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The enantioselective quenching of (Ln dpa 3)3- luminescence by Co(III) complexes with four NH3 ligands and one nucleotide ligand was investigated. Circularly polarized luminescence measurements revealed that small concentrations of dissymmetric quencher molecules in a solution with a racemic excited-state population of luminophores can yield a significant enantiomeric excess in the Ln* population. The degree of enantioselectivity is higher than expected and there exists a significant variation in the relative sign of E(sub q) values.

The iron-sulfur reaction center of the green sulfur bacterium Chlorobium vibrioforme was investigated. Membrane preparations that were active in NADP+ photoreduction were used. Flash kinetic spectrophotometry and electron paramagnetic resonance spectroscopy were used to identify the iron-sulfur redox centers on the acceptor side of the reaction center that are functionally involved in physiological electron transfer and to determine their kinetic interactions.

An electron paramagnetic resosnance (EPR) study of the Fe-bearing reaction centers from Rb. sphaeroides R26 sheds light on the electron transfer mechanism in photosynthesis. The EPR signals for both protonated and deuteroated chlorophylls show an absorption/emission/absorption pattern that can be explained in terms of an extended electron spin polarization model. The pattern suggests sequential formation and polarization of radical pairs. Its progression depends on the lifetimes of the chlorophyll/pheophytin pair.