, Praveen Kumar, Laxmi Devkota, Maximilian C. Casey, Anne A. Fischer, Sergey V. Lindeman, Adam T. Fiedler
Chemistry Faculty Research and Publications
A series of mononuclear Co(II) complexes with noninnocent (redox-active) ligands are prepared that exhibit metal–ligand cooperativity during the reversible binding of O2. The complexes have the general formula, [CoII(LS,N)(TpR2)] (R = Me, Ph), where LS,N is a bidentate o-aminothiophenolate and TpR2 is a hydrotris(pyrazol-1-yl)borate scorpionate with R-substituents at the 3- and 5-positions. Exposure to O2 at room temperature results in one-electron oxidation and deprotonation of LS,N. The oxidized derivatives possess substantial “singlet diradical” character arising from antiferromagnetic coupling between an iminothiosemiquinonate (ITSQ•–) …
Mixed Quantum/Classical Theory For Collisional Quenching Of Pahs In The Interstellar Media, Bikramaditya Mandal, Carolin Joy, Alexander Semenov, Dmitri Babikov
Mixed Quantum/Classical Theory For Collisional Quenching Of Pahs In The Interstellar Media, Bikramaditya Mandal, Carolin Joy, Alexander Semenov, Dmitri Babikov
Chemistry Faculty Research and Publications
A computationally affordable methodology is developed to predict cross sections and rate coefficients for collisional quenching and excitation of large molecules in space, such as PAHs. Mixed quantum/classical theory of inelastic scattering (MQCT) is applied, in which quantum state-to-state transitions between the internal states of the molecule are described using a time-dependent Schrodinger equation, while the scattering of collision partners is described classically using mean-field trajectories. To boost the numerical performance even further, a decoupling scheme for the equations of motion and a Monte Carlo sampling of the initial conditions are implemented. The method is applied to compute cross sections …
Effect Of Ligands And Their Removal On The Au Nanoparticle-Catalyzed Reduction Of 4-Nitrophenol, Nicholas Langer, Ofer Kedem
Effect Of Ligands And Their Removal On The Au Nanoparticle-Catalyzed Reduction Of 4-Nitrophenol, Nicholas Langer, Ofer Kedem
Chemistry Faculty Research and Publications
The catalytic activity of gold nanoparticles (Au NPs) is strongly affected by the organic ligands coating them, which afford colloidal stability and are most commonly attached during the synthesis of the Au NPs. However, different ligands also produce Au NPs of different sizes and morphologies, complicating the study of the impact of the ligands themselves. Alternatively, postsynthetic ligand exchange risks incomplete exchanges and a mixed ligand shell, as well as colloidal instability. Here, Au NPs are immobilized on glass supports to afford truly ligand-free, solvent-stable Au nanoislands (NIs). The catalytic activity of Au NIs, uncoated and coated with a variety …
Enantioselective Synthesis Of Enantioisotopomers With Quantitative Chiral Analysis By Chiral Tag Rotational Spectroscopy, Mitchell D. Mills, Reilly E. Sonstrom, Zoua Pa Vang, Justin L. Neill, Haley N. Scolati, Channing T. West, Brooks H. Pate, Joseph R. Clark
Enantioselective Synthesis Of Enantioisotopomers With Quantitative Chiral Analysis By Chiral Tag Rotational Spectroscopy, Mitchell D. Mills, Reilly E. Sonstrom, Zoua Pa Vang, Justin L. Neill, Haley N. Scolati, Channing T. West, Brooks H. Pate, Joseph R. Clark
Chemistry Faculty Research and Publications
Fundamental to the synthesis of enantioenriched chiral molecules is the ability to assign absolute configuration at each stereogenic center, and to determine the enantiomeric excess for each compound. While determination of enantiomeric excess and absolute configuration is often considered routine in many facets of asymmetric synthesis, the same determinations for enantioisotopomers remains a formidable challenge. Here, we report the first highly enantioselective metal-catalyzed synthesis of enantioisotopomers that are chiral by virtue of deuterium substitution along with the first general spectroscopic technique for assignment of the absolute configuration and quantitative determination of the enantiomeric excess of isotopically chiral molecules. Chiral tag …
