Physical Sciences and Mathematics Commons^™

Rapid Generation Of P(V)-F Bonds Through The Use Of Sulfone Iminium Fluoride Reagents, Lucy P. Miller, James A. Vogel, Shiraz Harel, Jenna M. Krussman, Patrick R. Melvin

Chemistry Faculty Research and Scholarship

Phosphorus–fluorine bonds have become increasingly relevant in the pharmaceutical industry. To continue their exploration, more efficient synthetic methods are needed. Here, we report the application of sulfone iminium fluoride (SIF) reagents to the synthesis of P(V)–F bonds. The SIF reagents promote the deoxyfluorination of phosphinic acids in just 60 s with excellent yields and scope. The same P(V)–F products can also be synthesized from secondary phosphine oxides using an SIF reagent.

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 …

Investigation On The Synthesis, Application And Structural Features Of Heteroaryl 1,2-Diketones, Robert J. Wehrle, Alexander Rosen, Thu Vu Nguyen, Kalyn Koons, Eric Jump, Mason Bullard, Natalie Wehrle, Adam Stockfish, Patrick M. Hare, Abdurrahman Atesin, Tülay A. Ateşin, Lili Ma

Chemistry Faculty Publications and Presentations

A set of unsymmetrical heteroaryl 1,2-diketones were synthesized by a heteroarylation/oxidation sequence with up to 65% isolated yields. Palladium catalyst XPhos Pd G4 and SeO2 were the key reagents used in this methodology, and microwave irradiation was utilized to facilitate an efficient and ecofriendly process. The application of heteroaryl 1,2-diketones is demonstrated through the synthesis of an unsymmetrical 2-phenyl-3-(pyridin-3-yl)quinoxaline (5a) from 1-phenyl-2-(pyridin-3-yl)ethane-1,2-dione (4a). The lowest energy conformations of 4a and 5a were located using Density Functional Theory (DFT) at the M06-2X/def2-TZVP level of theory. Two lowest energy conformations of 4a differ with respect to the position of the N atom …

Calcium Bistriflimide-Mediated Sulfur (Vi)–Fluoride Exchange (Sufex): Mechanistic Insights Toward Instigating Catalysis, Nicholas Ball, Brian Han, Samuel R. Khasnavis, Matthew Nwerem, Michael Bertagna, O Maduka Ogba

Pomona Faculty Publications and Research

We report a mechanistic investigation of calcium bistriflimide-mediated sulfur(VI)–fluoride exchange (SuFEx) between sulfonyl fluorides and amines. We determine the likely pre-activation resting state─a calcium bistriflimide complex with ligated amines─thus allowing for corroborated calculation of the SuFEx activation barrier at ∼21 kcal/mol, compared to 21.5 ± 0.14 kcal/mol derived via kinetics experiments. Transition state analysis revealed: (1) a two-point calcium-substrate contact that activates the sulfur(VI) center and stabilizes the leaving fluoride and (2) a 1,4-diazabicyclo[2.2.2]octane additive that provides Brønsted-base activation of the nucleophilic amine. Stable Ca–F complexes upon sulfonamide formation are likely contributors to inhibited catalytic turnover, and a proof-of-principle redesign …

Valence-, Dipole-And Quadropole-Bound Electronically Excited States Of Closed-Shell Anions Formed By Deprotonation Of Cyano-And Ethynyl-Disubstituted Polycyclic Aromatic Hydrocarbons, Marie E. Strauss, Taylor J. Santaloci, Ryan C. Fortenberry

Faculty and Student Publications

Dicyano-functionalized benzene and naphthalene anion derivatives exhibit a relatively rich population of electronically excited states in stark contrast to many assumptions regarding the photophysics of anions in general. The present work has quantum chemically analyzed the potential electronically excited states of closed-shell anions created by replacing hydrogen atoms with valence-bound lone pairs in benzene and naphthalene difunctionalized with combinations of-CN and-C2H. Dicyanobenzene anion derivatives can exhibit dipole-bound excited states as long as the cyano groups are not in para position to one another. This also extends to cyanoethynylbenzene anions as well as deprotonated dicyano-and cyanoethynylnaphthalene anion derivatives. Diethynyl functionalization is …

