Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

Chemistry

PDF

Western University

Series

2015

Articles 1 - 15 of 15

Full-Text Articles in Physical Sciences and Mathematics

Kohn–Sham Exchange-Correlation Potentials From Second-Order Reduced Density Matrices, Rogelio Cuevas-Saavedra, Paul W. Ayers, Viktor N. Staroverov Dec 2015

Kohn–Sham Exchange-Correlation Potentials From Second-Order Reduced Density Matrices, Rogelio Cuevas-Saavedra, Paul W. Ayers, Viktor N. Staroverov

Chemistry Publications

We describe a practical algorithm for constructing the Kohn–Sham exchange-correlation potential corresponding to a given second-order reduced density matrix. Unlike conventional Kohn–Sham inversion methods in which such potentials are extracted from ground-state electron densities, the proposed technique delivers unambiguous results in finite basis sets. The approach can also be used to separate approximately the exchange and correlation potentials for a many-electron system for which the reduced density matrix is known. The algorithm is implemented for configuration-interaction wave functions and its performance is illustrated with numerical examples.

Go to article

Group 6 Metal Pentacarbonyl Complexes Of Air-Stable Primary, Secondary, And Tertiary Ferrocenylethylphosphines, Amir Rabiee Kenaree, Ethan R. Sauvé, Paul J. Ragogna, Joe Gilroy Dec 2015

Group 6 Metal Pentacarbonyl Complexes Of Air-Stable Primary, Secondary, And Tertiary Ferrocenylethylphosphines, Amir Rabiee Kenaree, Ethan R. Sauvé, Paul J. Ragogna, Joe Gilroy

Chemistry Publications

The synthesis and characterization of a series of Group 6 metal pentacarbonyl complexes of air stable primary, secondary, and tertiary phosphines containing ferrocenylethyl substituents are reported [M(CO)5L: M = Cr, Mo, W; L = PH2(CH2CH2Fc), PH(CH2CH2Fc)2, P(CH2CH2Fc)3]. The structure and composition of the complexes were confirmed by multinuclear NMR spectroscopy, IR and UV-Vis absorption spectroscopy, mass spectrometry, X-ray crystallography, and elemental analysis. The solid-state structural data reported revealed trends in M-C and M-P bond lengths that mirrored those of the …

Go to article

Side-Chain Boron Difluoride Formazanate Polymers Via Ring-Opening Metathesis Polymerization, Samantha Novoa, Joseph A. Paquette, Stephanie M. Barbon, Ryan R. Maar, Joe Gilroy Nov 2015

Side-Chain Boron Difluoride Formazanate Polymers Via Ring-Opening Metathesis Polymerization, Samantha Novoa, Joseph A. Paquette, Stephanie M. Barbon, Ryan R. Maar, Joe Gilroy

Chemistry Publications

The synthesis, characterization, and ring-opening methathesis polymerization (ROMP) of a novel norbornene-based boron difluoride (BF2) formazante monomer are described in detail. The polymerization studies confirmed ROMP to occur in the presence of BF2 formazanates, and also demonstrated the controlled nature of the polymerization. The polymers retained many of the unique characteristics of the monomers in dichloromethane, including absorption and emission at maximum wavelengths of 518 and 645 nm, large Stoke's shifts (uST = 127 nm, 3,800 cm-1), and the ability to act as electron reservoirs to form borataverdazyl-based poly(radical anions) (E°red1 …

Go to article

An Azide-Functionalized Nitronyl Nitroxide Radical: Synthesis, Characterization And Staudinger-Bertozzi Ligation Reactivity, Stephanie M. Barbon, Pierangelo Gobbo, Wilson Luo, Jacquelyn T. Price, Mark C. Biesenger, Mark S. Workentin, Joe Gilroy Oct 2015

An Azide-Functionalized Nitronyl Nitroxide Radical: Synthesis, Characterization And Staudinger-Bertozzi Ligation Reactivity, Stephanie M. Barbon, Pierangelo Gobbo, Wilson Luo, Jacquelyn T. Price, Mark C. Biesenger, Mark S. Workentin, Joe Gilroy

Chemistry Publications

An azide-functionalized nitronyl nitroxide was successfully synthesized and its reactivity towards the Staudinger-Bertozzi ligation was explored. While a model reaction in solution showed the conversion of the nitronyl nitroxide to an imino nitroxide radical, the same reaction at the interface of gold nanoparticles allowed for successful covalent incorporation of the nitronyl nitroxide radical onto the nanoparticles.

