Jack David Dunitz (1923-2021) and chemical crystallography.

Attempting to appreciate Jack’s merits in science runs the risk of bias. This danger can be minimized, however, by listening to Jack’s own words. In an essay entitled ‘La Primavera’ (Dunitz, 2013), Jack reflects on his formative years, the time before he took his position at ETHZ in 1957; in 2021 Jack looked back on his long life in science in two interviews conducted by E. Carreira, his colleague at ETHZ and editor-in-chief of the Journal of the American Chemical Society; Jack’s relationship vis-à-vis molecular biology is the theme of a conversation with E. Carafoli conducted in 2017 (Carafoli, 2017); in the journal Chimia Jack chats about exploring the world of science, his wanderings and his life in Zürich, inside and outside of ETHZ (Weber, 2011). This account attempts to portray Jack’s most important achievements against the background of concepts and activities prevailing during the time of his involvement in science. Hargittai (2021) writes in a similar vein. Jack was born on 29 March 1923 in Glasgow (Scotland) where he grew up into the golden age of X-ray and chemical crystallography. During his education his high school teacher got him interested in the sciences and World War II brought him to the group of the renowned crystallographer J. Monteath Robertson to do PhD research. He learned the art and science of structure determination: art because structures like the ones Jack worked on, with H, C and O atoms only, had first to be guessed at; direct methods had not yet been invented; science to the extent there were systematic heavy atom methods such as the Patterson method and the isomorphous replacement method, the latter invented by his supervisor. After gaining his PhD in 1944, his journeyman’s years had him work with actual and future Nobel laureates, Dorothy Hodgkin in Oxford, Linus Pauling at ISSN 2052-5206