Department of Chemistry

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https://hdl.handle.net/10315/2685

Collection consists of research, scholarship and publications produced by graduate students and faculty members of the Department of Chemistry.

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Open Access
1,8-Naphthalene Linked Cofacial Binuclear Phthalocyanines
(Wiley-Blackwell, 1987) Lever, A.B.P.; Janda, Pavel; Kobayashi, Nagao; Nevin, Andrew W.; Lam, Herman; Leznoff, Clifford C.
Open Access
1999 Alfred Bader Lecture. From Early Developments in Multi-Step Organic Synthesis on Solid Phase to Multi-Nuclear Phthalocyanines.
(Canadian Journal of Chemistry, NRC Research Press, 2000) Leznoff, Clifford C.
Early developments in solid phase organic synthesis are traced. Particular emphasis is placed on the use of cross-linked polystyrene in the first general method of monoblocking symmetrical difunctional compounds. The monoprotected polymer-bound symmetrical starting materials were then used in multi-step syntheses of a variety of compounds, particularly insect pheromones. Asymmetric synthesis on polymer supports was demonstrated. Diels-Alder and 1,3-dipolar additions on polymer supports proceeded readily as did macrocyclic formation of porphyrins and phthalocyanines. All of these reactions clearly showed that most organic chemical reactions could be performed on solid phases and laid the basis for the development of combinatorial chemistry. The first unsymmetrical phthalocyanine was prepared using the solid phase method and this led eventually to solution phase methods of preparing bi-, tri-, tetra-, and even a dendritic-like pentanuclear phthalocyanine.
Open Access
2,4-Di-O-methylgyrophoric Acid and 2,4,5-Tri-O-methylhiascic Acid. New Tridepsides from Parmelia damaziana
(CSIRO Publishing, 1981) Leznoff, Clifford C.; Jayanthi, Vilas K.; Elix, John A.
Open Access
Ab-initio investigation of Br-3d core-excited electronic structures of HBr and HBr+
(AIP Publishing, 2019-01-30) Kobayashi, Yuki; Zeng, Tao; Neumark, Daniel M.; Leone, Stephen
Ultrafast X-ray absorption spectroscopy is a powerful tool for real-time probing of chemical dynamics. Interpretation of the time-resolved absorption spectra requires knowledge of core-excited potentials, which necessitates assistance from high-level electronic-structure computations. In this study, we investigate Br-3d core-excited electronic structures of hydrogen bromide (HBr) using the spin-orbit general multiconfigurational quasidegenerate perturbation theory (SO-GMC-QDPT). Core-to-valence excitation energies and transition dipole moments are computed as functions of the internuclear distance for five electronic states of HBr (1Σ0+ , 3Π1, 1Π1, 3Π0+ , 3Π1) and two electronic states of HBr+ (2Π3/2, 2Σ1/2). The results illustrate the capabilities of the Br-3d edge probing to capture transitions of electronic-state symmetry as well as nonadiabatic dissociation processes evolving across avoided crossings. Furthermore, core-to-valence absorption spectra are simulated from the neutral and ionic ground states by numerically solving the time-dependent Schrodinger equation, which exhibit an excellent agreement with an experimental spectrum. The calculated comprehensive and quantitative picture of the core-excited potentials allows for transparent analyses of the core-to-valence absorption signals, filling the gap in the theoretical understanding of the Br-3d absorption spectra.
Open Access
"Adjacent" Substituted Phthalocyanines
(Georg Thieme Verlag, 1997) Leznoff, C.C.; Hu, M.; Nolan, K.J.M.
Open Access
The Alkaline Decomposition of o-Phthalaldehyde Di-p-toluene Sulfonylhydrazone
(NRC Research Press, 1968) Leznoff, Clifford C.
Open Access
Analysis of the role played by ligand-induced folding of the cocaine-binding aptamer in the photochrome aptamer switch assay
(Elsevier, 2020-04-11) Shoara, Aron A.; Churcher, Zachary R; Steele, Terry W.J.; Johnson, Philip E
The Photochrome Aptamer Switch Assay (PHASA) relies on ligand binding by an aptamer to alter the local environment of a stilbene compound covalently attached to the 5’ end of the aptamer. We used the PHASA with both structure switching and non-structure switching versions of the cocaine-binding aptamer. We show that the largest change in fluorescence intensity and the lowest concentration limit of detection (CLooD) is obtained using the structure-switching cocaine-binding aptamer. Fluorescence anisotropy measurements were used to quantify the affinity of the conjugated aptamer to cocaine. We also used thermal melt analysis and Nuclear Magnetic Resonance (NMR) spectroscopy to show that the addition of the stilbene to the aptamer increases the melt temperature of the cocaine-bound structure-switching aptamer by (6.4 ± 0.3) °C compared to the unconjugated aptamer while the free form of the structure-switching aptamer-stilbene conjugate remains unfolded.
Open Access
Approaches Towards the Synthesis of a 2,9,16,23-Tetrasubstituted Phthalocyanine as a Pure Isomer
(NRC Research Press, 1988) Leznoff, Clifford C.; Lever, A.B.P.; Greenberg, Shafrira
Open Access
Aptamers 2017 at Oxford