Synthesis Of Highly Reactive Sulfone Iminium Fluorides And Their Use In Deoxyfluorination And Sulfur Fluoride Exchange Chemistry, James A. Vogel, Rania Hammami, Ara Ko, Hiya Datta, Yael N. Eiben, Karley J. Labenne, Ellis C. Mccarver, Ebrar Z. Yilmaz, Patrick R. Melvin

Chemistry Faculty Research and Scholarship

We report the synthesis of sulfone iminium fluorides (SIFs), a reactive class of sulfur(VI) molecules. The synthesis is tolerant of a variety of substituents on the sulfur and nitrogen components. The SIF reagents were applied to the deoxyfluorination of alcohols and carboxylic acids, providing high yields of fluorinated products in 60 s at room temperature. The SIF reagents were then utilized in sulfur fluoride exchange (SuFEx), creating the first ionic SuFEx products to date.

Atomic-Resolution 1.3 Å Crystal Structure, Inhibition By Sulfate, And Molecular Dynamics Of The Bacterial Enzyme Dape, Matthew Kochert, Boguslaw P. Nocek, Thahani S. Habeeb Mohammad, Elliot Gild, Kaitlyn Lovato, Tahirah K. Heath, Richard C. Holz, Kenneth W. Olsen, Daniel P. Becker Ph.D.

Chemistry: Faculty Publications and Other Works

We report the atomic-resolution (1.3 Å) X-ray crystal structure of an open conformation of the dapE-encoded N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE, EC 3.5.1.18) from Neisseria meningitidis. This structure [Protein Data Bank (PDB) entry 5UEJ] contains two bound sulfate ions in the active site that mimic the binding of the terminal carboxylates of the N-succinyl-l,l-diaminopimelic acid (l,l-SDAP) substrate. We demonstrated inhibition of DapE by sulfate (IC50 = 13.8 ± 2.8 mM). Comparison with other DapE structures in the PDB demonstrates the flexibility of the interdomain connections of this protein. This high-resolution structure was then utilized as the …

Electronically Excited States Of Closed-Shell, Cyano-Functionalized Polycyclic Aromatic Hydrocarbon Anions, Taylor J. Santaloci, Ryan C. Fortenberry

Faculty and Student Publications

Few anions exhibit electronically excited states, and, if they do, the one or two possible excitations typically transpire beyond the visible spectrum into the near-infrared. These few, red-shifted electronic absorption features make anions tantalizing candidates as carriers of the diffuse interstellar bands (DIBs), a series of mostly unknown, astronomically ubiquitous absorption features documented for over a century. The recent interstellar detection of benzonitrile implies that cyano-functionalized polycyclic aromatic hydrocarbon (PAH) anions may be present in space. The presently reported quantum chemical work explores the electronic properties of deprotonated benzene, naphthalene, and anthracene anions functionalized with a single cyano group. Both …

Chemical Synthesis Of Homogeneous Human E-Cadherin N-Linked Glycopeptides: Stereoselective Convergent Glycosylation And Chemoselective Solid-Phase Aspartylation, Chen Zeng, Bin Sun, Xuefeng Cao, Joshua Zhu, Olawale Micheal Oluwadahunsi, Ding Liu, He Zhu, Jiabin Zhang, Qing Zhang, Gaolan Zhang, Christopher Andrew Gibbons, Yunpeng Liu, Jun Zhou, Peng George Wang

Faculty Work Comprehensive List

We report herein an efficient chemical synthesis of homogeneous human E-cadherin N-linked glycopeptides consisting of a heptapeptide sequence adjacent to the Asn-633 N-glycosylation site with representative N-glycan structures, including a conserved trisaccharide, a core-fucosylated tetrasaccharide, and a complex-type biantennary octasaccharide. The key steps are a chemoselective on-resin aspartylation using a pseudoproline-containing peptide and stereoselective glycosylation using glycosyl fluororide as a donor. This synthetic strategy demonstrates potential utility in accessing a wide range of homogeneous N-linked glycopeptides for the examination of their biological function.

