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Comparison Of Various Theoretical Measures Of Aromaticity Within Monosubstituted Benzene, Caleb K. Swain, Steve Scheiner May 2024

Comparison Of Various Theoretical Measures Of Aromaticity Within Monosubstituted Benzene, Caleb K. Swain, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The effects of monosubstitution on the aromaticity of benzene are assessed using a number of different quantitative schemes. The ability of the mobile π-electrons to respond to an external magnetic field is evaluated using several variants of the NICS scheme which calculate the shielding of points along the axis perpendicular to the molecule. Another class of measures is related to the drive toward the uniformity of C-C bond lengths and strengths. Several energetic quantities are devised to approximate an aromatic stabilization energy and the tendency of the molecule to maintain planarity. There is a lack of consistency in that the …


Search For Osme Bonds With Π Systems As Electron Donors, Xin Wang, Qingzhong Li, Steve Scheiner Dec 2023

Search For Osme Bonds With Π Systems As Electron Donors, Xin Wang, Qingzhong Li, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The Osme bond is defined as pairing a Group 8 metal atom as an electron acceptor in a noncovalent interaction with a nucleophile. DFT calculations with the ωB97XD functional consider MO4 (M = Ru, Os) as the Lewis acid, paired with a series of π electron donors C2H2 , C2H4 , C6H6 , C4H5N, C4H4O, and C4H4S. The calculations establish interaction energies in the range between 9.5 and 26.4 kJ/mol. Os engages in stronger interactions than does Ru, …


Relation Between Halogen Bond Strength And Ir And Nmr Spectroscopic Markers, Akhtam Amonov, Steve Scheiner Nov 2023

Relation Between Halogen Bond Strength And Ir And Nmr Spectroscopic Markers, Akhtam Amonov, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The relationship between the strength of a halogen bond (XB) and various IR and NMR spectroscopic quantities is assessed through DFT calculations. Three different Lewis acids place a Br or I atom on a phenyl ring; each is paired with a collection of N and O bases of varying electron donor power. The weakest of the XBs display a C–X bond contraction coupled with a blue shift in the associated frequency, whereas the reverse trends occur for the stronger bonds. The best correlations with the XB interaction energy are observed with the NMR shielding of the C atom directly bonded …


C···O And Si···O Tetrel Bonds: Substituent Effects And Transfer Of The Sif3 Group, Zhihao Niu, Qiaozhuo Wu, Qingzhong Li, Steve Scheiner Jul 2023

C···O And Si···O Tetrel Bonds: Substituent Effects And Transfer Of The Sif3 Group, Zhihao Niu, Qiaozhuo Wu, Qingzhong Li, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The tetrel bond (TB) between 1,2-benzisothiazol-3-one-2-TF3-1,1-dioxide (T = C, Si) and the O atom of pyridine-1-oxide (PO) and its derivatives (PO-X, X = H, NO2, CN, F, CH3, OH, OCH3, NH2, and Li) is examined by quantum chemical means. The Si···O TB is quite strong, with interaction energies approaching a maximum of nearly 70 kcal/mol, while the C···O TB is an order of magnitude weaker, with interaction energies between 2.0 and 2.6 kcal/mol. An electron-withdrawing substituent on the Lewis base weakens this TB, while an electron-donating group has the opposite …


Assessing The Possibility And Properties Of Types I And Ii Chalcogen Bonds, Steve Scheiner May 2023

Assessing The Possibility And Properties Of Types I And Ii Chalcogen Bonds, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Type I and II halogen bonds are well-recognized motifs that commonly occur within crystals. Quantum calculations are applied to examine whether such geometries might occur in their closely related chalcogen bond cousins. Homodimers are constructed of the R1R2C=Y and R1R2Y monomers, wherein Y represents a chalcogen atom, S, Se, or Te; R1 and R2 refer to either H or F. A Type II (T2) geometry wherein the lone pair of one Y is closely aligned with a σ-hole of its partner represents a stable arrangement for all except YH2, although not all such structures are true minima. The symmetric T1 …


Structural And Functional Studies Of Mtr4 And The Tramp Rna Surveillance Complex, Sean Johnson Sep 2022

Structural And Functional Studies Of Mtr4 And The Tramp Rna Surveillance Complex, Sean Johnson

Funded Research Records

No abstract provided.


Collaborative Research: Developing Advanced Magnesium Electrolytes Toward Low Cost, High Energy Density Mg Batteries, Tianbiao Liu Aug 2022

Collaborative Research: Developing Advanced Magnesium Electrolytes Toward Low Cost, High Energy Density Mg Batteries, Tianbiao Liu

Funded Research Records

No abstract provided.


