Microstructures in thin polymeric films. Photochemically produced molecular voids

Calculation of Electron Transfer Rate Constants from Emission Spectra in Re(I) Chromophore−Quencher Complexes

“…In the study of electron transfer, energy transfer, and nonradiative decay, an important development has been the recognition of the close relationship between spectroscopy and reaction dynamics. − Theoretical expressions have been derived which relate rate constants to molecular quantities such as reorganizational energies, driving forces, and the coupling matrix elements that mix states, all of which can be measured in favorable cases. The application of these ideas has led to the use of emission, absorption, and resonance Raman spectra to evaluate reaction barriers and rate constants for electron and energy transfer in the normal and inverted regions, and for nonradiative decay. − …”

“…Following Re I → 4,4‘-R 2 bpy excitation and 4,4‘-R 2 bpy → LA electron transfer to give fac- [(4,4‘-R 2 bpy)Re II (CO) 3 (LA •- )] n + , LA •- → Re II back electron transfer occurs and can be time-resolved by transient absorption measurements because the one-electron-reduced quinone and pyridinium ligands have characteristic absorption features in the near-UV and visible. Most importantly, all of these complexes emit, and analysis of the emission gives the parameters required to calculate both the electron-transfer barrier and electron-transfer coupling matrix elements. − A preliminary account of this work has appeared …”

Photolithographically-Patterned Electroactive Films and Electrochemically Modulated Diffraction Gratings

“…More recently, Meyer and co-workers devised a general strategy for producing arbitrary micropatterns of electropolymerized films on conducting substrates. ,− Meyer's strategy relies on the photochemical lability of pyridyl ligands in complexes of the type [(bpy)Ru II (py) 2 ] 2+ , where bpy is 2,2‘-bipyridine or a related bidentate ligand and py is a substituted pyridine ligand. Thus, in the presence of a suitable nucleophile such as halide (X - ) or dimethylthiocarbamate (dmdtc - ), [(bpy)Ru II (py) 2 ] 2+ and related complexes undergo photosubstitution of the pyridyl ligands to afford the corresponding mono- and di-substituted complexes [(bpy)Ru II (py)(X)] + and [(bpy)Ru II (X) 2 ] .…”

“…Photolysis of poly-[(bpy) 2 Ru(vpy) 2 ] 2+ films through a contact photolithographic mask followed by development of the latent image with a suitable solvent allows formation of arbitrary micropatterns with spatial resolution on the order of 30 μm. In a series of publications Meyer and co-workers extended this methodology to a variety of metal complexes that are structurally related to [(bpy) 2 Ru(vpy) 2 ] 2+ . ,− Moreover, they demonstrate the use of poly-[(bpy) 2 Ru(vpy) 2 ] 2+ and related photochemically reactive redox polymers as positive tone photoresists to control the patterning of other electropolymerizable monomers such as Ru(vbpy) 3 2+ and Os(vbpy) 3 2+ (vbpy = 4-vinyl-4‘-methyl-2,2‘-bipyridine).

1

…”

“…Most work in the area of modified electrodes has focused on approaches to producing films that are spatially homogeneous in the plane defined by the electrode surface. − However, within the past decade a number of groups have devised methods for modifying electrodes with electroactive films that are microscopically patterned within the plane defined by a surface. ,− These methods include laser writing, − ,, e-beam writing, , photolithography, ,− ,− ,, microcontact printing, ink-jet printing, , and holography . Although these efforts have been motivated primarily by interest in basic science, it is possible to envision a number of technologically important uses for surfaces that are modified with microscopically patterned redox- or electronically-conducting polymer films such as fabrication of microelectronic or -photonic devices 31,41 or microsensor arrays …”