Phosphonium Versus Ammonium Compact Polyelectrolyte Complex Networks With Alginate-Comparing Their Properties And Cargo Encapsulation., Tristan D. Harrison, Alexandre J. Salmon, John R. De Bruyn, Paul J. Ragogna, Elizabeth R. Gillies

Chemistry Publications

Phosphonium and ammonium polymers can be combined with polyanions to form polyelectrolyte complex (PEC) networks, with potential application in self-healing materials and drug delivery vehicles. While various structures and compositions have been explored, to the best of our knowledge, analogous ammonium and phosphonium networks have not been directly compared to evaluate the effects of phosphorus versus nitrogen cations on the network properties. In this study, we prepared PECs from sodium alginate and poly[triethyl(4-vinylbenzyl)phosphonium chloride], poly[triethyl(4-vinylbenzyl)ammonium chloride], poly[tri(

Modeling The Alkaline Hydrolysis Of Diaryl Sulfate Diesters: A Mechanistic Study, Klaudia Szeler, Nicholas H. Williams, Alvan C. Hengge, Shina C. Kamerlin

Chemistry and Biochemistry Faculty Publications

Phosphate and sulfate esters have important roles in regulating cellular processes. However, while there has been substantial experimental and computational investigation of the mechanisms and the transition states involved in phosphate ester hydrolysis, there is far less work on sulfate ester hydrolysis. Here, we report a detailed computational study of the alkaline hydrolysis of diaryl sulfate diesters, using different DFT functionals as well as mixed implicit/explicit solvation with varying numbers of explicit water molecules. We consider the impact of the computational model on computed linear free-energy relationships (LFER) and the nature of the transition states (TS) involved. We obtain good …

Ability Of Ir And Nmr Spectral Data To Distinguish Between A Tetrel Bond And A Hydrogen Bond, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The placement of a nucleophile X along the R-CH3 axis of a methyl group can be described as either a trifurcated H-bond or as a tetrel bond between C and X. Quantum calculation of the vibrational and NMR spectral features of a number of systems are used to provide a framework by which to distinguish between the presence of a tetrel or H-bond. Both cationic and neutral methyl-containing Lewis acids (SMe3+, NMe4+, SMe2) are paired with both neutral and anionic Lewis bases (NH3, OH2, OCHNH2, OCH3-, OH-, HCOO-). As the base is moved away from the R-CH3 axis of the …

Monitoring The Health Of Glen Helen Nature Preserve: Fall 2012 Sediment And Water, Audrey E. Mcgowin Ph.D., Triet Minh Truong

Chemistry Student Publications

This poster presents the results for environmental testing in Glen Helen by the Special Topics in Analytical Chemistry course at Wright State University under the direction of Professor Audrey McGowin in Spring 2012. Water quality data are presented for the Yellow Spring in Yellow Springs, Ohio for April and May of 2012. Other test sites range from locations along Yellow Springs Creek to the covered bridge near Little Miami River.

This poster was created by Triet M. Truong.

Monitoring The Health Of Glen Helen Nature Preserve: Spring 2012 Sediment And Water, Audrey E. Mcgowin Ph.D., Triet Minh Truong, David Kammler Ph.D., Joe Solch

Chemistry Student Publications

This poster presents the results for environmental testing in Glen Helen by the Special Topics in Analytical Chemistry course at Wright State University under the direction of Professor Audrey McGowin in Spring 2012. Water quality data are presented for the Yellow Spring in Yellow Springs, Ohio for April and May of 2012. Other test sites range from locations along Yellow Springs Creek to the covered bridge near Little Miami River.

This poster was created by Triet M. Truong.