Collaborative Research: Surface-Specific Aerosol Chemistry: Direct Observations, Kinetics, And Environmental Impact, Yi Rao Jun 2022

Collaborative Research: Surface-Specific Aerosol Chemistry: Direct Observations, Kinetics, And Environmental Impact, Yi Rao

Funded Research Records

No abstract provided.


Phosphomimetic Tyrosine Mutations In Spa47 Inhibit Type Three Secretion Atpase Activity And Shigella Virulence Phenotype, Koleton D. Hardy, Nicholas E. Dickenson Feb 2022

Phosphomimetic Tyrosine Mutations In Spa47 Inhibit Type Three Secretion Atpase Activity And Shigella Virulence Phenotype, Koleton D. Hardy, Nicholas E. Dickenson

Chemistry and Biochemistry Faculty Publications

Shigella is a highly infectious human pathogen responsible for 269 million infections and 200,000 deaths per year. Shigella virulence is absolutely reliant on the injection of effector proteins into the host cell cytoplasm via its type three secretion system (T3SS). The protein Spa47 is a T3SS ATPase whose activity is essential for the proper function of the Shigella T3SS needle-like apparatus through which effectors are secreted. A phosphoproteomics study recently found several Shigella T3SS proteins, including Spa47, to be tyrosine phosphorylated, suggesting a means of regulating Spa47 enzymatic activity, T3SS function, and overall Shigella virulence. The work presented here employs …


Nickel Catalyzed Electrochemical C-C Cross-Coupling Reactions, T. Leo Liu Aug 2021

Nickel Catalyzed Electrochemical C-C Cross-Coupling Reactions, T. Leo Liu

Funded Research Records

No abstract provided.


Anion–Anion Interactions In Aerogen-Bonded Complexes. Influence Of Solvent Environment, Anna Grabarz, Mariusz Michalczyk, Wiktor Zierkiewicz, Steve Scheiner Apr 2021

Anion–Anion Interactions In Aerogen-Bonded Complexes. Influence Of Solvent Environment, Anna Grabarz, Mariusz Michalczyk, Wiktor Zierkiewicz, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Ab initio calculations are applied to the question as to whether a AeX5− anion (Ae = Kr, Xe) can engage in a stable complex with another anion: F−, Cl−, or CN−. The latter approaches the central Ae atom from above the molecular plane, along its C5 axis. While the electrostatic repulsion between the two anions prevents their association in the gas phase, immersion of the system in a polar medium allows dimerization to proceed. The aerogen bond is a weak one, with binding energies less than 2 kcal/mol, even in highly polar aqueous solvent. The complexes are …


Noncovalent Bonds Through Sigma And Pi-Hole Located On The Same Molecule. Guiding Principles And Comparisons, Wiktor Ziekiewicz, Mariusz Michalczyk, Steve Scheiner Mar 2021

Noncovalent Bonds Through Sigma And Pi-Hole Located On The Same Molecule. Guiding Principles And Comparisons, Wiktor Ziekiewicz, Mariusz Michalczyk, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Over the last years, scientific interest in noncovalent interactions based on the presence of electron-depleted regions called σ-holes or π-holes has markedly accelerated. Their high directionality and strength, comparable to hydrogen bonds, has been documented in many fields of modern chemistry. The current review gathers and digests recent results concerning these bonds, with a focus on those systems where both σ and π-holes are present on the same molecule. The underlying principles guiding the bonding in both sorts of interactions are discussed, and the trends that emerge from recent work offer a guide as to how one might design systems …


Collaborative Research: Development Of A Better Understanding Of Ambient Rm Chemistry, Reactions Forming, And Methods For Measurement, Seth Lyman Mar 2021

Collaborative Research: Development Of A Better Understanding Of Ambient Rm Chemistry, Reactions Forming, And Methods For Measurement, Seth Lyman

Funded Research Records

No abstract provided.


Career: Time-Resolved Studies Of Charge Transfer And Chemical Reactivity At Photoelectrode-Electrolyte Interfaces, Yi Rao Feb 2021

Career: Time-Resolved Studies Of Charge Transfer And Chemical Reactivity At Photoelectrode-Electrolyte Interfaces, Yi Rao

Funded Research Records

No abstract provided.


Eager Sentinels: The Pcr-Free Biosensor For A Fast, Simple, And Sensitive Detection Of Rna, Artavazd Badalyan Jan 2021

Eager Sentinels: The Pcr-Free Biosensor For A Fast, Simple, And Sensitive Detection Of Rna, Artavazd Badalyan

Funded Research Records

No abstract provided.