Uv- And Visible-Light Photopatterning Of Molecular Gradients Using The Thiol–Yne Click Reaction, Mark Mitmoen, Ofer Kedem
Uv- And Visible-Light Photopatterning Of Molecular Gradients Using The Thiol–Yne Click Reaction, Mark Mitmoen, Ofer Kedem
Chemistry Faculty Research and Publications
The rational design of chemical coatings is used to control surface interactions with small molecules, biomolecules, nanoparticles, and liquids as well as optical and other properties. Specifically, micropatterned surface coatings have been used in a wide variety of applications, including biosensing, cell growth assays, multiplexed biomolecule interaction arrays, and responsive surfaces. Here, a maskless photopatterning process is studied, using the photocatalyzed thiol–yne “click” reaction to create both binary and gradient patterns on thiolated surfaces. Nearly defect-free patterns are produced by first coating glass surfaces with mercaptopropylsilatrane, a silanizing agent that forms smoother self-assembled monolayers than the commonly used 3-mercaptopropyltrimethoxysilane. Photopatterning …
Highly Regioselective Copper-Catalyzed Transfer Hydrodeuteration Of Unactivated Terminal Alkenes, Albert Reyes, Emanuel Rivera Torres, Zoua Pa Vang, Joseph R. Clark
Highly Regioselective Copper-Catalyzed Transfer Hydrodeuteration Of Unactivated Terminal Alkenes, Albert Reyes, Emanuel Rivera Torres, Zoua Pa Vang, Joseph R. Clark
Chemistry Faculty Research and Publications
Catalytic transfer hydrodeuteration of unactivated alkenes is challenging because of the requirement that similar hydrogen and deuterium undergo selective insertion across a π-bond. We now report a highly regioselective catalytic transfer hydrodeuteration of unactivated terminal alkenes across a variety of heteroatom- or heterocycle-containing substrates. The base-metal-catalyzed reaction is also demonstrated on two complex natural products. Reaction studies indicate modular conditions that can also be extended to perform either an alkene transfer hydrogenation or transfer deuteration.
Molecular Dynamics On Quantum Annealers, Igor Gaidai, Dmitri Babikov, Alexander Teplukhin, Brian K. Kendrick, Susan M. Mniszewski, Yu Zhang, Sergei Tretiak, Pavel A. Dub
Molecular Dynamics On Quantum Annealers, Igor Gaidai, Dmitri Babikov, Alexander Teplukhin, Brian K. Kendrick, Susan M. Mniszewski, Yu Zhang, Sergei Tretiak, Pavel A. Dub
Chemistry Faculty Research and Publications
In this work we demonstrate a practical prospect of using quantum annealers for simulation of molecular dynamics. A methodology developed for this goal, dubbed Quantum Differential Equations (QDE), is applied to propagate classical trajectories for the vibration of the hydrogen molecule in several regimes: nearly harmonic, highly anharmonic, and dissociative motion. The results obtained using the D-Wave 2000Q quantum annealer are all consistent and quickly converge to the analytical reference solution. Several alternative strategies for such calculations are explored and it was found that the most accurate results and the best efficiency are obtained by combining the quantum annealer with …
Triple Oxygen Isotope Constraints On Atmospheric O2 And Biological Productivity During The Mid-Proterozoic, Peng Liu, Jingjin Liu, Aoshaung Ji, Christopher T. Reinhard, Noah J. Planavsky, Dmitri Babikov, Raymond G. Najjar, James F. Kasting
Triple Oxygen Isotope Constraints On Atmospheric O2 And Biological Productivity During The Mid-Proterozoic, Peng Liu, Jingjin Liu, Aoshaung Ji, Christopher T. Reinhard, Noah J. Planavsky, Dmitri Babikov, Raymond G. Najjar, James F. Kasting
Chemistry Faculty Research and Publications