(2018-02-12) Henri, Justin; McKeague, Maureen; Johnson, Philip E; Suess, Beatrix; Nakamura, Yoshikazu; Nilsen-Hamilton, Marit; Pastor, Fernando; Hahn, Ulrich; Bunka, David; Shigdar, Sarah
The 4th annual symposium of the International Society on Aptamers, Aptamers 2017, was held in Oxford on the 11th and 12th April and was well attended, with presenters from Europe (Spain, Germany, Austria, and UK), North and South America, Asia, and Australasia presenting on a diverse range of topics, from enhancing SELEX, to diagnostic applications such as lateral flow devices or medical imaging, to therapeutic applications such as drug delivery. The conference was split into six sections in total, covering chemical modifications, disease, analysis/diagnostics, tools/selection/design, riboswitches, and computation with over 50 oral and poster presentations. The conference started with a welcome from both the Symposium Chair, Professor Dr Ulrich Hahn (University of Hamburg, Germany) and the President of the International Society on Aptamers, Dr Sarah Shigdar (Deakin University, Australia).
Open Access
Aptamers 2018 – a conference update
(2018-06-29) Tanner, Julian A; Ismail, Said I; Shigdar, Sarah; DeRosa, Maria C; Hahn, Ulrich; Johnson, Philip E; Suess, Beatrix; McKeague, Maureen
The 5th annual symposium of the International Society on Aptamers, Aptamers 2018, was held in Oxford on the 11th and 12th April. We had a very diverse group of attendees and presenters from all over the world with representatives from both academia and industry. This year, the conference included a Lifetime Achievement Award presented to Emeritus Professor Dr Uli Hahn from the University of Hamburg and a very successful “Flash Talks” session.
Open Access
Aptamers 2019 – a conference update
(2019-07-14) Shigdar, Sarah; Johnson, Philip; Pietruschka, Georg; Legen, Tjaša; Mayer, Günter; McKeague, Maureen
The International Society on Aptamers held Aptamers 2019, the sixth successful annual symposium at Oxford in April. The meeting was chaired by Professor Dr Günter Mayer. The participants, representing over 25 countries, included some familiar faces as well as several new ones (~40% PIs/ postdocs, 25% students, and 35% from the industry)! A wide range of topics were covered in in 25+ oral presentations, 15+ flash-talks and 45+ posters. Below, we have briefly discussed some of the highlights of the symposium.
Open Access
Asymmetric Induction in the Cycloaddition of 1,3-Butadienes to Polymer-Bound Chiral Acrylates
(Elsevier, 1988) Leznoff, Clifford C.; McArthur, Colin R.; Corbridge, Michael D.
Open Access
Asymmetric Syntheses Towards (3Z,6R)-3-Methyl-6-isopropenyl-3,9-decadien-1-yl Acetate, a Component of the California Red Scale Pheromone
(NRC Research Press, 1985) Leznoff, Clifford C.; McArthur, Colin R.; Whittaker, Mark
Open Access
Asymmetric Synthesis of 2-Alkylcyclohexanones on Solid Phases
(Wiley-Blackwell, 1979) Leznoff, Clifford C.; McArthur, Colin R.; Worster, Paul M.
Open Access
The Asymmetric Synthesis of 4,4-Dimethyl-3-substitutedbutyrolactones
(Taylor & Francis, 1986) Whittaker, Mark; McArthur, Colin R.; Leznoff, Clifford C.
Open Access
Attraction of Various Tortricine Moths to Blends Containing Cis-11-tetradecenal
(Springer Verlag, 1978) Fyles, T.M.; Leznoff, C.C.; Werner, R.A.; Frech, D.; L.M., MacDonald; Grant, G.G.; Weatherston, J.
Open Access
BF3‑Catalyzed Intramolecular Fluorocarbamoylation of Alkynes via Halide Recycling
(American Chemical Society, 2023-05-12) McKnight, E. Ali; Arora, Ramon; Pradhan, Ekadashi; Fujisato, Yuriko H.; Ajayi, Ayonitemi, J.; Lautens, Mark; Zeng, Tao; Le, Christine M.
A BF3-catalyzed atom-economical fluorocarbamoylation reaction of alkyne-tethered carbamoyl fluorides is reported. The catalyst acts as both a fluoride source and Lewis acid activator, thereby enabling the formal insertion of alkynes into strong C–F bonds through a halide recycling mechanism. The developed method provides access to 3-(fluoromethylene) oxindoles and γ-lactams with excellent stereoselectivity, including fluorinated derivatives of known protein kinase inhibitors. Experimental and computational studies support a stepwise mechanism for the fluorocarbamoylation reaction involving a turnover-limiting cyclization step, followed by internal fluoride transfer from a BF3-coordinated carbamoyl adduct. For methylene oxindoles, a thermodynamically driven Z–E isomerization is facilitated by a transition state with aromatic character. In contrast, this aromatic stabilization is not relevant for γ-lactams, which results in a higher barrier for isomerization and the exclusive formation of the Z-isomer.
Open Access
Bifunctional Resins Applications to the Synthesis of Insect Sex Attractants
(NRC Research Press, 1978) Weatherston, John; Leznoff, Clifford C.; Fyles, Thomas M.
Open Access
Binuclear Phthalocyanines Covalently Linked Through Two and Four Atom Bridges
(NRC Research Press, 1985) Leznoff, Clifford C.; Lever, A.B.P.; Greenberg, Shafrira; Svirskaya, Polina I.; Marcuccio, Sebastian M.
Open Access
Binuclear Phthalocyanines with Aromatic Bridges
(NRC Research Press, 1989) Cerny, Ronald; Leznoff, Clifford C.; Lever, A.B.P.; Greenberg, Shafrira; Svirskaya, Polina I.; Marcuccio, Sebastian M.; Lam, Herman