Comparison Of Bifurcated Halogen With Hydrogen Bonds, Steve Scheiner Jan 2021

Comparison Of Bifurcated Halogen With Hydrogen Bonds, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Bifurcated halogen bonds are constructed with FBr and FI as Lewis acids, paired with NH3 and NCH bases. The first type considered places two bases together with a single acid, while the reverse case of two acids sharing a single base constitutes the second type. These bifurcated systems are compared with the analogous H-bonds wherein FH serves as the acid. In most cases, a bifurcated system is energetically inferior to a single linear bond. There is a larger energetic cost to forcing the single σ-hole of an acid to interact with a pair of bases, than the other way …


Development Of An Understanding Of Reactive Mercury In Ambient Air: A Review, Mae Sexauer Gustin, Sarrah M. Dunham-Cheatham, Jiaoyan Huang, Steve Lindberg, Seth N. Lyman Jan 2021

Development Of An Understanding Of Reactive Mercury In Ambient Air: A Review, Mae Sexauer Gustin, Sarrah M. Dunham-Cheatham, Jiaoyan Huang, Steve Lindberg, Seth N. Lyman

Chemistry and Biochemistry Faculty Publications

This review focuses on providing the history of measurement efforts to quantify and characterize the compounds of reactive mercury (RM), and the current status of measurement methods and knowledge. RM collectively represents gaseous oxidized mercury (GOM) and that bound to particles. The presence of RM was first recognized through measurement of coal-fired power plant emissions. Once discovered, researchers focused on developing methods for measuring RM in ambient air. First, tubular KCl-coated denuders were used for stack gas measurements, followed by mist chambers and annular denuders for ambient air measurements. For ~15 years, thermal desorption of an annular KCl denuder in …


“Bottled” Spiro-Doubly Aromatic Trinuclear [Pd2ru]+ Complexes, Maksim Kulichenko, Nikita Fedik, Anna Monfredini, Alvaro Muñoz-Castro, Davide Balestri, Alexander I. Boldyrev, Giovanni Maestri Oct 2020

“Bottled” Spiro-Doubly Aromatic Trinuclear [Pd2ru]+ Complexes, Maksim Kulichenko, Nikita Fedik, Anna Monfredini, Alvaro Muñoz-Castro, Davide Balestri, Alexander I. Boldyrev, Giovanni Maestri

Chemistry and Biochemistry Faculty Publications

Following an ongoing interest in the study of transition metal complexes with exotic bonding networks, we report herein the synthesis of a family of heterobimetallic triangular clusters involving Ru and Pd atoms. These are the first examples of trinuclear complexes combining these nuclei. Structural and bonding analyses revealed both analogies and unexpected differences for these [Pd2Ru]+ complexes compared to their parent [Pd3]+ peers. Noticeably, participation of the Ru atom in the π-aromaticity of the coordinated benzene ring makes the synthesized compound the second reported example of ‘bottled’ double aromaticity. This can also be referred …


A Sandwich-Type Cluster Containing Ge@Pd3 Planar Fragment Flanked By Aromatic Nonagermanide Caps, Hong-Lei Xu, Nikolay V. Tkachenko, Zi-Chuan Wang, Wei-Xing Chen, Lei Qiao, Alvaro Muñoz-Castro, Alexander I. Boldyrev, Zhong-Ming Sun Oct 2020

A Sandwich-Type Cluster Containing Ge@Pd3 Planar Fragment Flanked By Aromatic Nonagermanide Caps, Hong-Lei Xu, Nikolay V. Tkachenko, Zi-Chuan Wang, Wei-Xing Chen, Lei Qiao, Alvaro Muñoz-Castro, Alexander I. Boldyrev, Zhong-Ming Sun

Chemistry and Biochemistry Faculty Publications

Sandwich-type clusters with the planar fragment containing a heterometallic sheet have remained elusive. In this work, we introduce the [K(2,2,2-crypt)]4{(Ge9)2[η6-Ge(PdPPh3)3]} complex that contains a heterometallic sandwich fragment. The title compound is structurally characterized by means of single-crystal X-ray diffraction, which reveals the presence of an unusual heteroatomic metal planar fragment Ge@Pd3. The planar fragment contains a rare formal zerovalent germanium core and a peculiar bonding mode of sp2-Ge@(PdPPh3)3 trigonal planar structure, whereas the nonagermanide fragments act as capping ligands. The …