Reconstructing the history of biological productivity and atmospheric oxygen partial pressure (pO2) is a fundamental goal of geobiology. Recently, the mass-independent fractionation of oxygen isotopes (O-MIF) has been used as a tool for estimating pO2 and productivity during the Proterozoic. O-MIF, reported as Δ′17O, is produced during the formation of ozone and destroyed by isotopic exchange with water by biological and chemical processes. Atmospheric O-MIF can be preserved in the geologic record when pyrite (FeS2) is oxidized during weathering, and the sulfur is redeposited as sulfate. Here, sedimentary sulfates from …
2d Covalent Organic Frameworks With An Incorporated Manganese Complex For Light Driven Carbon Dioxide Reduction, Denan Wang, Daniel Streater, Yun Peng, Jier Huang
2d Covalent Organic Frameworks With An Incorporated Manganese Complex For Light Driven Carbon Dioxide Reduction, Denan Wang, Daniel Streater, Yun Peng, Jier Huang
Chemistry Faculty Research and Publications
Covalent organic frameworks (COFs) have emerged as a novel class of crystalline porous photocatalytic materials due to their unique properties such as large surface area, tunable porosity, and rigid structure. In this work, we report the direct incorporation of a manganese CO2 molecular catalyst (MC) into COFs (Mn−TTA-COF) and the evaluation of its capability as photocatalyst for visible light driven CO2 reduction to form CO. We found that the photocatalytic activity of Mn−TTA-COF is quite low, which mainly results from the elimination of the CO ligand in the Mn MC upon light illumination, rendering its short duration in …
Spectrumsdt: A Program For Parallel Calculation Of Coupled Rotational-Vibrational Energies And Lifetimes Of Bound States And Scattering Resonances In Triatomic Systems, Igor Gayday, Alexander Teplukhin, Jonathan Moussa, Dmitri Babikov
Spectrumsdt: A Program For Parallel Calculation Of Coupled Rotational-Vibrational Energies And Lifetimes Of Bound States And Scattering Resonances In Triatomic Systems, Igor Gayday, Alexander Teplukhin, Jonathan Moussa, Dmitri Babikov
Chemistry Faculty Research and Publications
We present SpectrumSDT – a program for calculations of energies and lifetimes of bound rotational-vibrational states below and scattering resonances above the dissociation threshold on a global potential energy surface of a triatomic system, which may include stable molecules, weekly-bound van-der-Waals complexes, and unbound atom + diatom scattering systems. Large-amplitude vibrational motion is treated explicitly using hyper-spherical coordinates. Three options for the rotational-vibrational interaction are supported: uncoupled (symmetric top rotor), partially coupled (to include interaction between several nearest states only) and full-coupled (vibrating asymmetric-top rotor). In addition to energies and lifetimes, SpectrumSDT is able to integrate ro-vibrational wave functions over …
Dissecting Monomer-Dimer Equilibrium Of An Rnase P Protein Provides Insight Into The Synergistic Flexibility Of 5’ Leader Pre-Trna Recognition, Danyun Zeng, Ainur Abzhanova, Benjamin P. Brown, Nicholas J. Reiter
Dissecting Monomer-Dimer Equilibrium Of An Rnase P Protein Provides Insight Into The Synergistic Flexibility Of 5’ Leader Pre-Trna Recognition, Danyun Zeng, Ainur Abzhanova, Benjamin P. Brown, Nicholas J. Reiter
Chemistry Faculty Research and Publications
Ribonuclease P (RNase P) is a universal RNA-protein endonuclease that catalyzes 5’ precursor-tRNA (ptRNA) processing. The RNase P RNA plays the catalytic role in ptRNA processing; however, the RNase P protein is required for catalysis in vivo and interacts with the 5’ leader sequence. A single P RNA and a P protein form the functional RNase P holoenzyme yet dimeric forms of bacterial RNase P can interact with non-tRNA substrates and influence bacterial cell growth. Oligomeric forms of the P protein can also occur in vitro and occlude the 5’ leader ptRNA binding interface, presenting a challenge in accurately defining …
