Chemistry Commons^™

Bimetallic Complexes Supported By A Redox-Active Ligand With Fused Pincer-Type Coordination Sites, Denan Wang, Sergey V. Lindeman, Adam T. Fiedler

Chemistry Faculty Research and Publications

The remarkable chemistry of mononuclear complexes featuring tridentate, meridionally chelating “pincer” ligands has stimulated the development of ligand frameworks containing multiple pincer sites. Here, the coordination chemistry of a novel pentadentate ligand (L^N3O2) that provides two closely spaced NNO pincer-type compartments fused together at a central diarylamido unit is described. The trianionic L^N3O2 chelate supports homobimetallic structures in which each M(II) ion (M = Co, Cu, Zn) is bound in a meridional fashion by the bridging diarylamido N atom and O,N-donors of the salicyaldimine arms. The metal centers are also coordinated by a mono- or bidentate …

Genetic Algorithm Optimization Of Point Charges In Force Field Development: Challenges And Insights, Maxim Vadimovich Ivanov, Marat R. Talipov, Qadir K. Timerghazin

Chemistry Faculty Research and Publications

Evolutionary methods, such as genetic algorithms (GAs), provide powerful tools for optimization of the force field parameters, especially in the case of simultaneous fitting of the force field terms against extensive reference data. However, GA fitting of the nonbonded interaction parameters that includes point charges has not been explored in the literature, likely due to numerous difficulties with even a simpler problem of the least-squares fitting of the atomic point charges against a reference molecular electrostatic potential (MEP), which often demonstrates an unusually high variation of the fitted charges on buried atoms. Here, we examine the performance of the GA …

Synthetic Studies Of Ambruticin: Preparation Of The C1-C8 Tetrahydropyran And The C17-C24 Dihydropyran Segments, Luping Liu, Julie L. Wondergem, William A. Donaldson

Chemistry Faculty Research and Publications

The C1-C8 tetrahydropyran and the C17-C24 dihdropyran segments of ambruticin were prepared from L-arabinose in 11 steps, 7.6% overall yield and from (S)-ethyl lactate in 8 steps, 22.2% overall yield respectively.

Cellulose, Chitosan, And Keratin Composite Materials. Controlled Drug Release, Chieu D. Tran, Tamutsiwa Moven Mututuvari

Chemistry Faculty Research and Publications

A method was developed in which cellulose (CEL) and/or chitosan (CS) were added to keratin (KER) to enable [CEL/CS+KER] composites to have better mechanical strength and wider utilization. Butylmethylimmidazolium chloride ([BMIm⁺Cl^–]), an ionic liquid, was used as the sole solvent, and because the [BMIm⁺Cl^–] used was recovered, the method is green and recyclable. Fourier transform infrared spectroscopy results confirm that KER, CS, and CEL remain chemically intact in the composites. Tensile strength results expectedly show that adding CEL or CS into KER substantially increases the mechanical strength of the composites. We found …

Mono-N-Acyl-2,6-Diaminopimelic Acid Derivatives: Analysis By Electromigration And Spectroscopic Methods And Examination Of Enzyme Inhibitory Activity, Jan Hlaváček, Miloslava Vítovcová, Petra Sázelová, Jan Pícha, Václav Vaněk, Miloš Buděšínský, Jiří Jiráček, Danuta M. Gillner, Richard C. Holz, Ivan Mikšík, Václav Kašička

Chemistry Faculty Research and Publications

Thirteen mono-N-acyl derivatives of 2,6-diaminopimelic acid (DAP)—new potential inhibitors of the dapE-encoded N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE; EC 3.5.1.18)—were analyzed and characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies and two capillary electromigration methods: capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC). Structural features of DAP derivatives were characterized by IR and NMR spectroscopies, whereas CZE and MEKC were applied to evaluate their purity and to investigate their electromigration properties. Effective electrophoretic mobilities of these compounds were determined by CZE in acidic and alkaline background electrolytes (BGEs) and by MEKC in acidic and alkaline BGEs …

Protein Expression, Characterization And Activity Comparisons Of Wild Type And Mutant Dusp5 Proteins, Jaladhi Nayak, Adam J. Gastonguay, Marat R. Talipov, Padmanabhan Vakeel, Elise A. Span, Kelsey S. Kalous, Raman G. Kutty, David R. Jensen, Phani Raj Pokkuluri, Daniel S. Sem, Rajendra Rathore, Ramani Ramchandran

Chemistry Faculty Research and Publications

Background

The mitogen-activated protein kinases (MAPKs) pathway is critical for cellular signaling, and proteins such as phosphatases that regulate this pathway are important for normal tissue development. Based on our previous work on dual specificity phosphatase-5 (DUSP5), and its role in embryonic vascular development and disease, we hypothesized that mutations in DUSP5 will affect its function.

