Physical Sciences and Mathematics Commons^™

Unveiling The Crucial Intermediates In Androgen Production, Piotr J. Mak, Michael C. Gregory, Ilia G. Denisov, Stephen G. Sligar, James R. Kincaid

Chemistry Faculty Research and Publications

Significance: The human enzyme cytochrome P450 17A1 (CYP17A1) catalyzes the critical step in the biosynthesis of the male sex hormones, and, as such, it is a key target for the inhibition of testosterone production that is necessary for the progression of certain cancers. CYP17A1 catalyzes two distinct types of chemical transformations. The first is the hydroxylation of the steroid precursors pregnenolone and progesterone. The second is a different reaction involving carbon–carbon (C-C) bond cleavage, the mechanism of which has been actively debated in the literature. Using a combination of chemical and biophysical methods, we have been able to trap and …

A Circle Has No End: Role Of Cyclic Topology And Accompanying Structural Reorganization On The Hole Distribution In Cyclic And Linear Poly‑P‑Phenylene Molecular Wires, Marat R. Talipov, Ramesh Jasti, Rajendra Rathore

Chemistry Faculty Research and Publications

π-Conjugated organic oligomers/polymers hold great promise as long-range charge-transfer materials for modern photovoltaic applications. However, a set of criteria for the rational design of functional materials is not yet available, in part because of a lack of understanding of charge distribution in extended π-conjugated systems of different topologies, and concomitant effects on redox and optical properties. Herein we demonstrate the role of cyclic versus linear topology in controlling the redox/optical properties and hole distribution in poly-p-phenylenes (PPs) with the aid of experiment, computation, and our recently developed multistate parabolic model (MPM). It is unequivocally shown that the hole …

Direct Observation Of Photoinduced Charge Separation In Ruthenium Complex/Ni(Oh)2 Nanoparticle Hybrid, Yu Tang, Brian Pattengale, John Ludwig, Abderrahman Atifi, Alexander V. Zinovev, Bin Dong, Qingyu Kong, Xiaobing Zuo, Xiaoyi Zhang, Jier Huang

Chemistry Faculty Research and Publications

Ni(OH)₂ have emerged as important functional materials for solar fuel conversion because of their potential as cost-effective bifunctional catalysts for both hydrogen and oxygen evolution reactions. However, their roles as photocatalysts in the photoinduced charge separation (CS) reactions remain unexplored. In this paper, we investigate the CS dynamics of a newly designed hybrid catalyst by integrating a Ru complex with Ni(OH)₂ nanoparticles (NPs). Using time resolved X-ray absorption spectroscopy (XTA), we directly observed the formation of the reduced Ni metal site (~60 ps), unambiguously demonstrating CS process in the hybrid through ultrafast electron transfer from Ru complex to …

Spectroscopic Evidence Of Nanodomains In Thf/Rtil Mixtures: Spectroelectrochemical And Voltammetric Study Of Nickel Porphyrins, Abderrahman Atifi, Michael D. Ryan

Chemistry Faculty Research and Publications

The presence and effect of RTIL nanodomains in molecular solvent/RTIL mixture were investigated by studying the spectroelectrochemistry and voltammetry of nickel octaethylporphyrin (Ni(OEP)) and nickel octaethylporphinone (Ni(OEPone)). Two oxidation and 2–3 reduction redox couples were observed, and the UV–visible spectra of all stable products in THF and RTIL mixtures were obtained. The E° values for the reduction couples that were studied were linearly correlated with the Gutmann acceptor number, as well as the difference in the E° values between the first two waves (ΔE₁₂° = |E₁° – E₂°|). The Δ …

The Homo Nodal Arrangement In Polychromophoric Molecules And Assemblies Controls The Interchromophoric Electronic Coupling, Marat R. Talipov, Tushar Navale, Rajendra Rathore