Electronic Structures And Spectroscopic Signatures Of Diiron Intermediates Generated By O2 Activation Of Nonheme Iron(Ii)–Thiolate Complexes, Danushka M. Ekanayake, Dao Pham, Andrew L. Probst, Joshua R. Miller, Cordina V. Popescu, Adam T. Fiedler
Electronic Structures And Spectroscopic Signatures Of Diiron Intermediates Generated By O2 Activation Of Nonheme Iron(Ii)–Thiolate Complexes, Danushka M. Ekanayake, Dao Pham, Andrew L. Probst, Joshua R. Miller, Cordina V. Popescu, Adam T. Fiedler
Chemistry Faculty Research and Publications
The activation of O2 at thiolate–ligated iron(II) sites is essential to the function of numerous metalloenzymes and synthetic catalysts. Iron–thiolate bonds in the active sites of nonheme iron enzymes arise from either coordination of an endogenous cysteinate residue or binding of a deprotonated thiol-containing substrate. Examples of the latter include sulfoxide synthases, such as EgtB and OvoA, that utilize O2 to catalyze tandem S–C bond formation and S-oxygenation steps in thiohistidine biosyntheses. We recently reported the preparation of two mononuclear nonheme iron–thiolate complexes (1 and 2) that serve as structural active-site models of substrate-bound EgtB …
Covalent Immobilization Of Molecular Complexes On Metal-Organic Frameworks Towards Robust And Highly Efficient Heterogeneous Water Oxidation Catalysts, Xiangming Liang, Sizhou Yang, Junyi Yang, Wanjun Sun, Xiangyang Li, Baochun Ma, Jier Huang, Jiangwei Zhang, Lele Duan, Yong Ding
Covalent Immobilization Of Molecular Complexes On Metal-Organic Frameworks Towards Robust And Highly Efficient Heterogeneous Water Oxidation Catalysts, Xiangming Liang, Sizhou Yang, Junyi Yang, Wanjun Sun, Xiangyang Li, Baochun Ma, Jier Huang, Jiangwei Zhang, Lele Duan, Yong Ding
Chemistry Faculty Research and Publications
The major challenges to practical implementation of efficient noble metal based molecular water oxidation catalysts are their stability and recycle ability. Herein, noble metal Ru based molecular water oxidation catalysts were covalently anchored in MOFs through “amide bond” as bridges, which leads to the formation of high-efficiency and robust heterogeneous catalysts for water oxidation reaction. We show that the efficiency for CeIV-driven water oxidation was significantly enhanced by 120 times when the Ru molecules were immobilized on the frameworks of MIL-101(Cr). The relationship between recycle stability and the structure of the Ru complexes covalently anchored in MOFs was …
Catalytic Transfer Deuteration And Hydrodeuteration: Emerging Techniques To Selectively Transform Alkenes And Alkynes To Deuterated Alkanes, Zoua Pa Vang, Samuel J. Hintzsche, Joseph R. Clark
Catalytic Transfer Deuteration And Hydrodeuteration: Emerging Techniques To Selectively Transform Alkenes And Alkynes To Deuterated Alkanes, Zoua Pa Vang, Samuel J. Hintzsche, Joseph R. Clark
Chemistry Faculty Research and Publications
Increasing demand for deuterium-labeled organic molecules has spurred a renewed interest in selective methods for deuterium installation. Catalytic transfer deuteration and transfer hydrodeuteration are emerging as powerful techniques for the selective incorporation of deuterium into small molecules. These reactions not only obviate the use of D2 gas and pressurized reaction setups but provide new opportunities for selectively installing deuterium into small molecules. Commercial or readily synthesized deuterium donors are typically employed as easy-to-handle reagents for transfer deuteration and hydrodeuteration reactions. In this minireview, recent advances in the catalytic transfer deuteration and hydrodeuteration of alkenes and alkynes for the selective …
Efficient Method For An Approximate Treatment Of The Coriolis Effect In Calculations Of Quantum Dynamics And Spectroscopy, With Application To Scattering Resonances In Ozone, Igor Gayday, Dmitri Babikov
Efficient Method For An Approximate Treatment Of The Coriolis Effect In Calculations Of Quantum Dynamics And Spectroscopy, With Application To Scattering Resonances In Ozone, Igor Gayday, Dmitri Babikov
