Department of Chemistry

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John E. Adams

Research Emphasis

Physical Chemistry; Solvation Phenomena; Supercritical Fluids

Education

  • BS, University of Missouri-Rolla, 1974
  • PhD, University of California, Berkeley, 1979

Professional Experience

  • Associate Professor, University of Missouri-Columbia, 1987-present
  • Assistant Professor, University of Missouri-Columbia, 1981-1987
  • Postdoctoral Fellow, Los Alamos National Laboratory, 1979-1981

Honors and Awards

  • AMOCO Foundation Undergraduate Teaching Award, 1987
  • William T. Kemper Fellow for Excellence in Teaching, 1993
  • Excellence in Education Award, MU Division of Student Affairs, 1999

Professional Activities (partial listing of current activities)

  • American Chemical Society:
    • Councilor (University of Missouri Local Section), 1993-present;
    • General Chair, 38th Midwest Regional Meeting, 2003;
    • Committee on Membership Affairs: Associate, 1994 and 2001;
    • Member, 1995-2000; Secretary, 1995 and 2001
  • Alpha Chi Sigma, Professional Chemistry Fraternity Grand Professional Alchemist (national 1st Vice President, 2000-2002; 2nd Vice President, 1998-2000)
  • Alpha Chi Sigma Educational Foundation
    • Vice President, 2000-2002;
    • Assistant Secretary, 1998-2000;
    • Foundation Member, 1999-2009)
    • Chapter Advisor, Delta Chapter (1990-present)

  Research

One of the most fundamental properties of a particular chemical compound is its solubility in various solvents. Although it is generally known that characteristic solubility behavior ultimately derives from the details of the forces acting between the solute and the solvent, between the solute and other solute species, and between the individual solvent molecules, the actual specification of these forces is a difficult problem. Thus, the characterization of the local solvation environment for a specific system still represents a very active research field, one in which there is much to be gained from the joint efforts of theorists and experimentalists.

It is only in recent years that experimentalists have been able to address the problem of what might be called "differential" solvation by probing the structure and dynamics of small solvent molecule clusters of increasing size that contain a single solute species. Since such systems are also amenable to study through theoretical simulations, theorists have contributed greatly to the interpretation of the often ambiguous experimental data. Over the last few years, we have examined small benzene-Arn clusters (n = 2-100) using a variety of Monte Carlo and molecular dynamics techniques and have demonstrated conclusively that the perplexing reported changes in the ultraviolet absorption spectrum of the benzene molecules in these clusters derive from differences in cluster structures. In particular, we have shown that the observed spectra of clusters containing 60 to 100 Ar atoms are a consequence of structures in which the benzene molecule is bound to the surface of a neat Ar cluster (i.e., the benzene molecule is not solvated). Our ongoing efforts in this area include the modeling of molecular solvents, which have more complicated effects on the spectrum of the solute.

research image

Not all of the "supersolvents" used in industry today are compounds that traditionally even have been thought of as solvents. Certainly one of the most versatile materials turns out to be supercritical CO2, the solvent of choice for decaffeinating coffee or for extracting fatty tissue from a protein matrix. Even water, when under supercritical conditions of temperature and pressure, behaves far differently than it does under ordinary conditions, actually becoming an excellent solvent for hydrophobic species and one in which concurrent oxidation of organics can be accomplished. We are adapting many of the same simulation techniques that we have been using in the study of small clusters to the computationally demanding problem of modeling supercritical fluid solutions. Our goal is to determine just how much structural information about the solution can be extracted from the spectroscopy of a dissolved chromophore. (Local increases in the density of the supercritical solvent in the immediate vicinity of solute molecules has been suggested as an explanation for the observed solvation phenomena.) An example of the local environment experienced by a benzene molecule dissolved in supercritical Ar is shown here. (If you have access to RasMol and the Chemscape Chime plug-in, clicking on this graphic will download the atomic coordinates automatically to that application.) Eventually, we want to extend these investigations to mixed solvent systems, in which changes in the solution composition have been observed to produce dramatic changes in solvation ability.

  Recent Representative Publications

  1. A. Siavosh-Haghighi and J. E. Adams
    Rotational relaxation in a nondipolar supercritical fluid: Toluene in CO2.
    J. Phys. Chem. (in press).
  2. J. E. Adams
    Solvatochromism in a near-critical solution: A direct correlation with local solution structure.
    J. Phys. Chem. B 1998, 102, 7544.
  3. J. E. Adams
    Size-dependence of the electronic spectra of benzene-(N2)n clusters.
    J. Chem. Phys. 1998, 109, 6296.
  4. J. E. Adams
    J. Chem. Phys. 92, 1849 (1990).
  5. J. E. Adams and R. M. Stratt
    J. Chem. Phys. 1990, 93, 1332; 1990, 1632.
  6. J. E. Adams and R. M. Stratt
    J. Chem. Phys. 1990, 93, 1358.
  7. R. M. Stratt and J. E. Adams
    J. Chem. Phys. 1993, 99, 775.
  8. J. E. Adams and R. M. Stratt
    J. Chem. Phys. 1993, 99, 789.
  9. J. E. Adams and R. M. Stratt
    J. Chem. Phys. 1996, 105, 1743.
John Adams

Professor and
Associate Chair for Undergraduate Studies

123A and 125A, Chemistry
Tel: 573-882-3245 and 884-2597
email: AdamsJE@missouri.edu

Research

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