Chemistry Faculty Research and Publications

Triptycenes spontaneously assemble into two-dimensional networks in which long-range charge transport is facilitated by the extensive electronic coupling through the triptycene framework (intramolecularly) and by cofacial π-stacking (intermolecularly). While designing and synthesizing next-generation triptycenes containing polyaromatic chromophores, the electronic coupling amongst the chromophores was observed to be highly dependent on the nature and position of the substituents. Herein, we demonstrate using hexaalkoxytriptycenes that the electronic coupling amongst the chromophores is switched on and off by a simple repositioning of the substituents, which alters the nodal arrangement of the HOMOs of the individual chromophores. A visual inspection of the HOMOs can …

A Deeper Insight Into Strain For The Sila-Bi[6]Prismane (Si18H12) Cluster With Its Endohedrally Trapped Silicon Atom, Si19H12, Vach Holger, Lena V. Ivanova, Qadir K. Timerghazin, Fatme Jardali, Ha-Linh Thi Le

Chemistry Faculty Research and Publications

A new family of over-coordinated hydrogenated silicon nanoclusters with outstanding optical and mechanical properties has recently been proposed. For one member of this family, namely the highly symmetric Si₁₉H₁₂ nanocrystal, strain calculations have been presented with the goal to question its thermal stability and the underlying mechanism of ultrastability and electron-deficiency aromaticity. Here, the invalidity of these strain energy (SE) calculations is demonstrated mainly based on a fundamentally wrong usage of homodesmotic reactions, the miscounting of atomic bonds, and arithmetic errors. Since the article in question is entirely anchored on those erroneous SE values, all of its …

An Analytical Method For Detecting Toxic Metal Cations Using Cyclotriveratrylene Derivative Capped Gold Nanoparticles, Zachary R. Osner, Richard C. Holz, Daniel P. Becker

Chemistry Faculty Research and Publications

Cyclotriveratrylene-oxime (CTV-oxime) derivatives that terminate with a dithiolate linker were synthesized enabling the supramolecular scaffold to adhere to gold nanoparticles (AuNPs) with the bowl-shaped cavity of the CTV scaffold exposed for utilization in host–guest chemistry. Exposure of these CTV functionalized AuNPs to varying concentrations of di- and trivalent metal cations resulted in the formation of large CTV-AuNP polymeric clusters and an accompanying a shift in the plasmon resonance. These interactions between the CTV-AuNPs and the metal cations in solution provides proof-of-concept that supramolecular functionalized AuNPs can be used as a simple and straightforward, on-site detection system for toxic metal cations …

The Ras G Domain Lacks The Intrinsic Propensity To Form Dimers, Elizaveta A. Kovrigina, Azamat R. Galiakhmetov, Evgueni Kovriguine

Chemistry Faculty Research and Publications

Ras GTPase is a molecular switch controlling a number of cellular pathways including growth, proliferation, differentiation, and apoptosis. Recent reports indicated that Ras undergoes dimerization at the membrane surface through protein-protein interactions. If firmly established this property of Ras would require profound reassessment of a large amount of published data and modification of the Ras signaling paradigm. One proposed mechanism of dimerization involves formation of salt bridges between the two GTPase domains (G domains) leading to formation of a compact dimer as observed in Ras crystal structures. In this work, we interrogated the intrinsic ability of Ras to self-associate in …

Does Koopmans' Paradigm For 1-Electron Oxidation Always Hold? Breakdown Of Ip/Eox Relationship For P-Hydroquinone Ethers And The Role Of Methoxy Group Rotation, Marat R. Talipov, Anitha Boddeda, Sergey Lindeman, Rajendra Rathore

Chemistry Faculty Research and Publications

Koopmans’ paradigm states that electron loss occurs from HOMO, thus forming the basis for the observed linear relationships between HOMO/IP, HOMO/E_ox, and IP/E_ox. In cases where a molecule undergoes dramatic structural reorganization upon 1-electron oxidation, the IP/E_ox relationship does not hold, and the origin of which is not understood. For example, X-ray crystallography of the neutral and cation radicals of bicyclo[2.2.1]heptane-annulated p-hydroquinone ethers (^THE and ^MHE) showed that they undergo electron-transfer-induced conformational reorganization and show breakdown of the IP/E_ox relationship. DFT calculations revealed that Koopmans’ …

