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Professor Hans Freeman speaking at ICBIC-11 in Cairns, 2003. Photo courtesy of Professor Grant Mauk, UBC

Emeritus Professor Hans Freeman, who passed away peacefully on 9 November 2008, was a pioneer of biological inorganic chemistry and of many of the methods used in its study. His many impacts on our field are owed to a number of groundbreaking studies and to his support for the development and use of these new technologies.

Hans began his career studying physical organic chemistry with Raymond Le Fevre, but following the completion of an M.Sc. he decided on a career in crystallography and bioinorganic chemistry. In 1952–1953 he spent a year at Cal Tech working with Eddie Hughes and was greatly influenced by his interactions with Linus Pauling. On his return to Sydney, he collected and built sufficient crystallographic equipment to allow him to complete the structure of biuret hydrate, the subject of his PhD. The structure of copper biuret followed, one of the first bioinorganic structures to be determined. In determining these structures, Hans used SILLIAC, the second computer constructed in Australia. In the following years, Hans and his group determined the structures of many metal complexes of amino acids and peptides, in the process pioneering the use of new developments as they became available.

In 1971–1972, soon after his appointment as the first Professor and Head of Inorganic Chemistry at the University of Sydney, Hans wrote a major review on the structures of metal complexes of peptides and came to the conclusion that it was time to tackle some new challenges. This led to a difficult period as Hans and his group tackled the first protein crystal structures in Australia. His first target was plastocyanin, an intensely blue, copper-containing, electron-transport protein. Plastocyanin was extracted from numerous plant sources, but most failed to give suitable crystals. After a number of years of trying, poplar plastocyanin was found to yield excellent crystals and, with the assistance of recently returned postdocs Peter Colman and Mitchell Guss, the structure emerged in 1977. The unusual geometry around the copper that was revealed by this and subsequent structures has led to a great deal of understanding of the unusual electrochemistry and spectroscopy of the blue copper proteins, much of it emerging from a collaboration with Ed Solomon from Stanford University. Their work on these proteins continues to impact on the field today. The 25th anniversary of the determination of the plastocyanin structure was celebrated at ICBIC-11 in Cairns with a highly entertaining set of presentations from Hans, Mitchell, Ed, and Harry Gray.

Hans’s interest in metalloprotein structure continued up to the time of his passing and the current issue of this journal contains a report of one of his more recent studies. Protein crystallography boomed in Australia following his early work and continues to develop today.

Hans realised in the early 1980s that crystallography alone would not provide the detailed information on metal centres in proteins that was needed to give the level of understanding he sought. He consequently developed an interest in XAFS and other synchrotron-related techniques, again being one of the pioneers of these methods in both Australia and the biological inorganic community. His involvement in the writing of a major report of the Australian Academy of Sciences on access to major research facilities around the world contributed to the establishment of two funding mechanisms that allowed Australians to be become major synchrotron users. It is unquestionable that without these developments, the level of involvement of Australians in synchrotron science would have grown far more slowly and the building of the Australian Synchrotron, opened in 2007, might not have occurred for another decade or more.

Hans’s personal interests in synchrotron science were all in the area of biological inorganic chemistry and he collaborated with many of the senior scientists in this area, continuing a practice he had pursued throughout his career. Hans was a friend, colleague, and collaborator to far more people than can be mentioned here. He was always a delightful host and an enthusiastic organizer of opportunities to talk science and will consequently be sorely missed by a very large part of the biological inorganic chemistry community.