Variation Of Anions In Layered Double Hydroxides: Effects On Dispersion And Fire Properties, Linjiang Wang, Shengpei Shu, Dan Chen, Charles A. Wilkie

Chemistry Faculty Research and Publications

Layered double hydroxides (LDHs) are interesting materials for nanocomposite formation because one can vary the identity of the metals, the anions and the stoichiometry to see the effect of these on the ability of the nano-material to disperse in a polymer and to see what effect dispersion has on the properties of the polymer. In this study, the anions 2-ethylhexyl sulfate (SEHS), bis(2-ethylhexyl) phosphate (HDEHP) and dodecyl benzenesulfonate (SDBS) have been utilized as the charge balancing anions to synthesize organo-LDHs. Nanocomposites of poly(methyl methacrylate) (PMMA) and polystyrene (PS) with organo-LDHs were prepared both by melt blending and bulk polymerization. X-ray …

Anion And Cation-Yield Spectroscopy Of Core-Excited Sf6, Maria Novella Piancastelli, Wayne C. Stolte, Renaud Guillemin, A. Wolska, M. M. Sant'anna, Dennis W. Lindle

Chemistry and Biochemistry Faculty Research

We report an extensive study on total and partial-ion-yield spectroscopy around both the S 2p and F 1s thresholds in SF₆. All positive and negative single-ion channels have been measured. Below the F 1s threshold we detect a large variation in relative intensity of the resonant structures according to the specific channel monitored, indicating selective fragmentation. Above threshold, at variance with previous cases described by us, we detect high-intensity structures related to shape resonances not only in the cation channels but also for the anions. We discuss the applicability and limits of a model we …

Mössbauer Spectral Study Of The Magnetocaloric Femnp₁₋ₓasₓ Compounds, Raphäel P. Hermann, Ojied Tegus, Ekkehard H. Brück, K. H. J. Buschow, Frank R. De Boer, Gary J. Long, Fernande Grandjean

Chemistry Faculty Research & Creative Works

The magnetic phase transitions in the FeMnP_1-xAs_x compounds with x= 0.25, 0.35, 0.45, 0.50, and 0.55, have been studied by iron-57 Mössbauer spectroscopy. The ferromagnetic and antiferromagnetic spectra have been analyzed with a model that takes into account the random distribution of the P and As near-neighbor anions of a given iron site. This distribution is a binomial distribution of the contributions to the spectra of each iron with n As near neighbors. A magnetostriction model has been used to characterize the temperature induced paramagnetic to ferromagnetic first-order phase transition and order parameters, η_F=2.6, 2.3, …

Photofragmentation Dynamics Of Core-Excited Water By Anion-Yield Spectroscopy, Wayne C. Stolte, M. M. Sant'anna, Gunnar Ohrwall, Maria Novella Piancastelli, I. Dominguez-Lopez, Dennis W. Lindle

Chemistry and Biochemistry Faculty Research

Partial-anion and- cation yields from H₂O are presented for photon energies near the oxygen K edge. The O^- yield exhibits a feature above threshold attributed to doubly excited states, in contrast to the H^- and cation yields, which are nearly featureless above threshold. Additionally, the lack of the OH^- fragment indicates radiative decay and provides a negligible amount of anion formation.

Order-Disorder Phase Transitions In Kno2 , Csno2, And Tlno2 Crystals: A Molecular Dynamics Study, Chun-Gang Duan, Wai-Ning Mei, Robert W. Smith, Jianjun Liu, M. M. Ossowski, John R. Hardy

Physics Faculty Publications

The order-disorder phase transitions of KNO2 , CsNO2, and TlNO2 have been studied using parameter-free molecular dynamics simulation. It is found that the phase transitions in nitrites investigated are driven by the rotations of the NO2 2 ions about different axes together with displacements of cations and anions. We successfully reproduce the high-temperature phases of these nitrites, i.e., the NaCl-like structure for KNO2 and CsCl-like structure for Cs(Tl)NO2. Based on the investigation of the radial distribution function of the cations and anions, we explain why KNO2 and Cs(Tl)NO2 form quite different low-temperature phases.