Identification Of Inhibitors That Target Dual-Specificity Phosphatase 5 Provide New Insights Into The Binding Requirements For The Two Phosphate Pockets, Terrence S. Neumann, Elise A. Span, Kelsey S. Kalous, Robert D. Bongard, Adam Gastonguay, Michael A. Lepley, Raman G. Kutty, Jaladhi Nayak, Chris Bohl, Rachel G. Lange, Majher I. Sarker, Marat R. Talipov, Rajendra Rathore, Ramani Ramchandran, Daniel S. Sem

Chemistry Faculty Research and Publications

Background: Dual-specificity phosphatase-5 (DUSP5) plays a central role in vascular development and disease. We present a p-nitrophenol phosphate (pNPP) based enzymatic assay to screen for inhibitors of the phosphatase domain of DUSP5.

Methods: pNPP is a mimic of the phosphorylated tyrosine on the ERK2 substrate (pERK2) and binds the DUSP5 phosphatase domain with a Km of 7.6 ± 0.4 mM. Docking followed by inhibitor verification using the pNPP assay identified a series of polysulfonated aromatic inhibitors that occupy the DUSP5 active site in the region that is likely occupied by the dual-phosphorylated ERK2 substrate tripeptide (pThr-Glu-pTyr). Secondary assays …

Di- And Trinuclear Mixed-Valence Copper Amidinate Complexes From Reduction Of Iodine, Andrew C. Lane, Charles L. Barnes, William E. Antholine, Denan Wang, Adam T. Fiedler, Justin R. Walensky

Chemistry Faculty Research and Publications

Molecular examples of mixed-valence copper complexes through chemical oxidation are rare but invoked in the mechanism of substrate activation, especially oxygen, in copper-containing enzymes. To examine the cooperative chemistry between two metals in close proximity to each other we began studying the reactivity of a dinuclear Cu(I) amidinate complex. The reaction of [(2,6-Me2C6H3N)2C(H)]2Cu2, 1, with I2 in tetrahydrofuran (THF), CH3CN, and toluene affords three new mixed-valence copper complexes [(2,6-Me2C6H3N)2C(H)]2Cu2(μ2-I3)(THF)2, 2, [(2,6-Me2C6H3N)2C(H)]2Cu2(μ2-I) (NCMe)2, 3, and [(2,6-Me2C6H3N)2C(H)]3Cu3(μ3-I)2, 4, respectively. The first two compounds were characterized by UV-vis and electron paramagnetic resonance spectroscopies, and their molecular structure was determined by X-ray crystallography. Both …

Scope And Mechanistic Analysis For Chemoselective Hydrogenolysis Of Carbonyl Compounds Catalyzed By A Cationic Ruthenium Hydride Complex With A Tunable Phenol Ligand, Nishantha Kumara Kalutharage, Chae S. Yi

Chemistry Faculty Research and Publications

A cationic ruthenium hydride complex, [(C₆H₆)(PCy₃)(CO)RuH]⁺BF₄^– (1), with a phenol ligand was found to exhibit high catalytic activity for the hydrogenolysis of carbonyl compounds to yield the corresponding aliphatic products. The catalytic method showed exceptionally high chemoselectivity toward the carbonyl reduction over alkene hydrogenation. Kinetic and spectroscopic studies revealed a strong electronic influence of the phenol ligand on the catalyst activity. The Hammett plot of the hydrogenolysis of 4-methoxyacetophenone displayed two opposite linear slopes for the catalytic system 1/p-X-C₆H₄OH (ρ = …

Generation Of Molecular Complexity From Cyclooctatetraene: Preparation Of Aminobicyclo[5.1.0]Octitols, Mohamed F. El-Mansy, Matthew Flister, Sergey Lindeman, Kelsey S. Kalous, Daniel S. Sem, William Donaldson

Chemistry Faculty Research and Publications

A series of eight stereoisomeric N-(tetrahydroxy bicyclo-[5.1.0]oct-2S*-yl)phthalimides were prepared in one to four steps from N-(bicyclo[5.1.0]octa-3,5-dien-2-yl)phthalimide (±)-7, which is readily available from cyclooctatetraene (62 % yield). The structural assignments of the stereoisomers were established by ¹H NMR spectral data as well as X-ray crystal structures for certain members. The outcomes of several epoxydiol hydrolyses, particularly ring contraction and enlargement, are of note. The isomeric phthalimides as well as the free amines did not exhibit β-glucosidase inhibitory activity at a concentration of less than 100 μM.

