Meeting report

Leiserowitz still cutting edge

Leslie Leiserowitz was honored on his 65th Birthday with a symposium at the Weizmann Institute of Science. Leslie has consistently demonstrated the ability to identify challenging problems and the tenacity to find satisfying rational explanations. Speakers, P. Coppens, J. Als-Neilson, A, Gavezzotti and J. M. McBride described how Leslie's career, advice and collaboration had aided and inspired them in their careers. In his introductory remarks, M. Lahav said that when Leslie arrived at the Weizmann from South Africa he immediately applied the then very new Hauptman-Karle Method to a structure determination and characterized an interaction in a crystal structure that he felt demonstrative of a CH...O hydrogen bond. Philip Coppens described how he, Leslie and D. Rabinowitz began the very first charge density study using the Weissenberg camera that G. Schmidt brought to the Weizmann. Philip also described his latest studies using synchrotron radiation to examine electron density in the excited states of molecules. He identified as suitable candidates for this new technology; molecular excited states, photochemical electron transfer, and long-lived charge separated excited states and stressed the need for a national facility for time resolved X-ray diffraction.

Jens Nielson described state of the art studies of two-dimensional crystals generated in his elegantly designed Langmuir trough. Leslie and Jens are collaborating on experiments to probe formation of cholesterol crystals beginning with monolayers and elaborating on them. Angelo Gavezzotti has gained tremendous insight into the principles of molecular aggregation from the wealth of data in the CSD, but still finds the prediction of structure fraught with difficulty. He is exploring the insights that can be gained from dynamic calculations. Gavezzotti finds that dozens of crystal form of nearly equal energy are predicted for most single molecules, while only one form is usually crystallized. Coppens and Gavezzotti expressed concern that they were studying problems that were highly important but might not be solved in their lifetime. O. Livnah presented another puzzle with his obsesrvation that peptides of essentially random sequence induced aggregation of the erythropoitem receptor when rationally designed peptides failed to do so.

Mike McBride was pleased to find himself on the young people's portion of the program with Livnah and I. Sagi who showed wonderful electron micrographs of RNA helicase with clear, separate strands of DNA. Sagi seemed delighted to announce that she was too young to have any anecdotes about Leslie's early years.

McBride, closing the symposium with four great talks in one including a video of the dissolution of crystals, a walk in the sands of Palmore, and demonstration that a cleavage plane in a hydrogen bonded crystal will be parallel to the family of planes that intersects the fewest H-bonds.

At a dinner for friends, family and students, Leslie demonstrated his exceptional talents as a devoted grandfather and the Master of ceremonies, Bill James (U. Cambridge) reminisced about his sabbatical at the Wiezmann.

William L. Duax