Quinone-substituted monometalated porphyrin dimers: models for photoinduced charge separation at fixed orientation and energy

Among the most significant issues currently being debated in the area of photosynthesis are those that concern the role that interchromophore interactions play in the initial charge separation process. In recent years a number of model compounds have been prepared in an effort to understand natural photosynthetic systems. The models reported to date, however, have nearly all consisted of a simple monomeric porphyrin covalently linked to one or more redox active groups and as a result have provided little insight into how interchromophore interactions might influence multistep photoinduced electron transfer reactions. The authors have therefore prepared a new series of photosynthetic models: the selectively metalated, quinone-substituted gable and flat dimers. These dimers contain the key biomimetic components, metalloporphyrin (ZnP), free-base porphyin (H/sub 2/P), and quinone (Q), held in several well-defined configurations. They provide the first matched set of photosynthetic models suitable for studying interchromophore orientation and energetic effects.