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| Kinetic isotope effect | |
|---|---|
| Name | Kinetic isotope effect |
| Field | Physical chemistry |
| Introduced | Early 20th century |
| Notable | Harold Urey; Melvin Calvin; Robert Sanderson Mulliken |
Kinetic isotope effect The kinetic isotope effect is the change in reaction rate that occurs when an atom in a reactant is replaced by one of its isotopes, a phenomenon first observed in early studies linked to Harold Urey and expanded through work associated with Melvin Calvin and Robert Sanderson Mulliken. It provides mechanistic insight used across investigations associated with Linus Pauling, Ahmed Zewail, Otto Hahn, C. A. Coulson and experimental programs at institutions including Massachusetts Institute of Technology, University of California, Berkeley, Cambridge University, Max Planck Society and Harvard University. The effect underpins analytic methods employed in laboratories at Lawrence Berkeley National Laboratory, Oak Ridge National Laboratory, Argonne National Laboratory and industrial research at DuPont, Dow Chemical Company and BASF.
The kinetic isotope effect arises because isotopic substitution alters vibrational frequencies and zero-point energies of chemical bonds, an idea developed in theoretical contexts by researchers at Princeton University, University of Chicago, University of Oxford, Columbia University and California Institute of Technology. Historical experimental milestones include isotope exchange studies reported by investigators affiliated with Royal Society, National Academy of Sciences (United States), Deutsche Forschungsgemeinschaft and early mass spectrometry performed at National Physical Laboratory (United Kingdom). The effect is measured and interpreted in research programs connected to Nobel laureates such as Frederick Sanger, Dorothy Hodgkin, Richard Feynman and Erwin Schrödinger.
Quantum mechanical explanations of the kinetic isotope effect deploy transition state theory and tunneling models refined by theoreticians at University of Göttingen, University of Cambridge, ETH Zurich, University of Tokyo and Imperial College London. Seminal theoretical contributions came from groups around Max Planck, Albert Einstein, Niels Bohr, Linus Pauling and Robert Oppenheimer, and later computational formalism advanced by researchers at Bell Labs, IBM Research, Microsoft Research and Los Alamos National Laboratory. Mechanistic categories—primary effects, secondary effects, and tunneling contributions—were elaborated in contexts related to publications from Nature, Science (journal), Journal of the American Chemical Society, Proceedings of the National Academy of Sciences and Angewandte Chemie.
Measurements of kinetic isotope effects use spectrometry and tracer techniques developed at Massachusetts General Hospital, Johns Hopkins University, Mayo Clinic, Scripps Research Institute and facilities like CERN for precision isotope separation. Methods include infrared spectroscopy refined at Bell Labs, nuclear magnetic resonance techniques from Bruker Corporation and mass spectrometric approaches pioneered at Finnigan, Thermo Fisher Scientific and Agilent Technologies. Kinetic experiments are often run in laboratories supporting projects by National Institutes of Health, Wellcome Trust, European Research Council and regulatory frameworks influenced by United States Food and Drug Administration and European Medicines Agency.
Primary kinetic isotope effects and secondary kinetic isotope effects are categorized and studied in frameworks associated with IUPAC, Royal Society of Chemistry, American Chemical Society, Deutscher Chemiker Verband and specialist conferences held at Gordon Research Conferences, Faraday Discussions and International Union of Pure and Applied Chemistry symposia. Heavy-atom isotope effects (e.g., 13C, 18O, 15N) feature in research programs from Stanford University, Yale University, University of Michigan, University of Toronto and McGill University, while hydrogen/deuterium/tritium effects inform studies at Brookhaven National Laboratory, Pacific Northwest National Laboratory, Rutherford Appleton Laboratory and Korea Advanced Institute of Science and Technology.
Kinetic isotope effects are applied to elucidate enzyme mechanisms investigated by groups linked to Max Perutz, John Kendrew, Kurt Wüthrich, Thomas Cech and Jennifer Doudna, and to probe reaction pathways in synthetic chemistry programs at Bayer, Pfizer, GlaxoSmithKline, Merck & Co. and Eli Lilly and Company. Environmental and geochemical applications connect to work by Alfred Wegener, Marie Tharp, Milutin Milanković, Claude Lorius and institutions such as United States Geological Survey, NOAA and NASA. Isotope effects also support forensic and provenance investigations at museums and archives including British Museum, Smithsonian Institution, Louvre, Metropolitan Museum of Art and scholarly projects at Bibliothèque nationale de France.
Computational modelling of kinetic isotope effects utilizes quantum chemistry packages developed by teams at Gaussian, Inc., Schrödinger, LLC, Psi4 Project, NWChem and algorithms arising from research at Los Alamos National Laboratory, Sandia National Laboratories, Argonne National Laboratory and Brookhaven National Laboratory. Methods integrate density functional theory from groups at John von Neumann Center-era institutions, path integral approaches related to work by Richard Feynman, and molecular dynamics simulations advanced at Princeton Plasma Physics Laboratory, Oak Ridge Leadership Computing Facility and Argonne Leadership Computing Facility. Validation studies are reported in journals associated with Royal Society, American Chemical Society, Nature Publishing Group and conferences hosted by American Physical Society and European Physical Society.