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47401-SE
60 Years of Physical Organic Chemistry, at the ACS National Meeting, August 2007, Boston, MA

Steven Fleming, Brigham Young University

The symposium “60 Years of Physical Organic Chemistry” was held at the 2007 Fall ACS Meeting in Boston on August 22. There were 12 speakers and attendance varied from 50 to 120 through the daylong event. There was also a banquet held the evening of August 21 associated with the event. The speakers and the titles of their presentations are listed below. The symposium was organized by David Crumrine, Steve Fleming, and Laren Tolbert.

The following two speakers were supported by this PRF-SE grant:

Hiizu Iwamura, Tokyo University

Title: Synthetic and supramolecular approaches to carbene-based magnets.

Professor Iwamura's abstract: Since the photochemical production of bis(2,4,6-trichlorophenyl)carbene as a persistent triplet species by Zimmerman, H. E. in 1964, diarylcarbenes have attracted a lot of scientific interest as the building blocks for organic molecules having very high-spin ground states. The work was highlighted by the construction of the nonacarbene with a nonadecet (S = 9) ground state and therefore strong paramagnetic properties. Having established that supramolecular approaches using high spin organic ligands with magnetic metal ions are effective in constructing extended and ordered spin systems, we pursued a potential of developing photoresponsive magnetic materials. Photolysis of dilute-paramagnetic metal complexes carrying di(4-pyridyl)diazomethane and its higher analogs as ligands gave the corresponding polycarbenes in which the spins at carbene centers and magnetic metal ions aligned as designed to form variously paramagnetic networks, spin glasses, and single-molecule magnets. Some of the carbene centers survived at 230 K in the parent crystals.

Masahiro Irie, Rikkyo University

Title: Photoresponsive diarylethene single crystals

Professor Irie's abstract: Some diarylethene derivatives undergo photochromism even in the single crystalline phase. The single crystalline photochromism was proved by dichroism as well as in situ X-ray crystallographic analysis. The X-ray crystallographic analysis revealed that the end to end distance of the long molecular axis and the thickness of the molecules shrink upon irradiation with UV light and expand upon visible irradiation. The geometrical structural change in crystals induced the reversible change of the surface morphology of the single crystals (1,2). Furthermore, the molecular crystals based on diarylethene chromophores and with size ranging from 10 to 100 micrometers exibit rapid and reversible macroscopic changes in shape and size induced by UV and visible light.

M. Irie et al., Science 291, 1769 (2001) 2. M. Morimoto, M. Irie, Chem. Commun. 3895 (2005)

The symposium recognized the lifetime achievements of:

Howard Zimmerman, University of Wisconsin

Professor Zimmeran's abstract: This lecture contains the beginning and the current research in what we term the “Z-Group”. The beginnings serve two purposes: (a) A historical one, and (b) Providing background for the Current Research portion. The lecture deals with (i) stereochemistry, (ii) photochemistry, (iii) solid-state chemistry, (iv) theoretical organic chemistry. The beginnings include: (1) the discovery of kinetic protonation stereochemistry, (2) the original report of how photochemistry could be related to excited state structures, (3) the first organic correlation diagram controlling reactivity. The recent research: (1) deals with the controversy in zwitterionic rearrangements, (2) solid-state reactivity, (3) new heterocyclic photochemistry and conical intersections involved, (4) the structure and reactivity of allenic enolates.

Also participating in the symposium were:

Laren Tolbert, Georgia Institute of Technology

Title: Charge distribution in the ground and excited states of resonance stabilized anions.

Marye Anne Fox, University of California, San Diego

Title: Photochemistry at the nanoscale: Recent advances in photochemistry at nanostructured surfaces.

Albert Padwa, Emory University

Title: From photochemistry to alkaloids

Andrei Kutateladze, University of Denver

Title: Detection and photoamplification of molecular recognition events

David Schuster, New York University

Title: Forty-seven years in organic photochemistry

Richard Givens, University of Kansas

Title: Photoremovable protecting groups: Variations on the photo-Favorskii rearrangement – a mechanistic study

Josef Michl, University of Colorado

Title: Covalently linked dimers of 1,3-diphenylisobenzofuran: Evidence for singlet fission

James Pincock, Dalhousie University

Title: Effect of methoxy substituents on the photoreactivity of arylmethyl substrates

Fred Lewis, Northwestern University

Title: Photoinduced DNA electron transfer revisited

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