- Person
- Richard Willstätter
- Lived
- 1872–1942
- Field
- Organic chemistry
- From
- German
The story
Chlorophyll is the molecule that makes leaves green and allows plants to turn sunlight into food. Yet at the start of the twentieth century it was poorly understood. It is fragile, hard to purify and easily altered, and earlier chemists had produced contradictory results. Magnesium had already been detected in chlorophyll, but no one knew whether it was a real part of the molecule or merely an impurity.
Richard Willstätter had begun studying chlorophyll in Munich, but the laboratory there was too limited for the task. In 1905 he became professor of chemistry at the ETH in Zurich, and the seven years that followed were, in his own view, the best and most significant of his career. With his students he developed careful methods to extract chlorophyll without changing it or introducing impurities, and he determined its empirical formula.
He showed that magnesium was not an accidental impurity but an essential component of the molecule. It sits at the centre in a way very similar to how iron sits at the centre of haemoglobin, the oxygen-carrying pigment of blood. He identified chlorophyll as a magnesium complex of a porphyrin-type structure, part of which is linked to a long-chain alcohol called phytol, and by breaking it down step by step with acids and alkalis he produced a series of well-characterised intermediates. After moving to Berlin in 1912 he rounded off the chlorophyll work and completed related studies of haemoglobin.
In 1915 Willstätter was awarded the Nobel Prize in Chemistry for his researches on plant pigments, especially chlorophyll. Because of the First World War, he could not travel to Stockholm until 1920, when he gave his Nobel lecture, On Plant Pigments, on 3 June and joined a ceremony for several laureates honoured during the war, among them Max Planck and Fritz Haber.
His findings laid the chemical foundations for later understanding of photosynthesis. The complete structures of chlorophyll and haemoglobin were later worked out by Hans Fischer, work that would not have been possible without Willstätter's pioneering research. His work also revealed a deep chemical kinship between the green pigment of plants and the red pigment of blood.
Why it matters
Knowing what chlorophyll is made of was a vital step toward understanding photosynthesis, the process that feeds nearly all life on Earth and fills the air with oxygen.
About Richard Willstätter
Nobel-winning chemist who unravelled chlorophyll and the colours of flowers, refused to convert, resigned his chair in protest at antisemitism and died a refugee in Switzerland.
More about Richard Willstätter
- Richard Willstätter helped explain why carrots are orangeWhile purifying chlorophyll, Richard Willstätter found yellow by-products that turned out to be carotenoids, beginning the scientific study of the pigments in carrots, tomatoes and egg yolks.
- Richard Willstätter decoded the colours of flowersRichard Willstätter discovered that most red, purple and blue flowers owe their colour to three related pigments, and that acidity or alkalinity in the sap helps decide the shade.
- Richard Willstätter discovered chlorophyll a and bAfter studying chlorophyll from more than 200 kinds of plants, Richard Willstätter showed it is always a mix of two pigments, chlorophyll a and chlorophyll b, in a ratio of about three to one.
- Richard Willstätter corrected the structure of cocaineAs a young doctoral student in Munich, Richard Willstätter showed that the accepted chemical structure of cocaine was wrong, launching his career in the chemistry of plant alkaloids.
- Richard Willstätter made a molecule that tested a theoryRichard Willstätter synthesised cyclooctatetraene, a ring of eight carbon atoms, and showed it does not behave like benzene, an important test of ideas about chemical stability.
- Richard Willstätter treated enzymes as chemicalsIn the 1920s Richard Willstätter developed methods to purify enzymes and helped establish that they are chemical substances that can be studied with the tools of chemistry.
- Richard Willstätter built a gas mask filter in five weeksRefusing to work on poison gas, Richard Willstätter instead designed a protective gas mask filter in about five weeks in 1915, shielding soldiers from chlorine and phosgene.
- Richard Willstätter resigned to protest antisemitismIn 1924 Richard Willstätter gave up one of Germany's most prestigious chairs of chemistry in protest after his Munich colleagues refused to appoint a scientist because he was Jewish.
Sources
- Richard Willstätter Encyclopedia.com
- Richard Willstätter Wikipedia
- Richard Willstätter: Biographical NobelPrize.org
Another act of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.