Go to article

Oxidative Cyclization Of Tertiary Pentenol Derivatives Forming 2,5,5-Trisubstituted Thf Rings And The Total Synthesis Of Cyclocapitelline, Geoffrey A. Phillips, Cory Palmer, Andrew C. Stevens, Mattew L. Piotrowski, Daryyl Sr Dekruyf, Brian Pagenkopf Oct 2015

Oxidative Cyclization Of Tertiary Pentenol Derivatives Forming 2,5,5-Trisubstituted Thf Rings And The Total Synthesis Of Cyclocapitelline, Geoffrey A. Phillips, Cory Palmer, Andrew C. Stevens, Mattew L. Piotrowski, Daryyl Sr Dekruyf, Brian Pagenkopf

Chemistry Publications

The synthesis of 2,5,5-trisubstituted tetrahydrofuran rings was accomplished via the Mukaiyama aerobic oxidative cyclization of tertiary 5-pentenols employing the Co(nmp)2catalyst. A variety of THFs were formed in moderate to good yield and diastereoselectivity. The method developed herein was successfully applied to an enantioselective total synthesis of cyclocapitelline.

Go to article

Evaluation Of Anisole-Substituted Boron Difluoride Formazanate Complexes For Fluorescence Cell Imaging, Ryan R. Maar, Stephanie M. Barbon, Neha Sharma, Hilary Groom, Leonard G. Luyt, Joe Gilroy Sep 2015

Evaluation Of Anisole-Substituted Boron Difluoride Formazanate Complexes For Fluorescence Cell Imaging, Ryan R. Maar, Stephanie M. Barbon, Neha Sharma, Hilary Groom, Leonard G. Luyt, Joe Gilroy

Chemistry Publications

The evaluation of three subclasses of boron difluoride formazanate complexes bearing o-, m-, and p-anisole N-aryl substituents (Ar) as readily accessible alternatives to boron dipyrromethene (BODIPY) dyes for cell imaging applications is described. While the wavelengths of maximum absorption (lmax) and emission (lem) observed for each subclass of complexes, which differed by their carbon-bound substituents (R), were similar, the emission quantum yields for 7a-c (R = cyano) were enhanced relative to 8a-c (R = nitro) and 9a-c (R = phenyl). Complexes 7a-c and 8a-c were also significantly …

Go to article

Substrate-Mediated Deactivation Of A Ru(PTBu2nBn2) Cooperative Complex, John Paul J. Bow, Paul D. Boyle, Johanna M. Blacquiere Sep 2015

Substrate-Mediated Deactivation Of A Ru(PTBu2nBn2) Cooperative Complex, John Paul J. Bow, Paul D. Boyle, Johanna M. Blacquiere

Chemistry Publications

Ligand design for metal-ligand cooperative (MLC) catalysis is inherently more complex than that for traditional non-cooperative ligands. The basicity, sterics and structure of the acid/base group in MLC proton-transfer (PT) complexes, for instance, undoubtedly influence catalyst performance. Herein, we evaluate the highly tunable PR2NR′2 (1,5-R′-3,7-R-1,5-diaza-3,7-diphosphacyclooctane) ligand family for the first time in an organic transformation. With [Ru(Cp)(PtBu2NBn2)(MeCN)][PF6] as the catalyst, no turnover was observed in the anti-Markovnikov hydration of alkynes, a known PT MLC reaction. Treatment of the cooperative complex with phenylacetylene affords a vinylammonium product in which the pendant nitrogen atom of the PtBu2NBn2 ligand forms a Lewis acid-base …

Go to article

Synthesis And Characterization Of A Family Of Air-Stable Ferrocene- And Ruthenocene-Containing Primary, Secondary, And Tertiary Phosphines, Amir Rabiee Kenaree, Tyler J. Cuthbert, Stephanie M. Barbon, Paul D. Boyle, Elizabeth R. Gillies, Paul J. Ragogna, Joe Gilroy Aug 2015

Synthesis And Characterization Of A Family Of Air-Stable Ferrocene- And Ruthenocene-Containing Primary, Secondary, And Tertiary Phosphines, Amir Rabiee Kenaree, Tyler J. Cuthbert, Stephanie M. Barbon, Paul D. Boyle, Elizabeth R. Gillies, Paul J. Ragogna, Joe Gilroy

