MOLECULAR-STRUCTURES AND OPTICAL-PROPERTIES OF AGGREGATED FORMS OF CHLOROPHYLLS ANALYZED BY MEANS OF MAGNETIC CIRCULAR-DICHROISM

Magnetic circular dichroism (MCD) spectra were measured on chlorophyll s in different aggregation states formed in organic solvents and in pi gment-protein complexes. An index which reflects the magnetic dipole c ontribution of a specific transition is introduced, that is, a ratio o f MCD intensity of Faraday B-term (B) to that of dipole strength (D) ( B/D). The absolute value of the index is higher in monomeric chlorophy ll a and that in monomeric bacteriochlorophyll a. This index changed d epending on the aggregation state of bacteriochlorophyll; in the case of the dimer of bacteriochlorophyll a and bacteriochlorophyll d, the v alue was nearly the half of that of respective monomer, and it decreas es further for a higher aggregate of bacteriochlorophyll d. Based on t his index, a molecular structure of the primary electron donor in reac tion center complexes is discussed.