Chemistry Faculty Research and Publications
A numerical approach is developed to capture the effect of rotation–vibration coupling in a practically affordable way. In this approach only a limited number of adjacent rotational components are considered to be coupled, while the couplings to other rotational components are neglected. This partially coupled (PC) approach permits to reduce the size of Hamiltonian matrix significantly, which enables the calculations of ro-vibrational states above dissociation threshold (scattering resonances) for large values of total angular momentum. This method is employed here to reveal the role of the Coriolis effect in the ozone formation reaction at room temperature, dominated by large values …
In Situ Activated Co3–XNiXO4 As A Highly Active And Ultrastable Electrocatalyst For Hydrogen Generation, Kailu Guo, Yantao Wang, Junfeng Huang, Min Lu, Hua Li, Yong Peng, Pinxian Xi, Haoli Zhang, Jier Huang, Siyu Lu, Cailing Xu
In Situ Activated Co3–XNiXO4 As A Highly Active And Ultrastable Electrocatalyst For Hydrogen Generation, Kailu Guo, Yantao Wang, Junfeng Huang, Min Lu, Hua Li, Yong Peng, Pinxian Xi, Haoli Zhang, Jier Huang, Siyu Lu, Cailing Xu
Chemistry Faculty Research and Publications
The spinel Co3O4 has emerged as a promising alternative to noble-metal-based electrocatalysts for electrochemical water electrolysis in alkaline medium. However, pure Co3O4, despite having high activity in anodic water oxidation, remains inactive toward the hydrogen evolution reaction (HER). Here, a Ni-doped Co3O4(Co3–xNixO4) prepared by a simple method exhibits favorable HER activity and stability (>300 h, whether in 1 M KOH or the realistic 30 wt % KOH solution) after in situ electrochemical activation, outperforming almost all of the oxide-based electrocatalysts. More …
Four Isotope-Labeled Recombination Pathways Of Ozone Formation, Dmitri Babikov, Elizaveta Grushnikova, Igor Gayday, Alexander Teplukhin
Four Isotope-Labeled Recombination Pathways Of Ozone Formation, Dmitri Babikov, Elizaveta Grushnikova, Igor Gayday, Alexander Teplukhin
Chemistry Faculty Research and Publications
A theoretical approach is developed for the description of all possible recombination pathways in the ozone forming reaction, without neglecting any process a priori, and without decoupling the individual pathways one from another. These pathways become physically distinct when a rare isotope of oxygen is introduced, such as 18O, which represents a sensitive probe of the ozone forming reaction. Each isotopologue of O3 contains two types of physically distinct entrance channels and two types of physically distinct product wells, creating four recombination pathways. Calculations are done for singly and doubly substituted isotopologues of ozone, eight rate coefficients …
Unraveling A Trifecta Of Weak Non-Covalent Interactions: The Dissociation Energy Of The Anisole-Ammonia 1:1 Complex, John L. Loman, James T. Makuvaza, Damian L. Kokkin, Scott A. Reid
Unraveling A Trifecta Of Weak Non-Covalent Interactions: The Dissociation Energy Of The Anisole-Ammonia 1:1 Complex, John L. Loman, James T. Makuvaza, Damian L. Kokkin, Scott A. Reid
Chemistry Faculty Research and Publications
The anisole-ammonia 1:1 complex is a challenge for both experiment and theory. Early studies supported a non-planar structure, involving a trifecta of weak non-covalent interactions: N-H/O, N-H/π, and C-H/N. The calculated structure and binding energy of the complex proved remarkably sensitive to the level of theory employed. Here, we report the first experimental measurement of the ground state dissociation energy of the complex, and derive an excited (S1) state dissociation energy that is in excellent agreement with the cutoff observed in the experimental excitation spectrum. Results are compared with previous predictions and new calculations based on benchmarked Density …
