Hans Kuhn (5 December 1919 – 25 November 2012) was a Swiss chemist. He was professor emeritus for physical chemistry and former scientific director at the Max Planck Institute for Biophysical Chemistry (Karl Friedrich Bonhoeffer Institute) in Göttingen. Biography Curriculum Hans Kuhn was born in Bern, Switzerland. He studied chemistry at the ETH Zürich and worked for his doctorate at University of Basel under the guidance of Werner Kuhn (not related). He received his habilitation in 1946. From 1946 until 1947 he worked as a post doctoral fellow with Linus Pauling at Caltech in Pasadena and in 1950 with Niels Bohr in Copenhagen. In 1951, he became professor at the University of Basel. He was appointed in 1953 as professor and director of the Institute of Physical Chemistry of the Philipps University of Marburg where he stayed until 1970. Then he was at the Max Planck Institute for Biophysical Chemistry (Karl Friedrich Bonhoeffer Institute) in Göttingen as director of the department 'Molecular Systems Assembly' until his retirement 1985. Fritz Peter Schäfer, , Horst-Dieter Försterling, Viola Vogel and Dietmar Möbius were among Kuhn's students. Erwin Neher was member in his department 'Molecular Systems Assembly'. Kuhn married Elsi Hättenschwiler 1948. Their four children were Elisabeth, Andreas, Eva and Christoph. Elsi died 2004. Scientific research Kuhn began to work for his doctorate by investigating decoiling of a random coiled chain molecule in a flowing viscous solvent. Werner Kuhn suggested him to replace the random coil by a dumbbell-model. Kuhn was fascinated by the model's simplicity and by its great success in theoretically analyzing a broad variety of experiments in quantitative terms. This experience and his postdoctoral work with Linus Pauling and Niels Bohr, supported this fascination for powerful simple models and was determining for his life's work in research. Polymer molecules were described as chains of statistical chain elements. The preferential statistical elements were defined in 1943. Today the preferential element is called Kuhn length, in the recent textbook Principles of Physical Chemistry it is simply called statistical chain element. Kuhn made experiments with macroscopic models of random coils to describe the behavior in flowing liquids more accurately than based on the dumbbell-model. In Pauling's lab, Kuhn was trying to understand the color of polyenes by describing π-electrons as particles in a box and he was greatly disappointed - it did not work. Later, when applying the model to cyanine dyes he observed