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- Modification of Monolayers and Their Applications

Chemically Modified Electrodes (CMEs). - Modification of Monolayers and Their Applications. State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences. Contents. History and Development of CMEs Classification of CMEs

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- Modification of Monolayers and Their Applications

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  1. Chemically Modified Electrodes (CMEs) - Modification of Monolayers and Their Applications State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences

  2. Contents • History and Development of CMEs • Classification of CMEs • Orientated Monolayer & Classification of Kaleidoscopic SAMs • Several Examples

  3. 1. Early of 1970’s, F.C. Anson (CalTech), theory of chemical adsorption and adlayer structure. 2. 1973, R.F. Lane (Hawaii) & A.T. Hubbard (Cincinnati), olefin derivatives at Pt surface. 3. 1975, L.L. Miller (Colorado State), asymmetric reagent for preparing chiral electrode, electrosynthesis of optical rotation substance, electrode-selective reaction. 4. R.W. Murray (North Carolina), Covalent modification, metal oxide (SnO2) + silicane - monolayer modification. 5.T. Kuwana (Ohio State), Cyanourea Acyl Chloride/Graphite Early Studies on CMEs

  4. Covalent Bonding Carbon Series Metal Oxide & Semiconductors Electrochemical Polymerization Chemical Polymerization Plasma Polymerization Radiation Polymerization Dipping Dropping Rotating Electrodeposition Classification of CMEs Chemically Modified Electrodes (CMEs) Multilayer Monolayer Composite & Others Adsorption Polymer Thin Film Vapor Deposition Underpotential Deposition (UPD) Monomer Polymer LB & SA Films Irreversible Adsorption Simply by Physical/ Chemical Adsorption By Chemical Synthesis

  5. Merit: Function & Structure - tunable & controllable Applications: Electrosynthesis & Electrocatalysis ChemiSensors & Biosensors Electroanalysis & Electrochemical Detection Electrolyzing, Electroplating & Fuel Cell The understanding of the interrelationship between the molecular structure of amphiphiles and their organization on different surfaces is a fundamental problem. The packing and orientation of such molecules affect the surface chemistry of the monolayer, and play an important role in the phenomena of boundary lubrication, corrosion inhibition, adhesion, and catalysis.

  6. Orientated Monolayer Origin of the oil-on-water and LB film, 1. Aristotle - spread oil droplets on a water surface and used the behavior of the film to foretell the future. 2. 1774, Benjamin Franklin, the first preparation of LB film, and show the thickness of the oil layer is a few nanometers. 3. 1891, Agnes Pockels, the first monolayers at the water-air interface. 4. 1899-1913, Rayleigh, Devaus, and Hardy, the nature of these layers, and the amphiphilic structure. 5. 1917, Langmuir, the first systematic study of monolayers of amphiphilic molecules at the water-air interface. 6. 1935, Blodgett, the first study on a deposition of multilayers of long chain carboxylic acid onto a solid substrate. Deposition of a monolayer from the water-air interface to a vertical plate.

  7. Self-Assembled Monolayers Classical SAM literatures, 1. Bigelow , W.C.; Pickett,D.L.; Zisman, W.A. J. Colloid Interface Sci.1946, 1, 513. 2. Zisman, W.A. Adv. Chem. Ser.1964, 43, 1. 3. Sagiv, J. J. Am. Chem. Soc.1980, 102, 92. Several typical examples of organic monolayers Organosilicon/Hydroxylated surfaces (SiO2/Si, Al2O3/Al, Glass, etc.) Alkanethiols/Au, Ag, Cu Dialkyl sulfides, dialkyl disulfides/Au Alcohols, amines, pyridines/Au, Pt Carboxylic acids/Al2O3, Ag (acid-base interaction --> salt) Self-assembled monolayers are molecular assemblies that are formed spontaneously by the immersion of an appropriate substrate into a solution of an active surfactant in an organic solvent.

  8. Surface group Alkyl, or derivatized- alkyl group Interchain van der waals and electrostatic interactions Surface-active headgroup Chemisorption Surface Self-Assembled Monolayers Electroactive Groups in SAMs Ferrocene Viologen Quinone Porphyrin Bioactive Molecules in SAMs Electroactive Biomolecules in SAMs Inorganic composites and particles in SAMs A schematic view of the forces in a self-assembled monolayer Polymers in SAMs

  9. Extended SAM Systems Small Organic Molecules -Classical SAMs Inorganic Ions/Atoms Metal Atoms UPD of Ag, Cu, Ni, Pb, etc. I-/I Neutral Charged negatively, or positively Conjugated Chain Non-conjugated Different Headgroups, eg. -SH, Pyridyl, etc. S2-/Sca.1- SCN- NSC- CN- (unconventional SAM systems) Tail group Bulk Chain Headgroup

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