Results

In this study, we tested this hypothesis by generating full-length glutathione-S-transferase-tagged DUSP5 and serine 147 proline mutant (S147P) proteins from bacteria. Light scattering analysis, circular dichroism, enzymatic assays and molecular modeling approaches have been performed to extensively characterize the protein form and function. …

Structure, Stability, And Substituent Effects In Aromatic S-Nitrosothiols: The Crucial Effect Of A Cascading Negative Hyperconjugation/Conjugation Interaction, Matthew Flister, Qadir K. Timerghazin

Chemistry Faculty Research and Publications

Aromatic S-nitrosothiols (RSNOs) are of significant interest as potential donors of nitric oxide and related biologically active molecules. Here, we address a number of poorly understood properties of these species via a detailed density functional theory and the natural bond orbital (NBO) investigation of the parent PhSNO molecule. We find that the characteristic perpendicular orientation of the −SNO group relative to the phenyl ring is determined by a combination of the steric factors and the donor–acceptor interactions including, in particular, a cascading orbital interaction involving electron delocalization from the oxygen lone pair to the σ-antibonding S–N orbital and then …

Supramolecular Biopolymeric Composite Materials: Green Synthesis, Characterization And Applications, Tamutsiwa Moven Mututuvari

Dissertations (1934 -)

Macrocycles, such as crown ethers (CRs) and resorcinarenes (RESs), exhibit selective complexation of heavy metal ions and organic pollutants respectively. Consequently, they have been investigated for their suitability in adsorbing these aqueous pollutants. However, they are difficult to handle and recycle for reuse because, by themselves, they can only be fabricated in powder form. To alleviate this challenge, we developed a method to encapsulate these macrocycles into film-forming polysaccharides--cellulose (CEL) and chitosan (CS). This was achieved by using a green and recyclable solvent, an ionic liquid, to dissolve both macrocycles and polysaccharides and regenerate corresponding composites in water. Resultant composites …

Resonant Two-Photon Ionization Studies Of Non Covalent Interactions In Halo Aromatic Clusters And Spin-Orbit Coupling Modeling In Mono-Halocarbenes, Silver Nyambo

Dissertations (1934 -)

Non-covalent interactions in halobenzenes (PhX) (X=F, Cl, Br) and phenylamine (C₆ H₅ NH₂ ) have been studied here using resonance two-photon ionization (R2PI) spectroscopy combined with a linear TOF-mass spectrometer. Their interaction with polar molecules in form of ammonia (NH ₃ ) and trifluorohalomethanes (CF₃ X) has also been studied. DFT and TD-DFT calculations using M06-2X functionals were carried out on different cluster conformations to compliment experimental results. A general trend of broadness in homogenous dimers (PhX)₂ , has been attributed to mainly the presence of multiple cluster isomers and Frank-Condon activity in the low …

Preparation Of Cyclohexenones From Acyclic (Pentadienyl)Iron(1+) Cations: Synthetic Studies Directed Toward The A-Ring Of Dihydrotachysterols, Charles Felix Manful, William A. Donaldson

Chemistry Faculty Research and Publications

The reaction of tricarbonyl(3-methylpentadienyl)iron(1+) cation (7) with stabilized carbon nucleophiles affords 4-methyl-5-substituted cyclohexenones. Reaction of 7 with sodium bis[(+)-2-phenylcyclohexyl]malonate afforded a mixture of diastereomers (de = 60 %); the diastereomeric allylic alcohols resulting from Luche reduction of this mixture were separable by column chromatography. Issues in diastereoselectivity in approaches to synthons for the A-ring of the tachysterols from these cyclohexenones are reported.

Interactive Tool For Visualization Of Adiabatic Adjustment In Aph Coordinates For Computational Studies Of Vibrational Motion And Chemical Reactions, Alexander Teplukhin, Dmitri Babikov

Chemistry Faculty Research and Publications

The adiabatically-adjusting principal-axes hyperspherical (APH) coordinates reviewed in this letter are one of the best coordinate sets developed for computational treatment of spectroscopy and dynamics of triatomic molecules. Unfortunately, it is not so easy to understand and interpret them, compared to other simpler coordinates, like valence coordinates or Jacobi coordinates. To address this issue, we developed a desktop application called APHDemo. This tool visualizes the process of adjustment of the APH coordinates to the shape of a triatomic molecule during molecular vibrations or chemical reaction, and helps to understand their physical meaning without going into complicated math.

