黑料吃瓜不打烊

Research

1- Indirect electrode surface modifications via oxidative electropolymerization

2- Electrochemical/Biological polymer sensors

3- Radical functionalized oligo/polythiophenes

4- Electron transfer reactions

Our group is focused on the detection of biomolecules using chiral conducting surfaces (chiral electrodes). Our methodology ?displays several advantages such as i) easy to prepare and control the thickness, ii) carrying several chemical functionalities that allows an easier functionalization of the conducting surfaces as well as the introduction of new molecules with different electronic/optical properties iii) stability and regeneration of the conducting surfaces, and iv) facilitating immobilization and sensing of the desired molecules. ?In order to prepare chiral electrode, several mono and terthiophenes bearing amino acids such as (_D/L)-alanine, _(D/L)-leucine and (_D/L)-proline have been prepared.

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Chiral electrode have been prepared by deposition of chiral films on platinum or carbon electrodes by electrochemical oxidation? via repeated cyclic voltammetry scans beyond the oxidation peak potential ?of the chiral oligomers. The prepared chiral electrodes were characterized by cyclic voltammetry, and infrared. Moreover, the deposited films exhibit excellent chemical and electrochemical stability, which is a key point for discrimination of biomolecules.?In order to test the recognition ability of these electrodes, the capacitive current of the chiral electrode has been measured in the absence and presence of a free amino acid such as L-leucine methyl ester (LeuOMe). We found that the capacitive current of the chiral electrode decreases by 30% after addition of 1 or 5 mM of LeuOMe. The change observed in the capacitive current is attributed to the formation of hydrogen bonds between the chiral surfaces and the free amino acids in solution. Such hydrogen bond formation between the chiral electrode and CF₃COOH was confirmed by ATR-FTIR. (see insight front cover paper New J. Chem. 2014, 38, 3379-3385.)?

We are also interested in the synthesis and characterization of materials with multi-properties combining properties of conducting materials (polythiophenes) and stable radicals (nitroxides and verdazyl radicals), which will have application in energy storage. The presence of such radicals may affect the conducting and optical properties of these electrodes. For the first time, verdazyl radical? has been prepared? by electrochemical oxidation of the precursor (see New J. Chem. 2015, 39, 7738-7741. Letter)

Awards

??Undergraduate scholarship

Graduate scholarship

Teaching

Undergraduate?courses:

CHMI-2426E/F - Organic Chemistry? I.?This course presents an introduction to organic chemistry. Topics include structure and bonding, nomenclature, stereochemistry, and an introduction to the chemistry of a few classes of organic compounds. PREREQ: CHMI 1006/7. (lec 3, lab 3, tut 1) cr 3.

CHMI-2427E/F - Organic Chemistry?II.?This course includes a detailed investigation of the reactions of hydrocarbons, and monofunctional organic compounds. Factors which affect the reactions are also discussed.??PREREQ: CHMI-2427. (lec 3, lab 3, tut 1) cr 3.

CHMI-3416E/F-Intermediate Organic Chemistry.?This course involves the application of spectroscopic methods (N.M.R., U.V., I.R. and mass spectrometry) to the determination of structures of organic compounds, and examines the chemistry of aromatic compounds including phenols, arylhalides and polynuclear hydrocarbons. PREREQ: CHMI 2427. (lec 3, lab 3) cr 3.

CHMI-1202E/F-Organic Chemistry and Biochemistry for the Health Sciences.?An introduction to organic chemistry with emphasis on the structure, physical properties, nomenclature and chemical reactions of alkanes, alkenes, alkynes, cyclic aliphatic and aromatic compounds, alcohols, ethers, aldehydes, ketones, carboxylic acids, amines as well as select sulfur and phosphorus-containing compounds. Examines the structure and function of common carbohydrates such as glucose and its polymers, amino acids, peptides and proteins, an introduction to enzymes, DNA and RNA, the problem of DNA replication and protein synthesis. Students may not retain credit for more than one of CHMI 1030, 1032 & 1202. PREREQ: OAC or U level credit in chemistry or CHMI 1041. (lec 3, lab/tut 2) cr 3.

CHMI-3116E/F-Instrumental Techniques in Chemical, Biochemical and Environmental Sciences. The course presents the principles and components of modern instruments currently used in chemical, biological, biochemical and environmental sciences, including forensic and pharmaceutical sciences to measure and characterize elements, ions, small and large molecules and compounds. It covers the main divisions of instrumental analysis based on: 1) separation techniques such as gas, liquid and supercritical chromatography, electrophoresis, gel permeation/filtration; 2)spectroscopy, spectrometry and optical phenomena such as ultra-violet, visible, infra-red, luminescence and fluorescence techniques, atomic spectrometry, surface plasmon resonance, X-ray techniques, radioactivity measurements, mass spectrometry; and 3) electrochemical methods based on potentiometry, voltammetry and biosensors. The interfacing of instruments (hyphenated techniques) is also covered and numerous applications are presented. PREREQ: CHMI 2117. (lec 3, lab 3) cr 3.