The Electronic Properties Of Ni(Pnn) Pincer Complexes Modulate Activity In Catalytic Hydrodehalogenation Reactions, Denan Wang, James R. Gardinier
The Electronic Properties Of Ni(Pnn) Pincer Complexes Modulate Activity In Catalytic Hydrodehalogenation Reactions, Denan Wang, James R. Gardinier
Chemistry Faculty Research and Publications
Three chloronickel(II) complexes of PNN‐ pincer ligands with pyrazolyl and diphenylphosphino donors appended to different arms of diarylamido anchors were prepared and fully characterized. The three derivatives (1‐OMe, 1‐Me, 1‐CF3) differ only by the identity of the para‐aryl substituent on the pyrazolyl arm with 1‐OMe being 310 mV easier to oxidize than 1‐CF3. All three complexes are competent catalysts for hydrodehalogenation reactions of 1‐bromooctane and a variety of aryl halides in dimethylacetamide using NaBH4 as both base and hydride source. Comparative studies using diverse substrates showed that catalytic activity correlates with electron donor properties; …
Iron(Iii)-Bipyridine Incorporated Metal–Organic Frameworks For Photocatalytic Reduction Of Co2 With Improved Performance, Yuan-Ping Wei, Sizhuo Yang, Peng Wang, Jin-Han Guo, Jier Huang, Wei-Yin Sun
Iron(Iii)-Bipyridine Incorporated Metal–Organic Frameworks For Photocatalytic Reduction Of Co2 With Improved Performance, Yuan-Ping Wei, Sizhuo Yang, Peng Wang, Jin-Han Guo, Jier Huang, Wei-Yin Sun
Chemistry Faculty Research and Publications
Metal–organic frameworks (MOFs) represent an emerging class of platforms to assemble single site photocatalysts for artificial photosynthesis. In this work, we report a new CO2 reduction photocatalyst (UiO-68-Fe-bpy) based on a robust Zr(IV)-MOF platform with incorporated Fe(bpy)Cl3 (bpy refers to the 4′-methyl-[2,2′-bipyridine] moiety) via amine–aldehyde condensation. We show that this hybrid catalyst can reduce CO2 to form CO under visible light illumination with excellent selectivity and enhanced activity with respect to its parent MOF and corresponding homogeneous counterpart. Using steady state and transient absorption (TA) spectroscopy, we show that the enhanced photocatalytic activity of UiO-68-Fe-bpy is attributed …
P450 Cyp17a1 Variant With A Disordered Proton Shuttle Assembly Retains Peroxo-Mediated Lyase Efficiency, Yilin Liu, Ilia G. Denisov, Yelena V. Grinkova, Stephen G. Silgar, James R. Kincaid
P450 Cyp17a1 Variant With A Disordered Proton Shuttle Assembly Retains Peroxo-Mediated Lyase Efficiency, Yilin Liu, Ilia G. Denisov, Yelena V. Grinkova, Stephen G. Silgar, James R. Kincaid
Chemistry Faculty Research and Publications
Human cytochrome P450 CYP17A1 first catalyzes hydroxylation at the C17 position of either pregnenolone (PREG) or progesterone (PROG), and a subsequent C17−C20 bond scission to produce dehydroepiandrosterone (DHEA) or androstenedione (AD). In the T306A mutant, replacement of the Threonine 306 alcohol functionality, essential for efficient proton delivery in the hydroxylase reaction, has only a small effect on the lyase activity. In this work, resonance Raman spectroscopy is employed to provide crucial structural insight, confirming that this mutant, with its disordered proton shuttle, fails to generate essential hydroxylase pathway intermediates, accounting for the loss in hydroxylase efficiency. Significantly, …
Probing The Magnetic Anisotropy Of Co(Ii) Complexes Featuring Redox-Active Ligands, Praveen Kumar, Daniel J. Santa Lucia, Kinga Kaniewska-Laskowska, Sergey Lindeman, Andrew Ozarowski, J. Krzystek, Mykhaylo Ozerov, Joshua Telser, John F. Berry, Adam T. Fiedler
Probing The Magnetic Anisotropy Of Co(Ii) Complexes Featuring Redox-Active Ligands, Praveen Kumar, Daniel J. Santa Lucia, Kinga Kaniewska-Laskowska, Sergey Lindeman, Andrew Ozarowski, J. Krzystek, Mykhaylo Ozerov, Joshua Telser, John F. Berry, Adam T. Fiedler
Chemistry Faculty Research and Publications