Synthesis Of Homo- And Heterobimetallic NiIi–MIi (M = Fe, Co, Ni, Zn) Complexes Based On An Unsymmetric Ligand Framework: Structures, Spectroscopic Features, And Redox Properties, Denan Wang, Sergey V. Lindeman, Adam T. Fiedler

Chemistry Faculty Research and Publications

Several homo- and heterobimetallic Ni^II–M^II complexes (M^II = Fe, Co, Ni, Zn) supported by an unsymmetric polydentate ligand (L₁³⁻) are reported (L₁³⁻ is the trianion of 2-[bis(2-hydroxy-3,5-tert-butylphenyl)aminomethyl]-4-methyl-6-[(2-pyridylmethyl)iminomethyl]phenol). The L₁³⁻ chelate provides two distinct coordination environments: a planar tridentate {N₂O} site (A) and a tetradentate {NO₃} site (B). Reaction of L₁³⁻ with equimolar amounts of Ni^II and M^II salts provides bimetallic complexes in which the Ni^II ion exclusively occupies the tetragonal A-site and the M^II ion is found …

Chitosan-Cellulose Composite For Wound Dressing Material. Part 2. Antimicrobial Activity, Blood Absorption Ability, And Biocompatibility, April L. Harkins, Simon Duri, Luther C. Kloth, Chieu D. Tran

Clinical Lab Sciences Faculty Research and Publications

Chitosan (CS), a polysaccharide derived from chitin, the second most abundant polysaccharide, is widely used in the medical world because of its natural and nontoxic properties and its innate ability for antibacterial and hemostasis effects. In this study, the novel composites containing CS and cellulose (CEL) (i.e., [CEL + CS]), which we have previously synthesized using a green and totally recyclable method, were investigated for their antimicrobial activity, absorption of anticoagulated whole blood, anti-inflammatory activity through the reduction of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), and the biocompatibility with human fibroblasts. The [CEL + CS] composites were found to …

Synthesis, Characterization And Reactivity Studies Of Fe(Ii) Complexes With Relevance To The Radical Sam Enzymes, Xixi Hong

Master's Theses (2009 -)

It is well-established that S-adenosylmethionine (SAM) serves as the methyl group donor in methylations of DNA, hormones, neurotransmitters and signal transduction systems. However, a new class of enzymatic reactions involving SAM has recently attracted considerable attention. In these systems, SAM initiates radical-based reactions at the active sites of enzymes via formation of an adenosyl radical, which further abstracts a H-atom from the substrate to initiate a radical-based mechanism. However, modeling studies of radical SAM enzymes have been hindered, by difficulties in preparing adequate synthetic [Fe4S4] clusters. We prepared a novel series of Fe(II) complexes with tripodal tris(2-hydroxybenzyl)amine ligands, which replicate …

Investigations Of Synthetic Models Of Mononuclear Nonheme Iron Dioxygenases, Michael Bittner

Dissertations (1934 -)

Ring cleaving dioxygenases, such as o-aminophenol dioxygenase (APDO) and extradiol catechol dioxygenases (CatD), play an important role in human metabolism and the degradation of aromatic pollutants, yet questions still remain concerning the enzymatic mechanisms. One area of the catalytic cycle that remains controversial is the geometric and electronic structure of the intermediate formed after O₂ binding to the Fe(II) centers. Synthetic model systems can be useful for studying enzyme active sites, as they are easier to modify and characterize than the enzymes themselves. However, synthetic models of APDOs have been relatively rare thus far. We prepared several monoiron(II) complexes …

Electrochemistry And Spectroelectrochemistry Of 1,4-Dinitrobenzene In Acetonitrile And Room-Temperature Ionic Liquids: Ion-Pairing Effects In Mixed Solvents, Abderrahman Atifi, Michael D. Ryan

Chemistry Faculty Research and Publications

Room-temperature ionic liquids (RTILs) have been shown to have a significant effect on the redox potentials of compounds such as 1,4-dinitrobenzene (DNB), which can be reduced in two one-electron steps. The most noticeable effect is that the two one-electron waves in acetonitrile collapsed to a single two-electron wave in a RTIL such as butylmethyl imidazolium-BF₄ (BMImBF₄). In order to probe this effect over a wider range of mixed-molecular-solvent/RTIL solutions, the reduction process was studied using UV–vis spectroelectrochemistry. With the use of spectroelectrochemistry, it was possible to calculate readily the difference in E°’s between the first and …

