Red Chlorophyll

Main approach to the problem of utilization of solar energy has been study of green plants, which in their own simple and mysterious way utilize the energy of sunlight to convert carbon dioxide and water into food. Chief agent in this process of photosynthesis is chlorophyll, the green coloring-matter in leaves, which acts as a catalyst, speeding up the transformation, but undergoing no conversion itself. Since chlorophyll is not effective as a catalyst when extracted from the plant, chemists have been unable to study its action. It is composed of two separate pigments, blue-green chlorophyll A and yellow-green chlorophyll B, whose atoms of carbon, hydrogen, and nitrogen are arranged in rings similar to that of the red pigment in human blood corpuscles. Main difference between the chemical composition of chlorophyll and the coloring matter of blood cells is that the former contains magnesium, the latter iron.

In 1935 the chlorophyll ring systems, called porphin,* were synthesized by German-born Dr. Paul Wilhelm Karl Rothemund of the C. F. Kettering Founadation/- (for study of chlorophyll and photosynthesis) at Antioch College, Yellow Springs, Ohio. Last week at the Milwaukee convention of the American Chemical Society, brilliant young Dr. Rothemund reported that he had finally "activated" chlorophyll in his laboratory. When chlorophyll is heated in certain organic solvents it exhibits chemiluminescence (radiation at low temperatures): gives off "a beautiful red glow." The magnesium or zinc salts of porphyrins also exhibit chemiluminescence when heated in the same manner. Thus chlorophyll not only absorbs light but somehow transforms it and gives it forth again. At present Dr. Rothemund is trying to "correlate the amount of energy dissipated by this radiation to the amount of chlorophyll decomposed, and the energy required to start the process of chemiluminescence."

* From the Greek porphyrcos, meaning purple. When porphyrins (porphin substances) are dissolved in ether they turn purple-red.

/- Endowed by Charles Franklin Kettering, Vice president of General Motors.

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