Coordination complexes that possess large magnetic anisotropy (otherwise known as zero-field splitting, ZFS) have possible applications in the field of magnetic materials, including single molecule magnets (SMMs). Previous studies have explored the role of coordination number and geometry in controlling the magnetic anisotropy and SMM behavior of high-spin (S = 3/2) Co(II) complexes. Building upon these efforts, the present work examines the impact of ligand oxidation state and structural distortions on the spin states and ZFS parameters of pentacoordinate Co(II) complexes. The five complexes included in this study (1–5) have the general formula, [Co(TpPh2 …
Copper-Catalyzed Formal Transfer Hydrogenation/Deuteration Of Aryl Alkynes, Samantha E. Sloane, Albert Reyes, Zoua Pa Vang, Lingzi Li, Kiera T. Behlow, Joseph R. Clark
Copper-Catalyzed Formal Transfer Hydrogenation/Deuteration Of Aryl Alkynes, Samantha E. Sloane, Albert Reyes, Zoua Pa Vang, Lingzi Li, Kiera T. Behlow, Joseph R. Clark
Chemistry Faculty Research and Publications
A copper-catalyzed reduction of alkynes to alkanes and deuterated alkanes is described under transfer hydrogenation and transfer deuteration conditions. Commercially available alcohols and silanes are used interchangeably with their deuterated analogues as the hydrogen or deuterium sources. Transfer deuteration of terminal and internal aryl alkynes occurs with high levels of deuterium incorporation. Alkyne-containing complex natural product analogues undergo transfer hydrogenation and transfer deuteration selectively, in high yield. Mechanistic experiments support the reaction occurring through a cis-alkene intermediate and demonstrate the possibility for a regioselective alkyne transfer hydrodeuteration reaction.
Ion Pairing Versus Solvation Of Dinitrobenzene Anions In Room-Temperature Ionic Liquids (Rtils): Vibrational Signatures Of Rtil–Substrate Interactions, Abderrahman Atifi, Piotr J. Mak, Michael D. Ryan
Ion Pairing Versus Solvation Of Dinitrobenzene Anions In Room-Temperature Ionic Liquids (Rtils): Vibrational Signatures Of Rtil–Substrate Interactions, Abderrahman Atifi, Piotr J. Mak, Michael D. Ryan
Chemistry Faculty Research and Publications
The mechanism of solvation of ions by ionic liquids is more complex than solvation in most molecular solvents as the ionic liquid itself provides the counter ion. Solvation and ion pairing of anionic substrates in room-temperature ionic liquids (RTILs) were investigated using resonance Raman spectroscopy and DFT calculations. The purpose of this study was to differentiate between the formation of discrete cation/anion structures and a double-layer cloud of counter ions without specific atomic interactions between the ionic species. In acetonitrile/RTIL mixtures, the radical anion and dianion of dinitrobenzene (DNB) are stabilized by RTILs through solvation and ion pairing. The formation …
Solving Complex Eigenvalue Problems On A Quantum Annealer With Applications To Quantum Scattering Resonances, Alexander Teplukhin, Brian K. Kendrick, Dmitri Babikov
Solving Complex Eigenvalue Problems On A Quantum Annealer With Applications To Quantum Scattering Resonances, Alexander Teplukhin, Brian K. Kendrick, Dmitri Babikov
Chemistry Faculty Research and Publications
Quantum computing is a new and rapidly evolving paradigm for solving chemistry problems. In previous work, we developed the Quantum Annealer Eigensolver (QAE) and applied it to the calculation of the vibrational spectrum of a molecule on the D-Wave quantum annealer. However, the original QAE methodology was applicable to real symmetric matrices only. For many physics and chemistry problems, the diagonalization of complex matrices is required. For example, the calculation of quantum scattering resonances can be formulated as a complex eigenvalue problem where the real part of the eigenvalue is the resonance energy and the imaginary part is proportional to …
Distance Dependent Energy Transfer Dynamics From A Molecular Donor To A Zeolitic Imidazolate Framework Acceptor, Wenhui Hu, Fan Yang, Nick Pietraszak, Jing Gu, Jier Huang