Fluorescence2d: Software For Accelerated Acquisition And Analysis Of Two-Dimensional Fluorescence Spectra, Evgenii L. Kovrigin

Chemistry Faculty Research and Publications

The Fluorescence2D is free software that allows analysis of two-dimensional fluorescence spectra obtained using the accelerated “triangular” acquisition schemes. The software is a combination of Python and MATLAB-based programs that perform conversion of the triangular data, display of the two-dimensional spectra, extraction of 1D slices at different wavelengths, and output in various graphic formats.

In Vitro Biosynthesis And Chemical Identification Of Udp-N-Acetyl-D-Quinovosamine (Udp-D-Quinac), Tiezheng Li, Laurie Simonds, Evgenii L. Kovrigin, K. Dale Noel

Chemistry Faculty Research and Publications

N-acetyl-d-quinovosamine (2-acetamido-2,6-dideoxy-d-glucose, QuiNAc) occurs in the polysaccharide structures of many Gram-negative bacteria. In the biosynthesis of QuiNAc-containing polysaccharides, UDP-QuiNAc is the hypothetical donor of the QuiNAc residue. Biosynthesis of UDP-QuiNAc has been proposed to occur by 4,6-dehydration of UDP-N-acetyl-d-glucosamine (UDP-GlcNAc) to UDP-2-acetamido-2,6-dideoxy-d-xylo-4-hexulose followed by reduction of this 4-keto intermediate to UDP-QuiNAc. Several specific dehydratases are known to catalyze the first proposed step. A specific reductase for the last step has not been demonstrated in vitro, but previous mutant analysis suggested that Rhizobium etli gene wreQ might encode this reductase. Therefore, this gene was cloned and expressed …

The Dimerization Domain In Dape Enzymes Is Required For Catalysis, Boguslaw Nocek, Anna Starus, Magdalena Makowska-Grzyska, Blanca Gutierrez, Stephen Sanchez, Robert Jedrzejczak, Jamey C. Mack, Kenneth W. Olsen, Andzrej Joachimiak, Richard C. Holz

Chemistry Faculty Research and Publications

The emergence of antibiotic-resistant bacterial strains underscores the importance of identifying new drug targets and developing new antimicrobial compounds. Lysine and meso-diaminopimelic acid are essential for protein production and bacterial peptidoglycan cell wall remodeling and are synthesized in bacteria by enzymes encoded within dap operon. Therefore dap enzymes may serve as excellent targets for developing a new class of antimicrobial agents. The dapE-encoded N-succinyl-L,L-diaminopimelic acid desuccinylase (DapE) converts N-succinyl-L,L-diaminopimelic acid to L,Ldiaminopimelic acid and succinate. The enzyme is composed of catalytic and dimerization domains, and belongs to the M20 peptidase family. To understand the specific role …

Dioxygen Reactivity Of Biomimetic Fe(Ii) Complexes With Noninnocent Catecholate, O-Aminophenolate, And O-Phenylenediamine Ligands, Michael M. Bittner, Sergey V. Lindeman, Cordina V. Popescu, Adam T. Fiedler

Chemistry Faculty Research and Publications

This study describes the O₂ reactivity of a series of high-spin mononuclear Fe(II) complexes each containing the facially coordinating tris(4,5-diphenyl-1-methylimidazol-2-yl)phosphine (^Ph2TIP) ligand and one of the following bidentate, redox-active ligands: 4-tert-butylcatecholate (^tBuCatH^–), 4,6-di-tert-butyl-2-aminophenolate (^tBu2APH^–), or 4-tert-butyl-1,2-phenylenediamine (^tBuPDA). The preparation and X-ray structural characterization of [Fe²⁺(^Ph2TIP)(^tBuCatH)]OTf, [3]OTf and [Fe²⁺(^Ph2TIP)(^tBuPDA)](OTf)₂, [4](OTf)₂ are described here, whereas [Fe²⁺(^{Ph2 …}

Photochemical Elimination Reactions That Proceed Via Triplet Excited State Electrocyclic Ring Closures, Himali Devika Jayasekara

Master's Theses (2009 -)