Chemistry Publications

The synthesis and characterization of a family of air-stable primary, secondary, and tertiary phosphines containing all possible combinations of ethylferrocene and ethylruthenocene substituents are reported. Each phosphine was characterized by 1H, 13C, and 31P NMR spectroscopy, IR and UV-vis absorption spectroscopy, mass spectrometry, and elemental analysis. With the exception of primary ethylruthenocene phosphine 8a, all of the title compounds have been studied by single crystal X-ray crystallography. Ferrocene-containing phosphines showed maximum absorption at wavelengths of ca. 440 nm and qualitatively reversible oxidation waves in their cyclic voltammograms with intensities scaling to the number of ferrocene units …

Go to article

Enhanced Rates Of Photoinduced Molecular Orientation In A Series Of Molecular Glassy Thin Films., Kristen E Snell, Renjie Hou, Eléna Ishow, François Lagugné-Labarthet Jul 2015

Enhanced Rates Of Photoinduced Molecular Orientation In A Series Of Molecular Glassy Thin Films., Kristen E Snell, Renjie Hou, Eléna Ishow, François Lagugné-Labarthet

Chemistry Publications

Photoinduced orientation in a series of molecular glasses made of small push-pull azo derivatives is dynamically investigated for the first time. Birefringence measurements at 632.8 nm are conducted with a temporal resolution of 100 ms to probe the fast rate of the azo orientation induced under polarized light and its temporal stability over several consecutive cycles. To better evaluate the influence of the azo chemical substituents and their electronic properties on the orientation of the whole molecule, a series of push-pull azo derivatives involving a triphenylaminoazo core substituted with distinct electron-withdrawing moieties is studied. All resulting thin films are probed …

Go to article

Synthesis And Characterization Of Conjugated/Cross-Conjugated Benzene-Bridged Boron Difluoride Formazanate Dimers, Stephanie M. Barbon, Jacquelyn T. Price, Umesh Yogarajah, Joe Gilroy Jun 2015

Synthesis And Characterization Of Conjugated/Cross-Conjugated Benzene-Bridged Boron Difluoride Formazanate Dimers, Stephanie M. Barbon, Jacquelyn T. Price, Umesh Yogarajah, Joe Gilroy

Chemistry Publications

One of the most common strategies for the production of molecular materials with optical properties in the far-red/near-IR regions of the electromagnetic spectrum is their incorporation into dimeric architectures. In this paper, we describe the synthesis and characterization (1H, 11B, 13C and 19F NMR spectroscopy, IR and UV-Vis absorption and emission spectroscopy, mass spectrometry and X-ray crystallography) of the first examples of boron difluoride (BF2) formazanate dimers. Specifically, the properties of meta- and para-substituted benzene-bridged dimers p-10 and m-10 were compared to closely related boron difluoride triphenyl formazanate complex …

Go to article

Synthesis Of Tetrahydro-1,2-Oxazines And Pyrrolidines Via Cycloadditions Of Donor-Acceptor Cyclobutanes And Nitrosoarenes, Naresh Vemula, Brian L Pagenkopf Jun 2015

Synthesis Of Tetrahydro-1,2-Oxazines And Pyrrolidines Via Cycloadditions Of Donor-Acceptor Cyclobutanes And Nitrosoarenes, Naresh Vemula, Brian L Pagenkopf

Chemistry Publications

During efforts to expand the scope of Lewis-acid-catalyzed [4+2] cycloaddition between donor–acceptor cyclobutanes and nitrosoarenes, an unexpected formation of pyrrolidine products was discovered when 50 mol-% of MgI2 was used as a Lewis acid. It was also observed that the electronics of the nitrosoarene and judicious selection of the Lewis acid catalyst have a profound effect on the regioselectivity of the reaction.

Go to article

The Effect Of Extended Π-Conjugation On The Spectroscopic And Electrochemical Properties Of Boron Difluoride Formazanate Complexes, Stephanie M. Barbon, Viktor N. Staroverov, Joe Gilroy May 2015

The Effect Of Extended Π-Conjugation On The Spectroscopic And Electrochemical Properties Of Boron Difluoride Formazanate Complexes, Stephanie M. Barbon, Viktor N. Staroverov, Joe Gilroy

