Physical Organic Chemistry in the 21st Century: A Q1 Progress Report by Ian H. Williams
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n 1997, a collection of twenty personal perspectives from eminent chemists was published in Pure and Applied Chemistry to mark the centenary of physical organic chemistry [1]. This Symposium in Print, entitled Physical Organic Chemistry in the 21st Century (POC21C), was organized by the IUPAC Commission on Physical Organic Chemistry, which was chaired at that time by Tom Tidwell, who contributed a historical prologue in which he suggested Stieglitz’s 1899 proposal of carbocations as reaction intermediates as (unwittingly) having given birth to the discipline. The principal authors were Edward Arnett, Daniel Bellus, Ron Breslow, Fulvio Cacace, Jan Engberts, Marye Anne Fox, Ken Houk, Keith Ingold, Alan Katritzky, Ed Kosower, Meir Lahav, Teruaki Mukaiyama, Oleg Nefedov, George Olah, John Roberts, Jean-Michel Savéant, Helmut Schwarz, Andrew Streitwieser, Frank Westheimer, and Akio Yamamoto. Tidwell noted that, whereas they were not all known as physical organic chemists, yet they had all used the tools of this discipline in their work and were able to comment upon the utility of physical organic chemistry for the practice of other areas of chemistry as well. The theme that ran through all the essays was that the future of the field lay in an interdisciplinary approach, that physical organic chemists would use all the tools available to them, and that they would not be fettered to narrow views. A quarter of a century later, it is timely to reflect briefly upon what has happened in the intervening 25 years. Is physical organic chemistry still alive? Does it serve a useful purpose any longer? Have the predicted directions for future research been followed? What unexpected developments have there been?
Glossary of Physical Organic Chemistry 2022 sees the publication in Pure and Applied Chemistry of the Glossary of Terms used in Physical Organic Chemistry (IUPAC Recommendations 2021) [2], a major update of the 1994 version and the result of a lengthy project involving a task group, led by Charles Perrin, under the auspices of the IUPAC Subcommittee on Structural and Mechanistic Chemistry. Besides the redrafting and improvement of entries for many existing terms, the updated Glossary contains numerous new entries. Among these are terms relating to biological chemistry (e.g. catalytic antibody, molecular recognition), computational chemistry (e.g. activation strain model, bifurcation, coarctate),
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Chemistry International
April-June 2022
materials chemistry (e.g. ionic liquid, nanomaterial, photochromism), supramolecular chemistry (e.g. dendrimer, self-assembly), techniques (dynamic NMR, FRET, high-throughput screening), and fundamental concepts (e.g. frustrated Lewis acid-base pair, halogen bond, organocatalysis). The task group was strongly of the opinion that an up-to-date compendium of terms is an essential tool for use by all chemists and not a superfluous extravagance of interest to a small minority. The introduction to the updated glossary includes a pertinent quote from Lavoisier: “Comme ce sont les mots qui conservent les idées et qui les transmettent, il en résulte qu’on ne peut perfectionner le langage sans perfectionner la science, ni la science sans le langage” (As it is words that preserve ideas and convey them, it follows that one cannot improve language without improving science, nor improve science without improving language.”) If this observation was true in 1789, it is certainly no less true today: all interdisciplinary endeavours depend upon clear understanding of language and terminology across whatever disciplinary borders are being crossed.
What’s in a name? During the time of Charlie Perrin’s chairmanship of the Commission on Physical Organic Chemistry, not only did it become a Subcommittee (of IUPAC Division III, Organic and Biomolecular Chemistry), but “physical organic” was replaced by “structural and mechanistic” in its name. Why? Several of the contributors to POC21C had commented to the effect that, as the techniques employed in physical organic chemistry would become generally accepted as the routine way of approaching problems in chemical reactivity, so the need for a special name for a distinct subdiscipline would disappear. The name might be evanescent, but the influence would be transcendent: developments in physical organic chemistry belong to all of chemistry. As structure and mechanism are common themes throughout the whole of chemistry, so the change of name for the Subcommittee was a deliberate move away from being regarded as a (possibly dying) niche area to something of wide and vital significance. In 2005 the UK Engineering and Physical Sciences Research Council (EPSRC) held a workshop to bring together the academic and industrial chemistry community to discuss the way forward for physical organic chemistry, which was defined as “studies of the dynamics, reactions and interactions of organic molecules and systems leading to quantitative understanding of the interplay between structure, function and reactivity.” This led to a focused funding initiative in the years that
