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The photochemical and thermal reactivity of a number of acyl azide-substituted pyridine compounds, namely nicotinyl azide, isonicotinyl azide, picolinyl azide and dinicotinyl azide with investigated as saturated monolayers on a single-crystal Pt(111) surface in an ultrahigh vacuum chamber. Multilayers of the substrates exhibited a maximum rate of desorption at 270 K, above which, stable saturated monolayers formed as characterized by reflection-absorption infrared spectroscopy by observation of C=O and N3 bands at 1700 cm−1, and 2100 and 1300 cm−1 respectively. The monolayers were stable up to 400 K. Photolysis of the monolayer (or heating above 400 K) results in the formation of the respective isocyanate intermediate after loss of nitrogen as evidenced by the appearance of a new infrared band at 2260 cm−1 with concomitant loss of the azide bands. The resulting isocyanate saturated monolayer is stable in absence of nucleophiles, but can be quenched with appropriate nucleophiles. [ABSTRACT FROM AUTHOR]

Irradiation of saturated monolayers of 3- and 4-substituted pyridyl diazoacetates on single-crystal Pt surfaces leads to either the corresponding reactive carbene or stable ketene intermediate with the chemoselectivity determined by the position of the photoreactive substituent on the pyridyl ring, which ultimately directs the available interactions with neighboring substrates. L'irradiation de monocouches saturées de diazoacétates de pyridyles substitués dans les positions 3 et 4 sur des surfaces de monocristaux de platine conduit à la formation soit du carbène réactif correspondant ou de l'intermédiaire cétène stable dans lesquels la chimiosélectivité est déterminée par la position du substituant photoréactif sur le noyau pyridyle qui en fin de compte dirige les interactions disponibles avec les substrats avoisinants. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Chemistry is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Chemistry is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: An electroactive self-assembled monolayer (SAM) was fabricated by covalent attachment of a novel hydroquinone-terminated dodecanethiol onto the gold surface and its electrochemical behavior was investigated using cyclic voltammetry and electrochemical impedance spectroscopy. The capability of the designed SAM in immobilization of organic molecules onto the gold surface was studied utilizing the Michael-addition as a model reaction. The results obtained from cyclic voltammetry, electrochemical impedance and grazing incidence Fourier transform infrared (GI-FTIR) spectroscopy revealed that, upon applying an anodic potential to the Au-SAM electrode system in the presence of glutathione, the electrochemically generated p-quinone participated in a Michael-addition reaction with glutathione and the corresponding Michael adduct was formed at the solid–liquid interface. The kinetic parameters were then derived for this interfacial Michael-addition reaction. [Copyright &y& Elsevier]

The reductive desorption of a self-assembled monolayer (SAM) of a fluorescent thiol molecule (BodipyClOSH) from Au was characterized using electrochemistry and epi-fluorescence microscopy. Molecular luminescence is quenched near a metal surface, so fluorescence was only observed for molecules reductively desorbed and then separated from the electrode surface. Fluorescence imaging showed that reductive desorption was selective, with desorption occurring from different regions of the Au electrode depending on the extent of the negative potential excursion. When desorbed, the molecules were sufficiently mobile, diffusing away from the electrode surface, thereby preventing oxidative readsorption. At sufficiently negative desorption potentials, all of the thiol was desorbed from the electrode surface, resulting in fluorescence at the air/solution interface. The selective removal of the thiol monolayer from distinct regions was correlated to features on the electrode surface and was explained through potential-dependent interfacial energies. This in situ electrofluorescence microscopy technique may be useful in sensor development. [ABSTRACT FROM AUTHOR]