Camille Ruf · Public domain

Willstätter won the 1915 Nobel Prize in Chemistry for working out the molecular structure of chlorophyll, showing it was actually a mixture of two closely related pigments — foundational work for understanding how plants convert light into chemical energy. Born into a Jewish family in Karlsruhe, he resigned his chair at Munich at 53 in protest of the university's antisemitism toward Jewish faculty candidates, and afterward directed research only by telephone from home rather than accept another post. He held out in Germany until 1939, when he finally emigrated to Switzerland; he died there in 1942.