Cage compounds have become an important tool for the study of biological processes. The research focuses on new cage compounds that can unmask functional groups present in biologically important molecules such as proteins, peptides, and oligonucleosides. The project focuses on certain functional groups that are often difficult to release photochemically. These are the thiolate groups present in cysteine residues of proteins and peptides. Thiolate groups are fairly basic leaving groups, unlike the more labile groups such as the carboxylates that are present in proteins and peptides, or the phosphate groups present in nucleosides. The research takes advantage of the ability …

Tcr Scanning Of Peptide/Mhc Through Complementary Matching Of Receptor And Ligand Molecular Flexibility, William F. Hawse, Soumya De, Alexander I. Greenwood, Linda K. Nicholson, Jaroslav Zajicek, Evgeni L. Kovrigin, David M. Kranz, K. Chrisopher Garcia, Brian M. Baker

Chemistry Faculty Research and Publications

Although conformational changes in TCRs and peptide Ags presented by MHC protein (pMHC) molecules often occur upon binding, their relationship to intrinsic flexibility and role in ligand selectivity are poorly understood. In this study, we used nuclear magnetic resonance to study TCR–pMHC binding, examining recognition of the QL9/H-2L^d complex by the 2C TCR. Although the majority of the CDR loops of the 2C TCR rigidify upon binding, the CDR3β loop remains mobile within the TCR–pMHC interface. Remarkably, the region of the QL9 peptide that interfaces with CDR3β is also mobile in the free pMHC and in the TCR–pMHC complex. …

Acrylamide Production Using Encapsulated Nitrile Hydratase From Pseudonocardia Thermophila In A Sol–Gel Matrix, Salette Martinez, Misty L. Kuhn, James T. Russell, Richard C. Holz, Timothy E. Elgren

Chemistry Faculty Research and Publications

The cobalt-type nitrile hydratase from Pseudonocardia thermophila JCM 3095 (PtNHase) was successfully encapsulated in tetramethyl orthosilicate sol–gel matrices to produce a PtNHase:sol–gel biomaterial. The PtNHase:sol–gel biomaterial catalyzed the conversion of 600 mM acrylonitrile to acrylamide in 60 min at 35 °C with a yields of >90%. Treatment of the biomaterial with proteases confirmed that the catalytic activity is due to the encapsulated enzyme and not surface bound NHase. The biomaterial retained 50% of its activity after being used for a total of 13 consecutive reactions for the conversion of acrylonitrile to acrylamide. The thermostability and long-term …

Synergistic Adsorption Of Heavy Metal Ions And Organic Pollutants By Supramolecular Polysaccharide Composite Materials From Cellulose, Chitosan And Crown Ether, Tamutsiwa M. Mututuvari, Chieu D. Tran

Chemistry Faculty Research and Publications

We have developed a simple one-step method to synthesize novel supramolecular polysaccharide composites from cellulose (CEL), chitosan (CS) and benzo-15-crown 5 (B15C5). Butylmethylimidazolium chloride [BMIm⁺Cl⁻], an ionic liquid (IL), was used as a sole solvent for dissolution and preparation of the composites. Since majority of [BMIm⁺Cl⁻] used was recovered for reuse, the method is recyclable. The [CEL/CS + B15C5] composites obtained retain properties of their components, namely superior mechanical strength (from CEL), excellent adsorption capability for heavy metal ions and organic pollutants (from B15C5 and CS). More importantly, the [CEL/CS + B15C5] …

Resonance Raman Spectroscopy Reveals That Substrate Structure Selectively Impacts The Heme-Bound Diatomic Ligands Of Cyp17, Piotr J. Mak, Michael C. Gregory, Stephen G. Sligar, James R. Kincaid

Chemistry Faculty Research and Publications

An important function of steroidogenic cytochromes P450 is the transformation of cholesterol to produce androgens, estrogens, and the corticosteroids. The activities of cytochrome P450c17 (CYP17) are essential in sex hormone biosynthesis, with severe developmental defects being a consequence of deficiency or mutations. The first reaction catalyzed by this multifunctional P450 is the 17α-hydroxylation of pregnenolone (PREG) to 17α-hydroxypregnenolone (17-OH PREG) and progesterone (PROG) to 17α-hydroxyprogesterone (17-OH PROG). The hydroxylated products then either are used for production of corticoids or undergo a second CYP17 catalyzed transformation, representing the first committed step of androgen formation. While the hydroxylation reactions are catalyzed by …

Spectral Data For "Probing The Human Estrogen Receptor-Alpha Binding Requirements For Phenolic Mono- And Do-Hydroxyl Compounds: A Combined Synthesis, Binding And Docking Study", Christopher Mccullough, Terrence S. Neumann, Jayapal Reddy Gone, Zhengjie He, Julie Lukesh, Rajesh K. Pandey, William A. Donaldson, Daniel S. Sem

Natural Products Synthesis via Organoiron Methodology

Spectral data used in the course of researching "Probing the human estrogen receptor-alpha binding requirements for phenolic mono- and do-hydroxyl compounds: A combined synthesis, binding and docking study".