Graduate courses:

CHMI-5137E-Advanced electrochemistry.?This course will focus on the physical properties of charged electrode/solution interfaces and the chemical processes that occur as a result of changes in electrical energy at those interfaces. Topics include: a review of electrode processes and thermodynamics of electrochemical cells; electrochemical instrumentation; electric double-layer structure and adsorption; electrode reaction kinetics and potential sweep methods. Advanced topics include electrode reactions coupled with homogeneous chemical reactions as well as spectro-electrochemistry. (3 credits)

CHMI-5118E-01/Mass spectroscpy.?A discussion of the principles of mass spectroscopy with reference to various ionizations and analyzer techniques, as well as interfacing with other instruments. A major part of the course will be considering the application of mass spectroscopy to qualitative and quantitative chemical analysis. One lecture per week, one term.

CHMI-5128-01E/Perf.-Liquid Chromatography.?The principles features of high performance liquid chromatography (HPLC) will be discussed. Its high sensitivity will be related to detector technology, while its high analytical selectivity will be related to variations in the mobile and stationary phase. The applications of reverse phase and chiral phase HPLC will be discussed. One lecture per week, one term.

CHMI-5138-01E/Advanced NMR Spectroscopy.?A brief review of the basic principles of Nuclear Magnetic Resonance (NMR) spectroscopy will be followed by a discussion of spin relaxation and the Nuclear Overhausser Effect. The discussion will be extended to multinuclear experiments including 15N and 31P Nuclei. A major part of the course will consider the modification of pulse sequences in order to observe special 1D spectra and 2 D correlation spectra. Developments in solid-state NMR (MAS technology) will also be discussed. One lecture per week, one term.

E= English; F=French

Publications

Selected publications:

M. Chahma. "Doped Polythiophene Chiral Electrodes as Electrochemical Biosensors".

? ? ? ? ? ? ? ?Electrochem. 2021, 2, 677-688.

M.Chahma, R. Riopel? and G. Arteca. "Synthesis, characterization and modeling of stable radical functionalized monothiophenes".

? ? ? ? ? ? ? ?J. Sulfur Chem. 2021, 42, 464-475.

M. Chahma and C. Carruthers. "Electrochemical detection of oligonucleotides using polypyrroles".

? ? ? ? ? ? ? ?Sensors and Actuators Reports, 2021, 3, 100039.?Review

M. Chahma and S. Almubayedh “Synthesis and characterization of terthiophene bearing stable radicals".

? ? ? ? ? ? ? ?Can. J. Chem. 2021, 99, 24-30.

J. G. Ibanez, M. E. Rincon, S. Gutierrez-Granados, M. Chahma, O. A. Jaramillo-Quintero, and B. A. Frontana-Uribe. “Conducting Polymers in the Fields of Energy, Environmental Remediation, and Chemical–Chiral Sensors”.

? ? ? ? ? ? ? ?Chem. Rev.??2018,?118, 4731-4816.?Review

S. Almubayedh and M. Chahma, “Electro-synthesis and characterization of verdazyl radical functionalized oligo/polythiophenes”

? ? ? ? ? ? ? ?New J. Chem. 2015,?39, 7738-7741.?Letter

K. M. Koczkur, E. M. Hamed,? M. Chahma, D. F. Thomas and A. Houmam, “Electron Transfer Initiated Formation of Covalently Bound Organic Layers on Silicon Surfaces”

? ? ? ? ? ? ? ?J. Phys. Chem. C,?2014.?118, 20908–20915.

Chahma, M; McTiernan, M.D.; Abbas, S. A.; “Characterization of phenomena occurring at the interface of chiral conducting surfaces”.

? ? ? ? ? ? ? ?New. J. Chem. 2014, 38,?3379-3385.??Inside front cover for August issue

McTiernan, M.D.; Abbas, S. A.; Chahma, M. “Organic surface modification using stable conducting materials”.

? ? ? ? ? ? ? ?New. J. Chem. 2012,?36, 2106–2111.

McTiernan, M. D.; Chahma, M. “Chiral conducting surfaces based on the electropolymerization of 3,4-ethylenedioxythiophene”.

? ? ? ? ? ? ? ?Synth. Met. 2011,?161, 1532-1536.

McTiernan, M. D.; Omri, K.; Chahma, M. “Chiral conducting surfaces via electrochemical oxidation of L-leucine-oligothiophenes”.

? ? ? ? ? ? ? ?J. Org. Chem.?2010,?75, 6096-6103.

Chahma, M.; Li, X.; Phillips, L. P.; Schwartz, P.; Brammer, L. E.; Wang, T.;? Tanko, J. M. “Activation/driving force relationships for cyclopropylcarbinyl homoallyl-type rearrangements of radical anions”.?

? ? ? ? ? ? ? ?J. Phys. Chem. A.?2005,?109, 3372-3382.

Chahma, M.; Combellas, C.; Thiébault, A. “Delocalized nitrogen carbanions in S_RN1 reactions”.

? ? ? ? ? ? ? ?J. Org. Chem. 1995,?60,?8015-8022.