Complex sentence: He followed Bonhöffer to Berlin where his Ph.D. supervisor had accepted the directorship of the Institute of Physical Chemistry at Humboldt University, and also became the department head at the Kaiser Wilhelm Institute for Physical Chemistry in Berlin-Dahlem (later the Fritz Haber Institute).
Split into simpler sentences: He followed Bonhöffer to Berlin where his Ph.D. supervisor had accepted the directorship of the Institute of Physical Chemistry at Humboldt University. There he also became the department head at the Kaiser Wilhelm Institute for Physical Chemistry in Berlin-Dahlem (later the Fritz Haber Institute).