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- Stimuli-responsive (3)
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Articles 1 - 16 of 16
Full-Text Articles in Physical Sciences and Mathematics
End-Capping Strategies For Triggering End-To-End Depolymerization Of Polyglyoxylates, Bo Fan, John Trant, Elizabeth Gillies
End-Capping Strategies For Triggering End-To-End Depolymerization Of Polyglyoxylates, Bo Fan, John Trant, Elizabeth Gillies
Chemistry Publications
Polymers that undergo end-to-end depolymerization in response to the cleavage of a stimuli-responsive end-cap are promising for diverse applications from drug delivery to responsive coatings and plastics. It is critical that the end-cap is designed to respond to an appropriate stimulus for the application. In the current work, end-caps for triggering the depolymerization of poly(ethyl glyoxylate) (PEtG) were explored. First, a phenylboronate, a disulfi de, and an azobenzene were utilized to impart redox-responsive properties to PEtG. Then, methoxy-substituted trityl groups were used to provide sensitivity to mild acid. A multiresponsive platform was also introduced, allowing PEtG to respond to multiple …
Post-Polymerization Functionalization Of Poly (Ethylene Oxide)–Poly (Β-6-Heptenolactone) Diblock Copolymers To Tune Properties And Self-Assembly, Elizabeth Gillies, Brooke M. Raycraft, Jarret Macdonald
Post-Polymerization Functionalization Of Poly (Ethylene Oxide)–Poly (Β-6-Heptenolactone) Diblock Copolymers To Tune Properties And Self-Assembly, Elizabeth Gillies, Brooke M. Raycraft, Jarret Macdonald
Chemistry Publications
Polyester-based amphiphilic block copolymers and their nanoassemblies are of significant interest for a wide range of applications due to the degradability of the polyester block. However, the commonly used polyesters lack functional groups on their backbones, limiting the possibilities to chemically modify these polymers. Described here are new poly(ethylene oxide) (PEO)–poly(β-6-heptenolactone) (PHEL) block copolymers having pendant alkenes at each repeat unit on the PHEL block. First, the self-assembly of these block copolymers in aqueous solution was studied and it was found that they formed solid nanoparticles and vesicles depending on the relative block lengths. Next the alkene moieties of the …
Synthesis, Self-Assembly, And Immunological Activity Of Α-Galactose-Functionalized Dendron–Lipid Amphiphiles, John Trant, Namrata Jain, D. M. Mazzuca, J Trevor Mcintosh, Bo Fan, S M Mansour Haeryfar, Sebastien Lecommandoux, Elizabeth Gillies
Synthesis, Self-Assembly, And Immunological Activity Of Α-Galactose-Functionalized Dendron–Lipid Amphiphiles, John Trant, Namrata Jain, D. M. Mazzuca, J Trevor Mcintosh, Bo Fan, S M Mansour Haeryfar, Sebastien Lecommandoux, Elizabeth Gillies
Chemistry Publications
Nanoassemblies presenting multivalent displays of biologically active carbohydrates are of significant interest for a wide array of biomedical applications ranging from drug delivery to immunotherapy. In this study, glycodendron–lipid hybrids were developed as a new and tunable class of dendritic amphiphiles. A modular synthesis was used to prepare dendron–lipid hybrids comprising distearylglycerol and 0 through 4th generation polyester dendrons with peripheral protected amines. Following deprotection of the amines, an isothiocyanate derivative of C-linked α-galactose (α-Gal) was conjugated to the dendron peripheries, affording amphiphiles with 1 to 16 α-Gal moieties. Self-assembly in …
Photocontrolled Degradation Of Stimuli-Responsive Poly(Ethyl Glyoxylate): Differentiating Features And Traceless Ambient Depolymerization, Bo Fan, John Trant, Rebecca Yardley, Andrew Pickering, Francois Lagugne-Labarthet, Elizabeth Gillies