Versatility Of The Cyano Group In Intermolecular Interactions, Steve Scheiner Sep 2020

Versatility Of The Cyano Group In Intermolecular Interactions, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Several cyano groups are added to an alkane, alkene, and alkyne group so as to construct a Lewis acid molecule with a positive region of electrostatic potential in the area adjoining these substituents. Although each individual cyano group produces only a weak π-hole, when two or more such groups are properly situated, they can pool their π-holes into one much more intense positive region that is located midway between them. A NH3 base is attracted to this site, where it forms a strong noncovalent bond to the Lewis acid, amounting to as much as 13.6 kcal/mol. The precise nature …


Determining The Structure And Function Of Newly Discovered Immune Systems, Ryan N. Jackson Sep 2020

Determining The Structure And Function Of Newly Discovered Immune Systems, Ryan N. Jackson

Funded Research Records

No abstract provided.


Effect Of Carbon Hybridization In C—F Bond As An Electron Donor In Triel Bonds, Qingqing Yang, Zongqing Chi, Qingzhong Li, Steve Scheiner Aug 2020

Effect Of Carbon Hybridization In C—F Bond As An Electron Donor In Triel Bonds, Qingqing Yang, Zongqing Chi, Qingzhong Li, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The ability of the F atom of HC≡CF, H2C=CHF and H3CCH2F to serve as an electron donor to the triel (Tr) atom of TrR3 in the context of a triel bond is assessed by ab initio calculations. The triel bond formed by Csp3—F is strongest, as high as 30 kcal/mol, followed by Csp2—F, and then by Csp—F whose triel bonds can be as small as 1 kcal/mol. The noncovalent bond strength diminishes in the order Tr = Al > Ga > B, consistent with the intensity of the π-hole …


Comparison Of Accelerated Solvent Extraction (Ase) And Energized Dispersive Guided Extraction (Edge) For The Analysis Of Pesticides In Leaves, Ashlie D. Kinross, Kimberly J. Hageman, William J. Doucette, Alexandria L. Foster Jul 2020

Comparison Of Accelerated Solvent Extraction (Ase) And Energized Dispersive Guided Extraction (Edge) For The Analysis Of Pesticides In Leaves, Ashlie D. Kinross, Kimberly J. Hageman, William J. Doucette, Alexandria L. Foster

Chemistry and Biochemistry Faculty Publications

Various techniques have been evaluated for the extraction and cleanup of pesticides from environmental samples. In this work, a Selective Pressurized Liquid Extraction (SPLE) method for pesticides was developed using a Thermo Fisher Scientific Accelerated Solvent Extraction (ASE) system. This instrument was compared to the newly introduced (2017) extraction instrument, the Energized Dispersive Guided Extraction (EDGE) system, which combines Pressurized Liquid Extraction (PLE) and dispersive Solid Phase Extraction (dSPE). We first optimized the SPLE method using the ASE instrument for pesticide extraction from alfalfa leaves using layers of Florisil and graphitized carbon black (GCB) downstream of the leaf homogenate in …


Collaborative Research: Mechanism And Target Recognition Of Protein Arginine Methyltransferases (Prmts), Joan Hevel Jul 2020

Collaborative Research: Mechanism And Target Recognition Of Protein Arginine Methyltransferases (Prmts), Joan Hevel

Funded Research Records

No abstract provided.


Strong Temporal Variability In Methane Fluxes From Natural Gas Well Pad Soils, Seth N. Lyman, Huy N. Q. Tran, Marc L. Mansfield, Ric Bowers, Ann Smith May 2020

Strong Temporal Variability In Methane Fluxes From Natural Gas Well Pad Soils, Seth N. Lyman, Huy N. Q. Tran, Marc L. Mansfield, Ric Bowers, Ann Smith

Bingham Research Center

We measured methane and carbon dioxide fluxes at natural gas well pad soils and undisturbed soils in the Rocky Mountain and Gulf Coast regions of the United States, including producing and gas storage wells. We collected both short-term (15 min) and multi-day (between 3 and 8), continuous measurements at 47 well pads and two undisturbed locations. Methane fluxes varied by more than an order of magnitude over periods as short as 30 min (e.g., 19–593 mg m−2 h−1 in one instance), and diurnal and seasonal variability was also significant (e.g., spring-to-fall change from 509 to 14174 mg m …


Influence Of Adjuvants On Pesticide Soil-Air Partition Coefficients: Laboratory Measurements And Predicted Effects On Volatilization, Supta Das, Kimberly J. Hageman May 2020