Crystal Structure Of Cis-2-(2-Carboxycyclopropyl)-Glycine (Ccg-Iii) Monohydrate, Sergey V. Lindeman, Nathaniel J. Wallock, William A. Donaldson

Chemistry Faculty Research and Publications

The title compound, C₆H₉NO₄·H₂O [systematic name: (αR,1R,2S)-rel-α-amino-2-carb­oxy­cyclo­propane­acetic acid monohydrate], crystallizes with two organic mol­ecules and two water mol­ecules in the asymmetric unit. The space group is P2₁ and the organic mol­ecules are enanti­omers, thus this is an example of a `false conglomerate' with two mol­ecules of opposite handedness in the asymmetric unit (r.m.s. overlay fit = 0.056 Å for one mol­ecule and its inverted partner). Each mol­ecule exists as a zwitterion, with proton transfer from the amino acid carb­oxy­lic acid group to …

Towards A Global Model Of Spin-Orbit Coupling In The Halocarbenes, Silver Nyambo, Cyrus Karshenas, Scott Reid, Phalgun Lolur, Richard Dawes

Chemistry Faculty Research and Publications

We report a global analysis of spin-orbit coupling in the mono-halocarbenes, CH(D)X, where X = Cl, Br, and I. These are model systems for examining carbene singlet-triplet energy gaps and spin-orbit coupling. Over the past decade, rich data sets collected using single vibronic level emission spectroscopy and stimulated emission pumping spectroscopy have yielded much information on the ground vibrational level structure and clearly demonstrated the presence of perturbations involving the low-lying triplet state. To model these interactions globally, we compare two approaches. First, we employ a diabatic treatment of the spin-orbit coupling, where the coupling matrix elements are written in …

Analyzing The Catalytic Role Of Active Site Residues In The Fe-Type Nitrile Hydratase From Comamonas Testosteroni Ni1, Salette Martinez, Rui Wu, Karoline Krzywda, Veronika Opalka, Hei Chan, Dali Liu, Richard C. Holz

Chemistry Faculty Research and Publications

A strictly conserved active site arginine residue (αR157) and two histidine residues (αH80 and αH81) located near the active site of the Fe-type nitrile hydratase from Comamonas testosteroni Ni1 (CtNHase), were mutated. These mutant enzymes were examined for their ability to bind iron and hydrate acrylonitrile. For the αR157A mutant, the residual activity (k_cat = 10 ± 2 s⁻¹) accounts for less than 1 % of the wild-type activity (k_cat = 1100 ± 30 s⁻¹) while the K_m value is nearly unchanged at 205 ± 10 mM. On the …

Discovery Of Bisamide-Heterocycles As Inhibitors Of Scavenger Receptor Bi (Sr-Bi)-Mediated Lipid Uptake, Chris Dockendorff, Patrick W. Faloon, Andrew Germain, Miao Yu, Willmen Youngsaye, Partha P. Nag, Melissa Bennion, Marsha Penman, Thomas J.F. Nieland, Sivaraman Dandapani, José R. Perez, Benito Munoz, Michelle A. Palmer, Stuart L. Schreiber, Monty Krieger

Chemistry Faculty Research and Publications

A new series of potent inhibitors of cellular lipid uptake from HDL particles mediated by scavenger receptor, class B, type I (SR-BI) was identified. The series was identified via a high-throughput screen of the National Institutes of Health Molecular Libraries Small Molecule Repository (NIH MLSMR) that measured the transfer of the fluorescent lipid DiI from HDL particles to CHO cells overexpressing SR-BI. The series is characterized by a linear peptidomimetic scaffold with two adjacent amide groups, as well as an aryl-substituted heterocycle. Analogs of the initial hit were rapidly prepared via Ugi 4-component reaction, and select enantiopure compounds were prepared …

Mixed Quantum/Classical Approach For Description Of Molecular Collisions In Astrophysical Environments, Alexander Semenov, Dmitri Babikov

