* 1982 PROGRAM 3 (<9 9: -1 . . W 8 2; 5 Eighth Annual SymPOSlum on .3 < g 5 9~ 3 . 3: m A:' 1015 m i ac ff B k 89 0 Ch d 8.30 CoffeeChemistry-Physics - scuss on an 0 cc rea m E g emlstl'y an Rm. 137 O n 3 10:45 CHLOROPHYLL FUNCTION IN 9 Q (7; Molecular Biolo 9:00 Welcome and Introduction NATURAL AND ARTIFICIAL 8 5 9y Rm. 139 PHOTOSYNTHESIS tn" 9:15 ARTIFICIAL Dr. Joseph J. Katz PHOTOSYNTHESIS: Chlorophyll is the indispensable agent . . SYNTHETIC CHLOROPLASTS for light energy conversion in green plant eStabllShed m the memory Of and bacterial photosynthesis, and a de- Anna S. Naff tailed understanding of how it functions D" Melvin Calvin in natural photosynthesis would do much Knowledge of the mechanism of pri- to facilitate the development of artificial __ mary energy capture and conversion by photosynthesis. The chlorophyll mole- green plant chloroplasts is used to guide cule, it now becomes evident from vari- ARTIFICIAL the design of artificial systems for conver- ous lines of physical investigation, has an sion and storage Of solar energy. Ah es- unusual combination of coordination sential function to be imitated is the con- properties. These coordination interac- pHOTOSYNTHESIs version of absorbed light energy by tions between chlorophyll and other charge separation in an oxidation-reduc- chlorophyll molecules and with various tion reaction, and the prevention of back chloroplast components now make it pos- reaction between the charged oxidized sible to consider Specific molecular S eakers electron donor and reduced electron ac- structures for the different species of P ceptor. We have achieved this goal in two chlorophyll present in chloroplasts and ways: (1) The phototransfer of an electron bacterial chromatophores. Model sys- across an insulating lipid layer between terns can now be fashioned in the labora- tWO separated aqueous phases, one con- tory that mimic many of the features of PROF. MELVlN CALVIN taining the donor and the other the accep- natural photoreactive chlorophyll, and tor. (2) The use of small particles, either rudimentary antenna-reaction centers for DR JOSEPH J KATZ "Pld vesicles or silica particles, With a the study of energy transfer are also now high negative surface charge density. The available, These models, and the ways in . sensitizer adheres to the particles, where- which they can contribute to the under- as the negatively charged reduced accep- standing of natural photosynthesis, will tor is repelled into the continuous phase be described. - after electron transfer. The separation of April 30 1982 , products thus achieved has led to a great Department Of ChemIStry increase in quantum yield, as high as 2 University of Kentucky 30%. Ways are now being sought to use 5 g L . K k 40506 catalytic reactions (such as occur in na- e g. C :1 exmgton, entuc y ture) to bring about the oxidation and re- g 5* in % duction of water to hydrogen and oxygen. 7" 5 0:3 5 gamma % E". < o _ :l