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I-APS Awards:  David G. Whitten

Several weeks ago it was announced that David Whitten will receive the 1998 IAPS award in photochemistry at the Winter Conference in January, 1998. Dave (as he is known by most of his friends and acquaintances) is my Ph.D. research mentor and friend; therefore, it is natural that I write a short biography of him in honor of his award.

Dave was born in Washington, DC and raised in the Baltimore, MD area. He attended Johns Hopkins University and received a B.S. in Chemistry in 1959. He remained at Johns Hopkins for his Ph.D. which he completed under the direction of Prof. A. H. Corwin. Dave's Ph.D. research set the stage for one of the areas where his research has had a large impact over the years -- the spectroscopy of porphyrins and metalloporphyrins. While in graduate school Dave found time for some pursuits outside of the laboratory -- he married Jo Wright. After completing his Ph.D. in 1963 Dave and Jo moved to Pasadena, California where Dave first worked as a U.S. Army officer (assigned to NASA) at the Jet Propulsion Laboratory. Some of Dave's work at JPL reflected his continued interest in porphyrin chemistry, but he also worked on projects related to applications of mass spectrometry to planetary science. After his two year stint with the Army at JPL, Dave was an NIH postdoctoral fellow in George Hammond's group at CalTech. At CalTech, among other projects related to organic photochemistry, Dave carried out studies which explored the correlation between the outcome of reactions induced by ionizing radiation and UV photolysis.

Dave began seeking academic positions and received several offers, including one from the University of North Carolina in Chapel Hill. Although he had some "trepidation" about moving into the "deep south", Dave accepted the position in the Fall of 1966 at North Carolina as an Assistant Professor of Organic Chemistry. Dave began his independent academic career by going back to his roots -- he initiated detailed studies of porphyrin photochemistry. During the early years Dave's group focused on examining energy and electron transfer processes ensuing from the singlet and triplet excited states of various metalloporphyrins. This work on porphyrin photochemistry and photophysics formed the core of Dave's first publications from Chapel Hill, and has been a recurring theme in his research throughout his entire career. Dave was also quite interested in the photochemistry of nitrogen aromatics; in particular his group published a number of papers on the photochemistry of the aza stilbene analogs (4-pyridyl)-2-phenylethylene and l,2- bis(4-pyridyl)ethylene. This work was a prelude to his idea to use paraquat as an electron acceptor in excited state electron transfer reactions with transition metal complexes (see below).

About 3 or 4 years after starting at Chapel Hill, Dave joined forces with another young Professor, Thomas Meyer, and the two began collaborative investigations on the mechanism by which various organic and inorganic species quench the luminescent metal-to-ligand charge transfer excited state of Ru(bpy)32+. This collaboration was a natural for the two groups -- Dave had already amassed a significant background in photoinduced electron transfer reactions through his work on the porphyrins and the nitrogen heterocycles, while Tom had a great deal of expertise with electron transfer and spectroscopy of inorganic complexes. Before Whitten and Meyer began working together on the photoinduced electron transfer problem, Gafney and Adamson, among others, had reported that various metal ion quench the luminescence from Ru(bpy)32+; however, there wasn't any definitive evidence that the quenching was due to photoinduced electron transfer. In the first of a series of publications on the topic, Meyer and Whitten used conventional flash photolysis to demonstrate that the one electron reduced form of paraquat is produced as a result of the interaction of photochemically excited Ru(bpy)32+ and ground state paraquat. This paper, which appeared in 1974, was the first to provide unequivocal evidence that the charge transfer excited state of Ru(bpy)32+ engages in photoinduced electron transfer reactions. The 1974 communication was followed shortly by a series of papers demonstrating that Ru(bpy)32+ undergoes photoinduced electron transfer with a variety of organic donors and acceptors. Although other research groups clearly played an important role in the development of Ru(bpy)32+ photochemistry, it is clear that the early work on photoinduced electron transfer done by the Meyer-Whitten collaboration set the stage for the vast amount of research that was subsequently carried out on the application of metal complexes to photoinduced electron transfer and photochemical conversion of solar energy.