Distance Dependent Energy Transfer Dynamics From A Molecular Donor To A Zeolitic Imidazolate Framework Acceptor, Wenhui Hu, Fan Yang, Nick Pietraszak, Jing Gu, Jier Huang
Chemistry Faculty Research and Publications
Zeolitic Imidazolate frameworks (ZIFs) have been demonstrated as promising light harvesting and photocatalytic materials for solar energy conversion. To facilitate their application in photocatalysis, it is essential to develop a fundamental understanding of their light absorption properties and energy transfer dynamics. In this work, we report distance-dependent energy transfer dynamics from a molecular photosensitizer (RuN3) to ZIF-67, where the distance between RuN3 and ZIF-67 is finely tuned by depositing an ultrathin Al2O3 layer on the ZIF-67 surface using an atomic layer deposition (ALD) method. We show that energy transfer time decreases with increasing distance between RuN3 and …
Unravelling A Long-Lived Ligand-To-Metal Cluster Charge Transfer State In Ce–Tcpp Metal Organic Frameworks, Sizhou Yang, Wenhui Hu, James Nayakuchena, Christian Fiankor, Cunming Liu, Eli Diego Kinigstein, Jian Zhang, Xiaoyi Zhang, Jier Huang
Unravelling A Long-Lived Ligand-To-Metal Cluster Charge Transfer State In Ce–Tcpp Metal Organic Frameworks, Sizhou Yang, Wenhui Hu, James Nayakuchena, Christian Fiankor, Cunming Liu, Eli Diego Kinigstein, Jian Zhang, Xiaoyi Zhang, Jier Huang
Chemistry Faculty Research and Publications
Metal organic frameworks (MOFs) have emerged as promising photocatalytic materials for solar energy conversion. However, a fundamental understanding of light harvesting and charge separation (CS) dynamics in MOFs remains underexplored, yet they are key factors that determine the efficiency of photocatalysis. Herein, we report the design and CS dynamics of the Ce–TCPP MOF using ultrafast spectroscopic methods.
Solving The Conundrum: Widespread Proteins Annotated For Urea Metabolism In Bacteria Are Carboxyguanidine Deiminases Mediating Nitrogen Assimilation From Guanidine, Nicholas O. Schneider, Lambros J. Tassoulas, Danyun Zeng, Amanda J. Laseke, Nicholas J. Reiter, Lawrence P. Wackett, Martin St. Maurice
Solving The Conundrum: Widespread Proteins Annotated For Urea Metabolism In Bacteria Are Carboxyguanidine Deiminases Mediating Nitrogen Assimilation From Guanidine, Nicholas O. Schneider, Lambros J. Tassoulas, Danyun Zeng, Amanda J. Laseke, Nicholas J. Reiter, Lawrence P. Wackett, Martin St. Maurice
Chemistry Faculty Research and Publications
Free guanidine is increasingly recognized as a relevant molecule in biological systems. Recently, it was reported that urea carboxylase acts preferentially on guanidine, and consequently, it was considered to participate directly in guanidine biodegradation. Urea carboxylase combines with allophanate hydrolase to comprise the activity of urea amidolyase, an enzyme predominantly found in bacteria and fungi that catalyzes the carboxylation and subsequent hydrolysis of urea to ammonia and carbon dioxide. Here, we demonstrate that urea carboxylase and allophanate hydrolase from Pseudomonas syringae are insufficient to catalyze the decomposition of guanidine. Rather, guanidine is decomposed to ammonia through the combined activities of …
Computationally-Guided Investigation Of Dual Amine/Pi Lewis Acid Catalysts For Direct Additions Of Aldehydes And Ketones To Unactivated Alkenes And Alkynes, Eric Greve, Jacob D. Porter, Chris Dockendorff
Computationally-Guided Investigation Of Dual Amine/Pi Lewis Acid Catalysts For Direct Additions Of Aldehydes And Ketones To Unactivated Alkenes And Alkynes, Eric Greve, Jacob D. Porter, Chris Dockendorff
Chemistry Faculty Research and Publications
Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehydes/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that pyridine-2,6-bis(oxazoline) (PyBOX)-Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan's imidazolidinone organocatalyst for aldehyde/ketone activation to …