A comprehensive study of a series of four monodisperse, metal-organic pi-conjugated oligomers of varying length is reported. The oligomers are based on the aryleneethynylene architecture, and they contain a 2,2'-bipyridine-5,5'-diyl (bpy) metal binding unit. The photophysical properties of the free oligomers and their complexes with the (L)Re(I)(CO)(3)X chromophore (where L = the bpy-oligomer and X = Cl or NCCH(3)) were explored by a variety of methods including electrochemistry, UV-visible absorption, variable temperature photoluminescence (PL), transient absorption (TA), and time-resolved electron paramagnetic spectroscopy (TREPR). The absorption of the free oligomers and the metal complexes is dominated by the pi,pi* transitions of the pi-conjugated oligomers. The free oligomers feature a strong blue fluorescence that is quenched entirely in the (L)Re(I)(CO)(3)X complexes. The metal-oligomers feature a weak, relatively long-lived red photoluminescence that is assigned to emission from both the (3)pi,pi* manifold of the pi-conjugated system and the dpi Re --> pi* bpy-oligomer metal-to-ligand charge transfer ((3)MLCT) state. On the basis of a detailed analysis of the PL, TA, and TREPR results an excited-state model is developed which indicates that the oligomer-based (3)pi,pi* state and the (3)MLCT states are in close energetic proximity. Consequently the photophysical properties reflect a composite of the properties of the two excited-state manifolds.

This manuscript presents an overview of work directed toward the creation of arbitrary micron-scale patterns of electroactive polymer films by the application of photolithography. A brief overview of work by other groups in the field is followed by a detailed description of work from our own labs which resulted in the development of methods to pattern a variety of different electroactive materials, including Ru-and Os-polypyridine complexes, viologen-based polymers, and a low-potential polythiophene. The discussion provides detail on the photolithographic methodology. In addition, the spatially-patterned films are characterized by using optical and scanning electron microscopy. The voltammetric and spectroelectrochemical properties of several of the lithographically-patterned films are also presented. Finally, photolithography is applied to fabricate electrochromic optical diffraction gratings. The diffraction efficiency of these electroactive gratings can be modulated by an electrochemical stimulus. The properties and mechanism for operation of the electrochromic gratings are described.