Chemistry Faculty Research and Publications

An efficient and accurate mixed quantum/classical theory approach for computational treatment of inelastic scattering is extended to describe collision of an atom with a general asymmetric-top rotor polyatomic molecule. Quantum mechanics, employed to describe transitions between the internal states of the molecule, and classical mechanics, employed for description of scattering of the atom, are used in a self-consistent manner. Such calculations for rotational excitation of HCOOCH₃ in collisions with He produce accurate results at scattering energies above 15 cm^–1, although resonances near threshold, below 5 cm^–1, cannot be reproduced. Importantly, the method remains computationally affordable …

Benzo-Fused Lactams From A Diversity-Oriented Synthesis (Dos) Library As Inhibitors Of Scavenger Receptor Bi (Sr-Bi)-Mediated Lipid Uptake, Chris Dockendorff, Patrick W. Faloon, Jun Pu, Miao Yu, Stephen Johnston, Melissa Bennion, Marsha Penman, Thomas J.F. Nieland, Sivaraman Dandapani, José R. Perez, Benito Munoz, Michelle A. Palmer, Stuart L. Schreiber, Monty Krieger

Chemistry Faculty Research and Publications

We report a new series of 8-membered benzo-fused lactams that inhibit cellular lipid uptake from HDL particles mediated by Scavenger Receptor, Class B, Type I (SR-BI). The series was identified via a high-throughput screen of the National Institutes of Health Molecular Libraries Small Molecule Repository (NIH MLSMR), measuring the transfer of the fluorescent lipid DiI from HDL particles to CHO cells overexpressing SR-BI. The series is part of a previously reported diversity-oriented synthesis (DOS) library prepared via a build-couple-pair approach. Detailed structure–activity relationship (SAR) studies were performed with a selection of the original library, as well as additional analogs prepared …

Visible And Infrared Spectroelectrochemistry Of Zinc And Manganese Porphinones: Metal Vs. Porphyrin Reduction, Florentina Tutunea, Abderrahman Atifi, Michael D. Ryan

Chemistry Faculty Research and Publications

The visible and infrared spectroelectrochemistry of zinc and manganese porphinones and porphinediones was carried out in THF solutions. The aim of this work was to use FTIR spectroelectrochemistry and DFT calculation to determine whether the reduction was centered predominantly on the metal or the macrocycle. For zinc(II), the first one-electron reduction must occur on the macrocyclic ring because the metal’s d-orbitals are filled (d¹⁰). The carbonyl bands on the macrocyclic ring were used to probe the electronic structure because they can be readily observed in the infrared spectra. The results of this study are complementary to previous spectroelectrochemical …

Revisiting The Renner–Teller Effect In The X ̃2Π State Of Ccn: Pulsed Discharge-Supersonic Jet Single Vibronic Level Emission Spectroscopy, Lloyd Godfrey Muzangwa, Scott Reid

Chemistry Faculty Research and Publications

The CCN radical is a prototypical system for study of the Renner–Teller effect in its degenerate X ̃²Π ground state, with a number of experimental and theoretical studies carried out over the past 50 years. Most experimental studies have focused on the low-lying vibrational structure as observed in the high-resolution spectra of hot bands, or in emission. In this work, we have used pulsed-discharge supersonic-jet single vibronic level (SVL) emission spectroscopy from selected levels of the Ã²Δ state to probe the vibronic structure of X ̃²Π up to ∼6000 cm⁻¹ above the …

Parmodulins Inhibit Thrombus Formation Without Inducing Endothelial Injury Caused By Vorapaxar, Omozuanvbo Aisiku, Christian G. Peters, Karen De Ceunynck, Chandra C. Ghosh, James R. Dilks, Susanna F. Fustolo-Gunnink, Mingdong Huang, Chris Dockendorff, Samir M. Parikh, Robert Flaumenhaft