Chemistry Publications

The effect of extended π-conjugation on the spectroscopic and electrochemical properties of boron difluoride (BF2) formazanate complexes was studied by the systematic comparison of phenyl- and naphthyl-substituted derivatives. Each of the BF2 complexes described was characterized by 1H, 13C, 11B and 19F NMR spectroscopy, cyclic voltammetry, infrared spectroscopy, UV-vis absorption and emission spectroscopy and mass spectrometry. X-ray crystallography and electronic structure calculations were used to rationalize the trends observed, including direct comparison of 3-cyano-, 3-nitro- and 3-phenyl-substituted BF2 formazanate complexes. In all cases, the wavelength of maximum absorption and emission were red-shifted …

Go to article

Au Nanostructured Surfaces For Electrochemical And Localized Surface Plasmon Resonance-Based Monitoring Of Α-Synuclein-Small Molecule Interactions., Xin R Cheng, Gregory Q Wallace, François Lagugné-Labarthet, Kagan Kerman Feb 2015

Au Nanostructured Surfaces For Electrochemical And Localized Surface Plasmon Resonance-Based Monitoring Of Α-Synuclein-Small Molecule Interactions., Xin R Cheng, Gregory Q Wallace, François Lagugné-Labarthet, Kagan Kerman

Chemistry Publications

In this proof-of-concept study, the fabrication of novel Au nanostructured indium tin oxide (Au-ITO) surfaces is described for the development of a dual-detection platform with electrochemical and localized surface plasmon resonance (LSPR)-based biosensing capabilities. Nanosphere lithography (NSL) was applied to fabricate Au-ITO surfaces. Oligomers of α-synuclein (αS) were covalently immobilized to determine the electrochemical and LSPR characteristics of the protein. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were performed using the redox probe [Fe(CN)6](3-/4-) to detect the binding of Cu(II) ions and (-)-epigallocatechin-3-gallate (EGCG) to αS on the Au-ITO surface. Electrochemical and LSPR data were complemented by Thioflavin-T (ThT) …

Go to article

Au Nanostructured Surfaces For Electrochemical And Localized Surface Plasmon Resonance-Based Monitoring Of Α-Synuclein-Small Molecule Interactions., Xin R Cheng, Gregory Q Wallace, François Lagugné-Labarthet, Kagan Kerman Feb 2015

Au Nanostructured Surfaces For Electrochemical And Localized Surface Plasmon Resonance-Based Monitoring Of Α-Synuclein-Small Molecule Interactions., Xin R Cheng, Gregory Q Wallace, François Lagugné-Labarthet, Kagan Kerman

Chemistry Publications

In this proof-of-concept study, the fabrication of novel Au nanostructured indium tin oxide (Au-ITO) surfaces is described for the development of a dual-detection platform with electrochemical and localized surface plasmon resonance (LSPR)-based biosensing capabilities. Nanosphere lithography (NSL) was applied to fabricate Au-ITO surfaces. Oligomers of α-synuclein (αS) were covalently immobilized to determine the electrochemical and LSPR characteristics of the protein. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were performed using the redox probe [Fe(CN)6](3-/4-) to detect the binding of Cu(II) ions and (-)-epigallocatechin-3-gallate (EGCG) to αS on the Au-ITO surface. Electrochemical and LSPR data were complemented by Thioflavin-T (ThT) …

Go to article

Tunable 3d Plasmonic Cavity Nanosensors For Surface-Enhanced Raman Spectroscopy With Sub Femtomolar Limit Of Detection, Mohammadali Tabatabei, Mohamadreza Najiminaini, Kiefer Davieau, Bozena Kaminska, Mahi Singh, Jeff Carson, Francois Lagugne-Labarthet Jan 2015

Tunable 3d Plasmonic Cavity Nanosensors For Surface-Enhanced Raman Spectroscopy With Sub Femtomolar Limit Of Detection, Mohammadali Tabatabei, Mohamadreza Najiminaini, Kiefer Davieau, Bozena Kaminska, Mahi Singh, Jeff Carson, Francois Lagugne-Labarthet

Chemistry Publications

Metallic nanohole arrays (NHAs) with a high hole density have emerged with potential applications for surface-enhanced Raman spectroscopy (SERS) including the detection of analytes at ultra-low concentrations. However, these NHA structures generally yield weak localized surface plasmon resonance (LSPR) which is a prerequisite for SERS measurements. In this work, a compact three-dimensional (3D) tunable plasmonic cavity with extraordinary optical transmission properties serves as a molecular sensor with sub-femtomolar detection. The 3D nanosensor consists of a gold film containing a NHA with an underlying cavity and a gold nanocone array at the bottom of the cavity. These nanosensors provide remarkable surface …

Go to article