A co-recipient of the 2021 Wolf Prize, Israeli scientist – a former South African – solves a 140-year-old complex riddle
By David E. Kaplan
Israel’s prestigious Wolf Prize – an annual international award given to outstanding scientists and artists from around the world – have been handed out for the past 43 years to 354 leading scientists and artists including Israel’s Prof. Ada Yonath, who won the Nobel Prize for chemistry in 2009. To this illustrious list, we can now add the 2021 recipients, that includes a former South African, Prof. Leslie Leiserowitz who with his longstanding collegial partner Prof. Meir Lahav, both of the Weitzman Institute’s Molecular Chemistry and Materials Science Department for their collaborative establishment of the ”fundamental reciprocal influences of three-dimensional molecular structure upon structures of organic crystals.”
Awarded for “achievements in the interest of mankind and friendly relations among people … irrespective of nationality, race, colour, religion, sex or political views,” there is no doubt that Leslie and Meirs’ scientific discoveries have truly contributed towards “the interest of mankind and friendly relations among people”.
They have at the same time solved a riddle!
Resolving a Riddle
Crystal formation is one of the most fundamental phenomena in chemistry and the structure of organic crystals is of particular importance because the crystal shape (morphology) reflects the three-dimensional structure (stereochemistry) of the molecules assembled in that crystal. In 1848, the famed French chemist microbiologist. Louis Pasteur conducted his famous experiment, physically separating the two crystalline forms of a tartaric acid salt, which mirror one another. Pasteur’s experiment became the basis for modern stereochemistry, and it was followed by the study of the first Nobel Laureate in Chemistry, Jacobus H. van’t Hoff from Holland. However, neither Pasteur nor van’t Hoff, nor many of the other famous chemists that followed would come to understand the relationship between crystal morphology and molecular stereochemistry until 140 years had passed and two Israelis, Professors Lahav and Leiserowitz conducted their milestone experiments in the Mid-1980s. These experiments demonstrated for the first time that the absolute configuration of molecules can be derived from their crystal morphologies. They not only solved the long-standing puzzle; but according to the Wolf Foundation press release:
“they also pioneered the science of organic crystals’ stereochemistry. They directly related the stereochemistry of the individual molecule to the shape of the macroscopic crystal. They founded the links between molecular structure, crystal morphology, crystal growth’ dynamics, and molecular chirality (the structural property of an object, which makes it different from its mirror image, like the human hands). Their findings laid the foundation for our current knowledge of the selective self-assembly of organic molecules. In this way, their rules powerfully complement our understanding of organic chemistry for covalent assembly and macromolecules’ self-assembly.”
When Prof. Leslie Leiserowitz was awarded the 2016 Israel Prize for ‘Chemistry and Physics’ with Prof. Meir Lahav, he was only the third South African Israeli to receive Israel’s highest civilian award. The other two recipients had been Dr. Ian Froman in 1989 for his contribution to society through sport, and the late Hillel Deleski in 2000 for the study of English literature.
Interviewing Leiserowitz at the time, he explained to me by posing these questions:
“How and why do artery-blocking chunks of cholesterol form?”
“What happens at the very first stage of the transition from water to ice?”
“What can be done to prevent the formation of gallstones or the crystals in the joints that cause pain in gout?”
These are all questions about one of the more important processes in nature: crystallization, and Leslie and Professor Lahav have worked separately and together over their careers to investigate this process.
Indebted to Mom!
Born in Johannesburg in 1934, Leslie obtained a BSc. in Electrical Engineering from the University of Cape Town (UCT) and during an ensuing 18-month period “of work, unemployment and travel,” he became fascinated in a field of chemistry that drew him to an illuminating work – “The Crystalline State” by Brag & Bragg. “The symmetry of the crystal structures therein,” intrigued Leslie, reminding him “of the patterns my mother worked with as a dressmaker in Johannesburg.”
This curiosity, coupled with a knowledge of “microwave interference”, led him to his next marker on his academic path – “The Optical Principles of the Distraction of X-rays” by R.W. James, who was Professor of Physic at UCT. With now a clear direction, the young budding scientist studied for an MSc in X-ray crystallography in the Physics Dept. at UCT.
Following his travels to London and then on to Israel “with my good friend”, the future South African Jewish leader Mervyn Smith, who he knew “from our Bellville days,” he joined in 1959, the research group of Gerhard Schmidt at the Weizmann Institute of Science as a PhD student in solid-state chemistry.
Leslie’s journey of research, took him to academic posts abroad, and in more recent years, focused on a childhood fascination with the study of malaria – a project, which he says, “in some ways is a continuation of my original research with Prof. Lahav on crystal growth. It was not generally appreciated that this infectious disease is intimately connected with crystallization.” Leslie reveals that growing up in Johannesburg, “I learnt from my father, who had spent long stretches of time in Central Africa, the full ravages of the disease.”
It was an area of study that Leslie felt compelled to study and most assuredly gels with the spirit of the wording of the Wolf Prize of contributing towards “the interest of mankind and friendly relations among people”.
If Leslie’s mother, who died young – “only in her forties” – was today looking down from her celestial perch, she would be amazed and proud that from the simple patterns of her daily dressmaking, lay the complex mysteries that would inspire her brilliant son to pursue a journey of scientific exploration culminating in the 2016 Israel Prize and the 2021 Wolf Prize.
Maybe, she had a “crystal ball”, and foresaw it all coming!
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