Photocontrolled Degradation Of Stimuli-Responsive Poly(Ethyl Glyoxylate): Differentiating Features And Traceless Ambient Depolymerization, Bo Fan, John Trant, Rebecca Yardley, Andrew Pickering, Francois Lagugne-Labarthet, Elizabeth Gillies
Chemistry Publications
The depolymerization of coatings prepared from a 6-nitroveratryl carbonate end-capped poly(ethyl glyoxylate) (PEtG) self-immolative polymer was studied. This polymer undergoes end-to-end depolymerization following cleavage of the end-cap by UV light. Several important fundamental diff erences between this class of polymers and conventional degradable polymers were revealed. For example, polymer backbone cleavage and depolymerization exhibited different dependencies on pH, emphasizing the decoupling of these processes. Probing of the coating erosion mechanism illustrated an interesting combination of features from surface erosion and bulk degradation mechanisms that arise from the end-to-end depolymerization mechanism and further differentiate these polymers from convention degradable polymers. It …
Selective Oxygen Atom Insertion Into An Aryl-Palladium Bond, Ava Behnia, Paul D. Boyle, Johanna M. Blacquiere, Richard J. Puddephatt
Selective Oxygen Atom Insertion Into An Aryl-Palladium Bond, Ava Behnia, Paul D. Boyle, Johanna M. Blacquiere, Richard J. Puddephatt
Chemistry Publications
The chemistry of a palladium(II) complex containing both an alkyl- and an aryl-palladium bond is reported. The reaction of [Pd(CH2CMe2C6H4)(MesN=CHCH=NMes)] with bromine or iodine leads to reductive elimination of 1,1-dimethylcyclobutabenzene with formation of [PdX2(MesN=CHCH=NMes)] (X = Br, I). However, the reaction with hydrogen peroxide gives [Pd(CH2CMe2C6H4O)(MesN=CHCH=NMes)] by overall oxygen atom insertion into the aryl-palladium rather than the alkyl-palladium bond. This complex [Pd(CH2CMe2C6H4O)(MesN=CHCH=NMes)] reacts with bromine, iodine, or hydrogen peroxide to give 3,3-dimethyl-2,3-dihydrobenzofuran and the corresponding complex [PdX2(MesN=CHCH=NMes)]. The mechanisms of reaction and basis for selectivity are discussed. The results support the view that oxygen atom insertion is a mechanistically viable …
Synthesis, Characterization, And Pre-Ceramic Properties Of Π-Conjugated Polymers Based On Ni(Ii) Complexes Of Goedken’S Macrocycle, Joseph A. Paquette, Joe Gilroy
Synthesis, Characterization, And Pre-Ceramic Properties Of Π-Conjugated Polymers Based On Ni(Ii) Complexes Of Goedken’S Macrocycle, Joseph A. Paquette, Joe Gilroy
Chemistry Publications
Nickel(II) complexes of Goedken’s macrocycle bearing alkyne substituents were copolymerized with 2,7-dibromo-9,9-dihexylfluorene, 2,5-dibromo-3-hexylthiophene, and 1,4-dibromo-2,5-bis(hexyloxy)benzene via microwave-induced Sonogashira cross-coupling reactions to produce copolymers 6F, 6T, and 6B. The spectroscopic and electrochemical properties of the copolymers were examined and compared to model compounds. Specifically, each polymer exhibited a nickel-based absorption centered at ca. 589 nm and two π → π* transitions between 272 and 387 nm. While the copolymers did not exhibit extended π conjugation, the nature of the organic spacer did affect the high energy transitions. Furthermore, each copolymer underwent two ligand-based one-electron oxidations at potentials …
Aggregation-Induced Emission Enhancement In Boron Difluoride Complexes Of 3-Cyanoformazanates, Ryan R. Maar, Joe Gilroy
Aggregation-Induced Emission Enhancement In Boron Difluoride Complexes Of 3-Cyanoformazanates, Ryan R. Maar, Joe Gilroy
Chemistry Publications
Boron difluoride (BF2) complexes of 3-cyanoformazanates exhibit aggregation-induced emission enhancement in THF-water mixtures due to their severely twisted N-aryl substituents which restrict intramolecular motion and π stacking upon aggregation.
