In Memoriam Johan Lugtenburg
The fastest chemical reaction in the universe takes place inside our eyes.
On 15 September 2023, at the age of 81, Prof. Dr. Johan Lugtenburg, emeritus professor of organic chemistry, in particular bio-organic photochemistry, and Knight of the Order of the Dutch Lion, passed away. Born during the war in Nieuwenhoorn, on Voorne-Putten, after graduating from HBS, he went to Leiden to study chemistry, at the Hugo de Grootstraat. There he became the chemist in heart and soul that many, in Leiden but also nationally and internationally, have come to know as an exceptional scientist, an exceptional human being, and above all an amiable person, who never stood in anyone's way and was always willing to lend a helping hand. He studied and obtained his PhD with Prof. Egbert Havinga on photochemical research on vitamin D.
After his PhD, he left for San Diego in the United States. There he thought, sitting on La Jolla beach and looking at the sun, that he wanted to dedicate his life to researching and understanding the chemistry of vision, the visual process by which we perceive our surroundings. The molecule at the centre of this is the membrane protein rhodopsin containing the vitamin A that traps light as a retinylidene-protonated Schiff base. Through a photoisomerisation and a linked structural change, it triggers the cascade of protein processes that generate the signals in the body and in the brain that allow us to see.
Very soon, his name and fame became widespread in chemistry. With great dedication, he and his students and post-docs worked out the total-synthesis of vitamin A step by step, with high yields, to apply stable isotopes at every spot in the molecule. This enabled highly sensitive optical vibrational spectroscopy and NMR experiments to be performed, in international, world-wide collaborations that over decades have provided a unique stream of fundamental data on what he himself pronounced as "I am investigating the fastest chemical reaction in the universe, mind you!" Vitamin A isomerisation was found to be completed in less than 200 femtoseconds, making it a very fast indeed, and possibly the fastest reaction observed by chemists. This could not be explained by existing chemical theories, and the interpretation required the development of new theory based on quantum-coherent processes that, as it later turned out, could be applied to many more subfields of chemistry. During his long career of more than 45 years in chemistry, Johan contributed to this with more than 400 scientific publications, and his work is internationally recognised as being of the highest level in the field.
Almost everyone in Dutch organic chemistry knew Johan, as a flamboyant chemist, certainly also a bon vivant, but above all as an excellent, talented scientist, an erudite human being, who made a unique, independent and idiosyncratic contribution to the development of chemistry as a discipline. The LIC remembers him and we are grateful for what he contributed to education and research in Leiden Chemistry, in adjacent research areas in the pharmaceutical and medical disciplines and in collaborations with industry. We will permanently remember how it was always a pleasure to be addressed by him, to be taught about the position of the stars and planets of the moment, the course of history during and after the Second World War and how it could have turned out differently if basic mistakes had not been made by political personalities, or simply to have a chat with him about what was close to his heart, and that was a lot because he had an invaluable opinion about everything.