1982 PROGRAM 3 (<9 9:
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W 8 2; 5 Eighth Annual SymPOSlum on
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8.30 CoffeeChemistry-Physics - scuss on an 0 cc rea m E g emlstl'y an
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10:45 CHLOROPHYLL FUNCTION IN 9 Q (7; Molecular Biolo
9:00 Welcome and Introduction NATURAL AND ARTIFICIAL 8 5 9y
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
% E".
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