Synthesis, Properties, And Antibacterial Activity Of Polyphosphonium Semi-Interpenetrating Networks, Tyler John Cuthbert, Tristan Harrison, Paul J. Ragogna, Elizabeth Gillies
Synthesis, Properties, And Antibacterial Activity Of Polyphosphonium Semi-Interpenetrating Networks, Tyler John Cuthbert, Tristan Harrison, Paul J. Ragogna, Elizabeth Gillies
Chemistry Publications
The development of new approaches to antibacterial surfaces is of growing interest to combat the spread of harmful bacterial infections. Relative to polyammoniums, polyphosphoniums can exhibit enhanced chemical and thermal stability, but have not yet been widely explored for the preparation of antibacterial surfaces. In this work, polyphosphoniums of varying chain lengths were synthesized by reversible addition-fragmentation chain-transfer polymerization of 4-vinylbenzyl derivatives of triethyl, tributyl, and trioctylphosphonium. These polyphosphoniums were then incorporated into semi-interpenetrating networks (SIPNs) based on tetra(ethylene glycol) diacrylate (TEGDA) via a UV light-initiated curing process. Measurements of cure percentage, gel content, water contact angle, and surface charge …
Boron Difluoride Formazanate Copolymers With 9,9-Di-N-Hexylfluorene Prepared By Copper-Catalyzed Alkyne-Azide Cycloaddition Chemistry, Stephanie M. Barbon, Joe Gilroy
Boron Difluoride Formazanate Copolymers With 9,9-Di-N-Hexylfluorene Prepared By Copper-Catalyzed Alkyne-Azide Cycloaddition Chemistry, Stephanie M. Barbon, Joe Gilroy
Chemistry Publications
The synthesis and characterization of copolymers based on boron difluoride formazanate (BF2L) and 9,9-di-n-hexylfluorene (hex2Fl) units are described. A series of model compounds [(BF2L)-(hex2Fl), (hex2Fl)-(BF2L)-(hex2Fl), and (BF2L)-(hex2Fl)-(BF2L)] were also studied in order to fully understand the spectroscopic properties of the title copolymer [(BF2L)-(hex2Fl)]n. The model compounds and copolymers, which were synthesized by copper catalyzed alkyne-azide cycloaddition chemistry, exhibited high molar absorptivities (25,700-54,900 …
Poly(Ester Amide)S With Pendant Azobenzenes: Multi-Responsive Self-Immolative Moieties For Modulating Polymer Assemblies, Andrew D. Wong, Alex Prinzen, Elizabeth Gillies
Poly(Ester Amide)S With Pendant Azobenzenes: Multi-Responsive Self-Immolative Moieties For Modulating Polymer Assemblies, Andrew D. Wong, Alex Prinzen, Elizabeth Gillies
Chemistry Publications
Azobenzenes are well-known for their trans–cis photoisomerization, but it was recently demonstrated that azobenzene derivatives could also undergo reduction to trigger a 1,6-elimination and initiate de- polymerization of a self-immolative polymer. Herein we explore the optimization of azobenzenes as reduction-sensitive moieties, and their incorporation into functional materials. A library of azobenzenes with electron-withdrawing groups was synthesized, and their rates of reduction by hydrazine were deter- mined. Unexpectedly, a 2-Cl substituent increased the rate of reduction more than other electronegative or sterically-demanding substituents. Next, a new diester monomer containing the 2-Cl-azobenzene was synthesized and incorporated into a poly(ester amide) (PEA) backbone, …
Synthesis, Characterization, And Thin-Film Properties Of 6-Oxoverdazyl Polymers Prepared By Ring-Opening Metathesis Polymerization, Joseph A. Paquette, Sabastine Ezugwu, Vishal Yadav, Giovanni Fanchini, Joe Gilroy
Synthesis, Characterization, And Thin-Film Properties Of 6-Oxoverdazyl Polymers Prepared By Ring-Opening Metathesis Polymerization, Joseph A. Paquette, Sabastine Ezugwu, Vishal Yadav, Giovanni Fanchini, Joe Gilroy
Chemistry Publications
Redox-active 6-oxoverdazyl polymers were synthesized via ring-opening metathesis polymerization (ROMP) and their solution, bulk, and thin-film properties investigated. Detailed studies of the ROMP method employed confirmed that stable radical polymers with controlled molecular weights and narrow molecular weight distributions (Ð < 1.2) were produced. Thermal gravimetric analysis of a representative example of the title polymers demonstrated stability up to 190 °C, while differential scanning calorimetry studies revealed a glass transition temperature of 152 °C. Comparison of the spectra of 6-oxoverdazyl monomer 12 and polymer 13, including FT-IR, UV-vis absorption, and electron paramagnetic resonance spectroscopy, was used to confirm the tolerance of the ROMP mechanism for the 6-oxoverdazyl radical both qualitatively and quantitatively. Cyclic voltammetry studies demonstrated the ambipolar redox properties of polymer 13 (E1/2,ox = 0.25 and E1/2,red = −1.35 V relative to ferrocene/ferrocenium), which were …
Catalytic Cyclization And Competitive Deactivation With Ru(PR2nR′2) Complexes, J. M. Stubbs, J. P.J. Bow, R. J. Hazlehurst, J. M. Blacquiere
Catalytic Cyclization And Competitive Deactivation With Ru(PR2nR′2) Complexes, J. M. Stubbs, J. P.J. Bow, R. J. Hazlehurst, J. M. Blacquiere
Chemistry Publications
The first successful use of the PR2NR′2 (1,5-R′-3,7-R-1,5-diaza-3,7-diphosphacyclooctane) ligand family toward an organic synthesis is described. The precatalysts [Ru(Cp)(PR2NBn2)(MeCN)]PF6 are active toward cyclization of 2-ethynylbenzyl alcohol at low catalyst loading and mild temperatures. Catalyst performance however is limited by both low conscription and by competitive deactivation.
