Synthesis, photochemistry, and electrochemistry of a series of phthalocyanines with graded steric hindrance

The synthesis, photochemistry and electrochemistry of a series of phthalocyanines with graded steric hindrances are discussed. It appeared that although steric crowding of the triplet state of the silicon phthalocyanines was very effective at reducing the rate constants of exoergic electron exchange energy transfer (TT) reactions, but it was less effective at discriminating against electron transfer (ET) processes. It was apparent that steric crowding of the photogenerated excited state was more effective in discriminating against the energy transfer process even for the small energy-acepting entities such as O₂.