Influence Of Adjuvants On Pesticide Soil-Air Partition Coefficients: Laboratory Measurements And Predicted Effects On Volatilization, Supta Das, Kimberly J. Hageman

Chemistry and Biochemistry Faculty Publications

A solid-phase fugacity meter was used to measure the soil–air partition coefficients of three semivolatile pesticides (chlorpyrifos, pyrimethanil, and trifluralin) in the absence of additional adjuvants (Ksoil–air,AI), as part of commercial formulations (Ksoil–air,formulation), and as formulation mixtures with an additional spray adjuvant added (Ksoil–air,formulation+spray adjuvant). Chlorpyrifos Ksoil–air,formulation values were also measured over 15–30 °C, allowing for the change in internal energy of the phase transfer reaction (Δsoil–airU) to be calculated and compared to the Δsoil–airU for Ksoil–air,AI from the literature. Measured Ksoil–air values …


N3-Ligated Nickel(Ii) Diketonate Complexes: Synthesis, Characterization And Evaluation Of O2 Reactivity, Josiah G. D. Elsberg, Austin Peterson, Amy L. Fuller, Lisa M. Berreau May 2020

N3-Ligated Nickel(Ii) Diketonate Complexes: Synthesis, Characterization And Evaluation Of O2 Reactivity, Josiah G. D. Elsberg, Austin Peterson, Amy L. Fuller, Lisa M. Berreau

Chemistry and Biochemistry Faculty Publications

Interest in O2-dependent aliphatic carbon–carbon (C–C) bond cleavage reactions of first row divalent metal diketonate complexes stems from the desire to further understand the reaction pathways of enzymes such as DKE1 and to extract information to develop applications in organic synthesis. A recent report of O2-dependent aliphatic C–C bond cleavage at ambient temperature in Ni(II) diketonate complexes supported by a tridentate nitrogen donor ligand [(MBBP)Ni(PhC(O)CHC(O)Ph)]Cl (7-Cl; MBBP = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine) in the presence of NEt3 spurred our interest in further examining the chemistry of such complexes. A series of new TERPY-ligated Ni(II) diketonate complexes of the …


Co Sense And Release Flavonols: Progress Toward The Development Of An Analyte Replacement Photocorm For Use In Living Cells, Marina Popova, Tatiana Soboleva, Abby D. Benninghoff, Lisa M. Berreau Apr 2020

Co Sense And Release Flavonols: Progress Toward The Development Of An Analyte Replacement Photocorm For Use In Living Cells, Marina Popova, Tatiana Soboleva, Abby D. Benninghoff, Lisa M. Berreau

Chemistry and Biochemistry Faculty Publications

Carbon monoxide (CO) is a signaling molecule in humans. Prior research suggests that therapeutic levels of CO can have beneficial effects in treating a variety of physiological and pathological conditions. To facilitate understanding of the role of CO in biology, molecules that enable fluorescence detection of CO in living systems have emerged as an important class of chemical tools. A key unmet challenge in this field is the development of fluorescent analyte replacement probes that replenish the CO that is consumed during detection. Herein, we report the first examples of CO sense and release molecules that involve combining a common …


Modeling The Alkaline Hydrolysis Of Diaryl Sulfate Diesters: A Mechanistic Study, Klaudia Szeler, Nicholas H. Williams, Alvan C. Hengge, Shina C. Kamerlin Apr 2020

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 …


Boron-Made N2: Realization Of A B≡B Triple Bond In The B2al3− Cluster, Nikita Fedik, Chaonan Mu, Ivan A. Popov, Wei Wang, Jie Wang, Haopeng Wang, Kit H. Bowen, Alexander I. Boldyrev, Xinxing Zhang Apr 2020

Boron-Made N2: Realization Of A B≡B Triple Bond In The B2al3− Cluster, Nikita Fedik, Chaonan Mu, Ivan A. Popov, Wei Wang, Jie Wang, Haopeng Wang, Kit H. Bowen, Alexander I. Boldyrev, Xinxing Zhang

Chemistry and Biochemistry Faculty Publications

Until now, all B≡B triple bonds have been achieved by adopting two ligands in the L→B≡B←L manner. Herein, we report an alternative route of designing the B≡B bonds based on the assumption that by acquiring two extra electrons, an element with the atomic number Z can have properties similar to those of the element with the atomic number Z+2. Specifically, we show that due to the electron donation from Al to B, the negatively charged B≡B kernel in the B2Al3− cluster mimics a triple N≡N bond. Comprehensive computational searches reveal that the global minimum structure of B2Al3− exhibits a …