Chemistry Faculty Research and Publications

Protease-activated receptor-1 (PAR1) couples the coagulation cascade to platelet activation during myocardial infarction and to endothelial inflammation during sepsis. This receptor demonstrates marked signaling bias. Its activation by thrombin stimulates prothrombotic and proinflammatory signaling, whereas its activation by activated protein C (APC) stimulates cytoprotective and antiinflammatory signaling. A challenge in developing PAR1-targeted therapies is to inhibit detrimental signaling while sparing beneficial pathways. We now characterize a novel class of structurally unrelated small-molecule PAR1 antagonists, termed parmodulins, and compare the activity of these compounds to previously characterized compounds that act at the PAR1 ligand–binding site. We find that parmodulins target …

Synthesis Of 2-Acylphenol And Flavene Derivatives From The Ruthenium-Catalyzed Oxidative C-H Acylation Of Phenols With Aldehydes, Hanbin Lee, Chae S. Yi

Chemistry Faculty Research and Publications

The cationic ruthenium hydride complex [(C₆H₆)(PCy₃)(CO)RuH]⁺BF₄⁻ has been found to be an effective catalyst for the oxidative C–H coupling reaction of phenols with aldehydes to give 2-acylphenol compounds. The coupling of phenols with α,β-unsaturated aldehydes selectively gives the flavene derivatives. The catalytic method mediates direct oxidative C–H coupling of phenol and aldehyde substrates without using any metal oxidants or forming wasteful byproducts.

Aesthetics In Action: Arts In A Democratic Society: Les Aspin Center For Government, Curtis L. Carter

Chemistry Faculty Research and Publications

No abstract provided.

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 …

Electrostatic Point Charge Fitting As An Inverse Problem: Revealing The Underlying Ill-Conditioning, Maxim Vadimovich Ivanov, Marat R. Talipov, Qadir K. Timerghazin

Chemistry Faculty Research and Publications

Atom-centered point charge (PC) model of the molecular electrostatics-a major workhorse of the atomistic biomolecular simulations-is usually parameterized by least-squares (LS) fitting of the point charge values to a reference electrostatic potential, a procedure that suffers from numerical instabilities due to the ill-conditioned nature of the LS problem. To reveal the origins of this ill-conditioning, we start with a general treatment of the point charge fitting problem as an inverse problem and construct an analytical model with the point charges spherically arranged according to Lebedev quadrature which is naturally suited for the inverse electrostatic problem. This analytical model is contrasted …

Indolinyl-Thiazole Based Inhibitors Of Scavenger Receptor-Bi (Sr-Bi)-Mediated Lipid Transport, Chris Dockendorff, Patrick W. Faloon, Miao Yu, Willmen Youngsaye, Marsha Penman, Thomas J.F. Nieland, Partha P. Nag, Timothy A. Lewis, Jun Pu, Melissa Bennion, Joseph Negri, Conor Paterson, Garrett Lam, Sivaraman Dandapani, José R. Perez, Benito Munoz, Michelle A. Palmer, Stuart L. Schreiber, Monty Krieger

Chemistry Faculty Research and Publications

A potent class of indolinyl-thiazole based inhibitors of cellular lipid uptake mediated by scavenger receptor, class B, type I (SR-BI) was identified via a high-throughput screen of the National Institutes of Health Molecular Libraries Small Molecule Repository (NIH MLSMR) in an assay measuring the uptake of the fluorescent lipid DiI from HDL particles. This class of compounds is represented by ML278 (17–11), a potent (average IC₅₀ = 6 nM) and reversible inhibitor of lipid uptake via SR-BI. ML278 is a plasma-stable, noncytotoxic probe that exhibits moderate metabolic stability, thus displaying improved properties for in vitro …

Chemoselective Formation Of Unsymmetrically Substituted Ethers From Catalytic Reductive Coupling Of Aldehydes And Ketones With Alcohols In Aqueous Solution, Nishantha Kumara Kalutharage, Chae S. Yi

Chemistry Faculty Research and Publications

A well-defined cationic Ru–H complex catalyzes reductive etherification of aldehydes and ketones with alcohols. The catalytic method employs environmentally benign water as the solvent and cheaply available molecular hydrogen as the reducing agent to afford unsymmetrical ethers in a highly chemoselective manner.

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.

Bimetallic Complexes Supported By A Redox-Active Ligand With Fused Pincer-Type Coordination Sites, Denan Wang, Sergey 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 …