FranÅois Diederich (1952–2020): 40 Years of Organic Chemistry FranÅois Diederich was born in Ettelbrück, Lux- embourg, on July 9, 1952. Like so many Luxem- bourgers, he attended the University of Heidelberg, in his case studying chemistry. He received his PhD in 1979 at the Max Planck Institute for Medical Research, working with Heinz A. Staab on Keku- lene (Figure 1 A). [1] The synthesis and study of this unusual compound was important in the context of probing aromaticity concepts. FranÅois Diederich succeeded in synthesizing the molecule, using a novel high dilution apparatus designed by Fritz Vçgtle. For the measurement of NMR spectra, Kekulene was dissolved in [D 3 ]-1,3,5-trichloroben- zene at 215 8C, and single crystals for X-ray diffraction analysis were obtained by recrystalliza- tion from pure liquid pyrene. [1, 2] A central point in this endeavour of exploring the boundaries of aromaticity [3] was the question of whether the unusual molecule consists of fused benzene rings (benzenoid structure), or if larger p-conjugated perimeters develop along the outer and inner rims of the molecule (annulenoid structure, Figure 1). NMR spectroscopic evidence and computations eventually showed that the description of Kekulene as a fused “multi-benzene” is probably most accurate. After a postdoctoral stay in the group of Orville L. Chapman (1979–80) at the University of California, Los Angeles (UCLA), FranÅois Diederich returned to Heidelberg in 1981 to establish a junior research group at the Max Planck Institute for Medical Research. There he habilitated in 1985. It was the great era of supramolecular chemistry, marked by the award of the 1987 Nobel Prize in Chemistry to three pioneers in the field, namely Donald J. Cram, Jean- Marie Lehn, and Charles Pedersen. [7–9] FranÅois Diederich was one of the first to investigate the molecular recognition of hydrophobic compounds in water. The Diederich group prepared preorgan- ized water-soluble cyclophanes with ammonium substituents and a hydrophobic inner cavity as molecular hosts (Figure 1B). Based on work of Koga et al., [6] these receptors were able to effec- tively complex aromatic molecules, some of them by exploiting cation–p interactions, amongst others. [10] A large enthalpic driving force was found for the complexation of apolar guests by cyclophanes in water (enthalpic hydrophobic effect). [11] At the time when FranÅois Diederich com- pleted his habilitation, vacant academic appoint- ments were rare in Germany. In 1985, he decided to pursue his career as a Visiting Associate Professor at UCLA. There, he benefitted from the support of Donald J. Cram, quickly moved through the ranks Figure 1. A) Kekulene with benzenoid and annulenoid structure. [1] The lack of a massive upfield shift for the inner protons (d = 10.45 ppm; 80 MHz, [D] 3 -1,3,5-trichlorobenzene, 215 8C) indicates the absence of a macrocyclic ring current. B) Water- soluble cyclophane receptors by F. Diederich, [4, 5] the design of which was inspired by the first hosts for the complexation of hydrophobic molecules in water (K. Koga). [6] Angewandte Chemie Obituary 11562  2021 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Angew. Chem. Int. Ed. 2021, 60, 11562 – 11567