Dave Whiten has also made significant contributions to the area of the chemistry of organized assemblies. Dave's interest in this area began during a sabbatical year (supported by a Humboldt Fellowship) in 1975 with Hans Kuhn at the Max-Planck-Institut f�r Biophysikalische Chemie in G�ttingen, Germany. While in Germany, Dave studied the cis-trans photoisomerization of surfactant thioindigo dyes incorporated into multilayer assemblies that were fabricated using the Langmuir-Blodgett technique. Upon returning to Chapel Hill, Dave established a Langmuir-Blodgett monolayer trough in his laboratory and began working actively in the area of exploring photophysics arid photochemistry in monolayer and multilayer assemblies. Some high points of his work on Langmuir-Blodgett monolayer and multilayer assemblies include his studies of the photophysics of a wide variety of surfactant stilbene derivatives in multilayer assemblies. Dave's interest in monolayers and multilayers led him to begin exploring phototophysics and photochemistry in other organized assemblies including micelles, vesicles and microemulsions. In this work Whitten effectively combined his interests in organic photochemistry, porphyrin photochemistry and photoinduced electron transfer to produce a large body of insightful work which provided a great deal of information regarding the structure and properties of organized assemblies.

While all of this research was going on in the laboratory Dave's academic career had been moving forward at a fast pace. He was promoted to Full Professor at UNC in 1973 and then was promoted to M. A. Smith Professor of Chemistry in 1980. In 1983 Dave decided to leave Chapel Hill and move to Rochester, NY where he assumed the C. E. Kenneth Mees Professorship in Chemistry at the University of Rochester. Some impetus for Dave's move to Rochester was the potential for initiating collaborations with industrial scientists interested in the photosciences -- indeed Rochester has been at the forefront of applied photosciences for a over a century in part due to the presence of Kodak, Bausch and Lomb, and Xerox, among other companies. Shortly after moving, Dave and his colleagues at Rochester, in collaboration with groups from Kodak and Xerox were successful in obtaining funding from the National Science Foundation to establish the Center for Photoinduced Charge Transfer. Dave was selected to act as the Director of the Center, and he held this position from 1989 - 1995. During Dave's tenure at Rochester he also served as Chairman of the Chemistry Department from 1988 - 1991 and again from 1995 - 1997.

While at Rochester Dave's research group continued to study photochemistry in organized assemblies as well as the reactivity of organic radical ions that are produced by photoinduced electron transfer. A relatively recent research emphasis emanated from Dave's earlier work on surfactant stilbene derivatives in monolayers and vesicles. Early on Whitten and co-workers noticed that when incorporated into monolayer assemblies, stilbene chromophores exhibit be spectroscopic signature of H-aggregates. This early observation has been elaborated upon in more recent studies of vesicles consisting of phospholipid molecules that contain stilbene, azobenzene and squaraine chromophores. The recent vesicle work indicates that a variety of stilbene-shaped chromophores form a chiral tetramer (a "pinwheel" aggregate) when they are incorporated into a vesicle bilayer. Quite interestingly, the experimental work on the chiral aggregates is strongly supported by computer simulations of stilbene aggregate structure that have been carried out by Jerry Perlstein at the Center for Photoinduced Charge Transfer.

Very recently Dave has embarked on yet another new adventure in science. In August of this year he moved from Rochester to the Los Alamos National Laboratory in New Mexico. While it is yet unclear how the new environment will influence his research, it is likely that Dave will successfully harness the strengths of Los Alamos in the areas of biological and materials chemistry to continue his work in the area of chemistry at interfaces and in organized assemblies.

Dave's scientific, academic and administrative accomplishments have been recognized by many awards which include an A. P. Sloan Fellowship, the Humboldt Fellowship, the Japan Society for Promotion of Science Fellowship, the ACS Award in Colloid and Surface Chemistry, and two NSF Awards for Special Creativity. He recently accepted the position as Editor-in-Chief of the ACS publication Langmuir, and he will manage the journal from his new office at Los Alamos.

While it is clear that Dave Whitten is a most accomplished scientist and academician, people who know him recognize that his most admirable trait is his personality. Dave is a very outgoing person -- he possesses a keen sense of wit, and he has a broad range of interests that include history, art, music, pop culture and the climate. Furthermore, those who share any amount of time with Dave know very well that there is only one thing more important to him than his science -- and that is the sport of running. Dave is a very accomplished runner, literally having logged tens of thousands of miles running in every country and terrain imaginable. He typically runs 50 - 70 miles per week and competes in 3 - 4 marathons per year, and when he competes, he usually finishes among the top in his age group. Indeed, several years ago he was ranked 3rd in the nation among marathon runners in his age group.

It is quite clear that Dave Whitten is a leader in every respect. It is most fitting for him to receive the IAPS award in photochemistry and I take this opportunity to congratulate him on his past accomplishments and wish him of luck with his future endeavors.

Kirk Schanze
Department of Chemistry
University of Florida
November, 1997



 

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