Pincer-Plus-One Ligands In Self-Assembly With Palladium(Ii): A Molecular Square And A Molecular Tetrahedron, Ava Behnia, Paul D. Boyle, Mahmood A. Fard, Johanna M. Blacquiere, Richard J. Puddephatt
Pincer-Plus-One Ligands In Self-Assembly With Palladium(Ii): A Molecular Square And A Molecular Tetrahedron, Ava Behnia, Paul D. Boyle, Mahmood A. Fard, Johanna M. Blacquiere, Richard J. Puddephatt
Chemistry Publications
The combination of a palladium(ii) precursor with a diimine-phenol ligand and an oxidant (H2O2 or O2) under different conditions has, serendipitously, given both a molecular square and a molecular tetrahedron by self-assembly of building blocks comprising palladium(ii) centres coordinated to the oxidised forms of the ligand.
Exact Expressions For The Kohn–Sham Exchange-Correlation Potential In Terms Of Wave-Function-Based Quantities, Rogelio Cuevas-Saavedra, Viktor N. Staroverov
Exact Expressions For The Kohn–Sham Exchange-Correlation Potential In Terms Of Wave-Function-Based Quantities, Rogelio Cuevas-Saavedra, Viktor N. Staroverov
Chemistry Publications
Several workers have deduced various exact expressions for the Kohn–Sham exchange-correlation potential in terms of quantities computable from the interacting and noninteracting wave functions of the system. We show that all these expressions can be obtained by one general method in which the interacting N-electron wave function is expanded in products of one- and (N − 1)-electron functions. Different expressions correspond to different choices of the latter functions. Our analysis unifies and clarifies the previously proposed exact treatments of the exchange-correlation potential, and suggests new ways of expressing this quantity.
Microbial-Physical Synthesis Of Fe And Fe3o4 Magnetic Nanoparticles Using Aspergillus Niger Yesm1 And Supercritical Condition Of Ethanol, Mai Abdeen, Soraya Sabry, Hanan Ghozlan, Ahmed A. El-Gendy, Everett E. Carpenter
Microbial-Physical Synthesis Of Fe And Fe3o4 Magnetic Nanoparticles Using Aspergillus Niger Yesm1 And Supercritical Condition Of Ethanol, Mai Abdeen, Soraya Sabry, Hanan Ghozlan, Ahmed A. El-Gendy, Everett E. Carpenter
Chemistry Publications
Magnetic Fe and Fe3O4 (magnetite) nanoparticles are successfully synthesized using Aspergillus niger YESM 1 and supercritical condition of liquids. Aspergillus niger is used for decomposition of FeSO4 and FeCl3 to FeS and Fe2O3, respectively. The produced particles are exposed to supercritical condition of ethanol for 1 hour at 300∘ C and pressure of 850 psi. The phase structure and the morphology measurements yield pure iron and major Fe3O4 spherical nanoparticles with average size of 18 and 50 nm, respectively. The crystal size amounts to 9 nm for Fe and 8 nm for Fe3O4. The magnetic properties are measured to exhibit …
Controlled Positioning Of Analytes And Cells On A Plasmonic Platform For Glycan Sensing Using Surface Enhanced Raman Spectroscopy, Mohammadali Tabatabaei, Gregory Q Wallace, Fabiana A Caetano, Elizabeth R Gillies, Stephen S G Ferguson, François Lagugné-Labarthet
Controlled Positioning Of Analytes And Cells On A Plasmonic Platform For Glycan Sensing Using Surface Enhanced Raman Spectroscopy, Mohammadali Tabatabaei, Gregory Q Wallace, Fabiana A Caetano, Elizabeth R Gillies, Stephen S G Ferguson, François Lagugné-Labarthet
Chemistry Publications
The rise of molecular plasmonics and its application to ultrasensitive spectroscopic measurements has been enabled by the rational design and fabrication of a variety of metallic nanostructures. Advanced nano and microfabrication methods are key to the development of such structures, allowing one to tailor optical fields at the sub-wavelength scale, thereby optimizing excitation conditions for ultrasensitive detection. In this work, the control of both analyte and cell positioning on a plasmonic platform is enabled using nanofabrication methods involving patterning of fluorocarbon (FC) polymer (C