Hans Kuhn

Hans Kuhn ( born December 5, 1919 in Bern, † November 25, 2012 ) was a Swiss professor of Physical Chemistry and Director at the Max Planck Institute for Biophysical Chemistry (Karl Friedrich Bonhoeffer Institute ) in Göttingen.

Life

Hans Kuhn studied chemistry at the ETH Zurich and received his diploma as engineer - chemist. He then went to the University of Basel, where he Dr. phil. doctorate and habilitation in 1946. 1946-1947 he worked as a post-doctoral researcher at the Linus Pauling at the California Institute of Technology in Pasadena and 1950 for a few months with Niels Bohr in Copenhagen. Hans Kuhn in 1951 professor at the University of Basel. In 1953 he was appointed Professor and Director of the Institute for Physical Chemistry at the University of Marburg. From 1970 to 1985 he was Director of the Department " Molecular System Design " at the Max Planck Institute for Biophysical Chemistry (Karl Friedrich Bonhoeffer Institute ) in Göttingen.

Fritz Peter Schäfer, Peter Fromherz, Horst -Dieter Försterling, Viola Vogel and Dietmar Möbius were students of Hans Kuhn; Erwin Neher was an assistant in his department. The marriage with Elsi Hättenschwiler was 1948, she gave birth to the children Elisabeth, Andreas, Eva, Christopher. Elsi died 2004.

Theses

Hans Kuhn began his doctoral thesis to investigate the disentanglement of chain molecules in flowing solution. Werner Kuhn suggested to him to replace the chain molecule to simplify the theoretical treatment by a dumbbell model. Hans Kuhn was fascinated by the simplicity and the success of the model in the quantitative analysis of a variety of experiments. This experience, supported by the work of Linus Pauling and Niels Bohr who was determinative of the life - work of Hans Kuhn in research. Polymers were first described in 1934 by Werner Kuhn statistical chain thread elements. In 1943, the statistical preference element is defined. It is now called the Kuhn length. In the textbook "Principles of Physical Chemistry" it is called " statistical chain element ". To more accurately describe the behavior geknäulter chain molecules than by the dumbbell model, Hans Kuhn made ​​to macroscopic models of molecular tangles and examined their hydrodynamic behavior.

In Pauling he tried the absorption of polyenes by the electron gas model to explain what did not work. Two years later, he saw that the model applied to cyanine dyes, led to a quantitative agreement of the expected spectra with experiment. He saw the reason of his failure at the polyenes is that in assuming equal bond lengths, an instability occurs, which leads to an alternation between single and double bonds, caused by the condition of self- consistency between the assumed bond lengths and calculated π - electron density distribution. The only way he could understand the absorption spectra of polyenes. Later, the assumption was theoretically justified. This effect is often referred to as Peierls instability: starting from a linear chain of atoms equidistant turned Peierls to a first order perturbation theory with Bloch wave functions, but it did not show the self-consistency, which leads to the alternation of single and double bond. The special properties of conducting polymers are based on the theoretical relationship between bond length and bond -length equalization. The electron gas model and its refinements developed into a theory of light absorption of organic dyes. In Marburg, Hans and Fritz Kuhn Peter Schäfer developed ( just before the era of the digital computer ) an analog computer for solving the two-dimensional Schrödinger equation. This space-filling machine was used by the research group of Hans Kuhn to calculate the bond lengths interesting π -electron systems.

Beginning of the 1960s, thought Hans Kuhn to a new paradigm in chemistry, the synthesis of different molecules that are structurally fit into each other so that they are functional components, ie the form as a whole a pre-planned functional unit, a supramolecular machine. His group is constructed prototypes of such machines. Developing new techniques for the production and manipulation of Langmuir- Blodgett films They are now known as the Langmuir-Blodgett layers Kuhn ( LBK- layers ) or as LBK films. The many new methods have been developed in close collaboration with Dietmar Möbius and should therefore be referred to as Langmuir -Blodgett -Kuhn - Möbius layers ( LMBK layers).

Closely related to the problem of the formation of supramolecular machines on the question of the origin of life. Hans Kuhn understood his contribution in the search for a theoretically consistent and chemically plausible way out of many successive physico- chemical steps leading to a genetic apparatus. The process itself is consistent with thermodynamics. The life - emergence is not a particular problem of thermodynamics. Certain steps in the understanding of its mechanism particularly significant as the shift from a duplication translation apparatus to a reproduction transcription- translation system. In this image must, in the attempt to understand the origin of life, the imagination and skill of the experimenter to be replaced in the formation of supramolecular machine through a special random environment at a very special place on the prebiotic earth and elsewhere in the universe that the process drives. The unifying paradigm has led simple supramolecular machines for construction and for finding a theoretically consistent way to an apparatus that matches the basic mechanism with the genetic apparatus of biology. This required a simple conceptual models for describing complex situations. In the further development in different laboratories important new experimental methods have been invented and developed, which led to a divergence: supramolecular chemistry, molecular electronics, Systems Chemistry and important contributions to nanotechnology. It is stimulating and useful to have the link of this pioneering areas in mind. In a modern textbook of physical chemistry should be included.

After his retirement, Hans Kuhn developed with his son Christopher and Horst -Dieter Försterling his early work on electron density and bond lengths, a predecessor of the " density functional theory " (DFT ), consistent with a bond length of π - electron density BCD Method on. He contributed to the understanding of photosynthesis of purple bacteria, the proton pump of halobacteria and the ATP synthase motor.

Awards

Writings

• The Electron Gas Theory of the Color of Natural and Artificial Dyes. by Hans Kuhn in Progress in the Chemistry of Organic Natural Products ed Laszlo Zechmeister 16, 169 (1958 ) and ibid. 17, 404 (1959).
• Practice of physical chemistry. Fundamentals, methods, experiments by Horst -Dieter Försterling and Hans Kuhn, 3rd Edition, Wiley -VCH, Weinheim (1991) ( ISBN 3-527-28293-9 ).
• Monolayer assemblies. In Investigations of Surfaces and Interfaces by Hans Kuhn and Dietmar Möbius in Physical Methods of Chemistry Series eds. Bryant William Rossiter and Roger C. Baetzold, Part B, Chapter 6, Vol 9B, 2nd Edition, Wiley, New York ( 1993).
• Principles of Physical Chemistry by Hans Kuhn, Horst -Dieter Försterling and David H. Waldeck, 2nd Edition, Wiley, Hoboken ( 2009) ( ISBN 978-0-470-08964-4 )