Various estrogen analogs were synthesized and tested for binding to human ERα using a fluorescence polarization displacement assay. Binding affinity and orientation were also predicted using docking calculations. Docking was able to accurately predict relative binding affinity and orientation for estradiol, but only if a tightly bound water molecule bridging Arg394/Glu353 is present. Di-hydroxyl compounds sometimes bind in two orientations, which are flipped in terms of relative positioning of their hydroxyl groups. …

Generation Of Diverse Molecular Complexity From Cyclooctatetraene, Mohamed Fawzy El Mansy

Dissertations (1934 -)

ABSTRACT

GENERATION OF DIVERSE MOLECULAR COMPLEXITY

FROM CYCLOOCTATETRAENE

Mohamed F. El Mansy, B.Sc, M.Sc.

Marquette University, 2014

The use of simple hydrocarbons as starting materials for the synthesis of complex molecules relies on efficient methods for oxidation, functionalization or rearrangement. For example, various researchers have explored cyclopentadiene or cycloheptatriene as precursors for the preparation of a wide variety of drug candidates, natural products and synthetic products. The purpose of this research is to explore methods to transform the simple hydrocarbon, cyclooctatetraene (COT) into complex target molecules.

Tricarbonyl (cyclooctatetraene)iron, readily prepared from COT, reacts with a variety of electrophiles to form …

Isomer Dependence In The Assembly And Lability Of Silver(I) Trifluoromethanesulfonate Complexes Of The Heteroditopic Ligands, 2-, 3-, And 4-[Di(1H-Pyrazolyl)Methyl]Phenyl(Di-P-Tolyl)Phosphine, James R. Gardinier, Jeewantha S. Hewage, Sergey V. Lindeman

Chemistry Faculty Research and Publications

Three isomers of a new heteroditopic ligand that contains a di(1H-pyrazolyl)methyl (−CHpz₂) moiety connected to a di(p-tolyl)phosphine group via a para-, meta-, or ortho-phenylene spacer (pL, mL, and oL, respectively) have been synthesized by using a palladium(0)-catalyzed coupling reaction between HP(p-tolyl)₂ and the appropriate isomer of (IC₆H₄)CHpz₂. The 1:1 complexes of silver(I) trifluoromethanesulfonate, Ag(OTf), were prepared to examine the nature of ligand coordination and the type of supramolecular isomer (monomeric, cyclic oligomeric, or polymeric) that would be obtained. …

Synthesis And Spectroscopic Characterization Of High-Spin Mononuclear Iron(Ii) P-Semiquinonate Complexes, Amanda E. Baum, Heaweon Park, Sergey V. Lindeman, Adam T. Fiedler

Chemistry Faculty Research and Publications

Two mononuclear iron(II) p-semiquinonate (pSQ) complexes have been generated via one-electron reduction of precursor complexes containing a substituted 1,4-naphthoquinone ligand. Detailed spectroscopic and computational analysis confirmed the presence of a coordinated pSQ radical ferromagnetically coupled to the high-spin FeII center. The complexes are intended to model electronic interactions between (semi)quinone and iron cofactors in biology.

Enantiomeric Selective Adsorption Of Amino Acid By Polysaccharide Composite Materials, Simon Duri, Chieu D. Tran

Chemistry Faculty Research and Publications

A composite containing cellulose (CEL) and chitosan (CS) synthesized by a simple and recyclable method by using butylmethylimmidazolium chloride, an ionic liquid, was found to exhibit remarkable enantiomeric selectivity toward the adsorption of amino acids. The highest adsorption capacity and enantiomeric selectivity are exhibited by 100% CS. A racemic amino acid can be enantiomerically resolved by 100% CS in about 96–120 h. Interestingly, adsorption by 50:50 CEL/CS is more similar to that by 100% CS than to 100% CEL. Specifically, whereas 100% CEL has the lowest adsorption capacity and enantiomeric selectivity, 50:50 CEL/CS has sufficient enantiomeric selectivity to enable it …