Dedicated to Prof. Dr. rer. nat. Ju ¨rgen Caro on the occasion of his 70th birthday This essay looks back at the three stations of Ju ¨rgen Caro's career, starting with his time as a diploma student of Chemistry (1974)(1975) and PhD student in the NMR laboratory (1975)(1976)(1977) at the University of Leipzig, followed by his stay in Berlin at the Central Institute of Physical Chemistry and, afterwards, the newly founded Institute of Applied Chemistry and, finally, his appointment as full professor for Physical Chemistry at the Hannover University. The focus is on some of the results of our collaboration, including the use of PFG NMR and microimaging for in-situ observation of diffusion in nanoporous materials and the useful application of these findings in the production of high-performance membranes. Reference is also given to joint activities in science organization such as in European research networks and the Diffusion Fundamentals conference series of the Saxon Academy of Sciences and Humanities.