Issue Date: October 20, 2014
It’s A Hit: X-Ray Crystallography
I found the cover story “100 Years of X-ray Crystallography” most fascinating (C&EN, Aug. 11, page 32). But I think the Jack Dunitz-H. B. Bürgi paper deserves at least a mention (J. Am. Chem. Soc. 1973, DOI: 10.1021/ja00796a058). It was the first time that a reaction path had been discovered by X-ray, a method normally expected to give information only on static systems.
The Dunitz-Burgi approach also led to a better understanding of 1,2-asymmetric induction and cyclization reactions (Baldwin’s rules).
Nguyen Trong Anh
The cover story on crystallography is a marvelous piece of journalism and riveting reading, at least to older generations of chemists. What stands out is the tingling thrill of discovery and the convolutions of thought of what would have happened if there had been slight turns of events and selective available knowledge.
More apropos to our times, the various articles show how chemistry was a more freewheeling activity. Imagine the consequences today if an editor wrote to an author—as quoted in the ferrocene article—that “I cannot help feeling that you have been at the hashish again.” This raises the question: Will such splendid documentation exist from the commentaries and anecdotes on current discoveries that are disappearing with one tap of the delete key?
Kingston, , Ontario
I don’t know when I’ve enjoyed an issue more than the one featuring X-ray crystallography. I am a structural chemist, and although X-ray crystallography has not been my primary research tool (that is gas-phase electron diffraction), I have maintained a steady interest in the technique since my graduate school and postdoctoral years at Caltech of about a decade beginning in 1946.
I knew about much of the early work in crystallography, but I particularly enjoyed reading about the good friends I met during my time at Caltech—Alex Rich, Jack Dunitz, Leslie Orgel, and Ken Trueblood, among others—whose contributions were yet to come.
The decade I mention was immensely exciting. Physical chemistry at Caltech was, of course, dominated by the interests of Linus Pauling, who was very active in working out the structures of the proteins he is credited with and whose fame led to visits by prominent foreign crystallographers. Pauling was a most persuasive man, which led to the cost-free installation of a group of IBM office machines that greatly sped up the vast amount of calculation still done in most labs by Beevers-Lipson strips and hand calculators.
I recall seeing a letter from Max Perutz, written from England in 1946, asking Pauling if he could arrange for someone to do a Patterson synthesis, because, “although there exists a Hollerith machine in this country, there is no organisation whereby it could be put at the disposal of crystallographers.” Pauling’s reply was, in effect, that there was no one at Caltech who could afford to spend the time required but that Perutz would be welcome to have use of the machine if he could come himself or send someone to do the work.
Finally, a few observations about Dorothy Hodgkin, whom I was privileged to meet on several occasions. Dorothy, as she seemed to prefer to be addressed, wore her fame invisibly. I remember her as a very good listener who enjoyed interactions in small groups that even included drinking a beer from a bottle with the rest of us. As nearly everyone knows, Dorothy was sorely afflicted with steadily worsening rheumatoid arthritis.
My last contact with her was at an outdoor banquet during a meeting of the International Union of Crystallography, in Canada. I assisted her with her plate of food down a grassy slope to a picnic table. With her crippled hands she was unable to cut her meat, so I offered my help. Thanking me, she accepted without embarrassment, apology, or complaint about her condition. A remarkable woman, indeed.
I thoroughly enjoyed the issue of C&EN celebrating the 100-year anniversary of crystallography, especially since I was fortunate to have had a formal crystallography course at the University of Southern California, taught by Jerry Donohue, and also since I was able to continue to be involved in crystallography my whole professional career.
Reading the section on the description of the James D. Watson and Francis H. C. Crick unraveling of the structure of DNA, I thought that a rather significant piece of the puzzle was omitted. Donohue, a student of Linus Pauling’s, received a Guggenheim Fellowship to study at Cambridge University, and he shared an office with Watson and Crick. Donohue provided critical evidence to Watson that he was using the wrong form of the base pairs for his model.
Following is a section from a biography of Donohue:
“In his work to determine the structure of DNA, Watson had been using structure for guanine from a monograph by James N. Davidson. Davidson had depicted these bases in the enol configuration and Watson used this structure in an unsuccessful ‘like-with-like’ pairing of the bases. Donohue informed Watson that the published structure was just a guess and that the keto structure was more likely, based on a publication of June Broomfield and quantum mechanical calculations. Within a few days, Watson and Crick were able to build their famous model for DNA.”
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