Chemistry & Biochemistry

CHM 598 Photochemistry Spring 2005

Ian R. Gould PS D-109 965-7278 igould@asu.edu

Announcements

Syllabus

Homework

Lecture Sources

Reference Materials/Textbooks

The sources that I used to generate each lecture will be recorded here

Lectures 26 and 27, April 26th and 27th Photography. A very simple review of photograohy can be found in Chemtech, Vol 9 (1979), p 25-35, by John Thirtle (no direct link). A comprehensive review of electron transfer in photography can be found in J. R. Fyson, P. J. Twist and I. R. Gould "Electron Transfer Processes in Solver Halide Photography", In: Electron Transfer in Chemistry, Volume 5, V. Balzani (Ed), Wiley, 2001 (New York), page 285. Two-electron sensitization is described in Gould, I. R.; Lenhard, J. R.; Muenter, A. A.; Godleski, S. A.; Farid, S. J. Am. Chem. Soc. 2000, 122, 11934.

Lecture 25, April 21st Photopolymers, Photoinitiation, Onium Salt Photochemistry. This lecture was mainly from the very nice introduction to photopolymers and resists by Arnost Reiser, Photoreactive Polymers. The Science and Technology of Resists, Wiley-Interscience, 1989. Some of the onium salt photochemistry discussed is not yet published.

Lecture 24, April 19th Singlet Oxygen Reactions. The Ene Reaction as a Paradigm Difficult Problem. Again, most of the basic stuff in this lecture came from my own Ph.D. thesis. A good review of singlet oxygen reactions is by A. A. Gorman (my Ph.D. advisor) in Advances in Photochemistry, 1992, 17, 217. The product analysis work on the ene reaction is summarized by M. Orfanopoulos in Molecular and Supramolecular Photochemistry, Volume 8, page 243. Most of the isotope effect and stereochemical work is described there. The kinetics of the reactions indicating the presence of the exciplex intermediate by reversed temperature dependencies is in Gorman et al, J. Am. Chem. Soc. 1988, 110, 8053.

Lecture 23, April 14th Singlet Oxygen, Electronic Structure and Generation To be honest, most of this lecture came from my own Ph.D. thesis! This subject isn't covered particularly well in the textbooks. The classic reference work is Singlet Oxygen, Edited by H. Wasserman and R. W. Murray, Academic Press, 1972. A good review is by Gorman and Rodgers, Chem. Soc. Rev., 1981, 10, 205.

Lecture 22, April 12th Reactions of Radical Ions (contd) Most of the lecture was taken from the review by S. Mattes and S. Farid in Organic Photochemistry 1983, Volume 6 page 233, Marcel Dekker, Edited by A. Padwa, and Gould and Farid in Acc. Chem. Res.. Cosensitization is also discussed in the Accounts article.

Lecture 21, April 7th Exciplexes in Photochemical Reactions The classic papers that describe the first links between exciplexes and chemical reactions are Farid, Hartmann, Doty, Williams J. Am. Chem. Soc. 1975, 97, 3697 and Caldwell and Smith J. Am. Chem. Soc. 1974, 96, 2994. A good review of exciplex photochemistry is by Mattes and Farid Acc. Chem. Res. 1982, 15, 80. The work on photochemical reactions of phenyl acetylene, that made the link to reactions of geminate radical-ion pairs is described in Mattes, Farid, J. Chem. Soc., Chem. Commun. 1980, 126 (no electronic link).

Lecture 20, April 5th Other Mechanisms of 2+2 Dimerization, Introduction to Exciplexes Again, a reasonable place to look for triplet dimerizations and enone cycloadditions is both "Turro" and "Gilbert and Baggott". I don't know of a good general description of exciplexes in the context that we discussed in class, i.e. the factors that really control the extent of charge transfer. The best determination of the extent of charge transfer that has yet been described is probably ours, Gould, Young, Mueller, Albrecht, Farid J. Am. Chem. Soc. 1994, 116, 3147.

Lectures (part) 18 and 19, March 29th and 31st Alkene/Diene Photochemistry, Isomerization and 2+2 Cycloadditions (Pericyclic Reactions) Again, done well in "Turro" and "Gilbert and Baggott", again, especially in combination! Take a look at Saltiel, Ganapathy and Werking J. Phys. Chem. 1987 91, 2755 for a picture of the S1 and T1 surfaces for stilbene isomerization. See Bernardi, Olivucci and Robb J. Photochem. Photobiol. A 1997, 105, 365 for the nice pictures of the computed energy surfaces for the 2+2 photodimerization of excited ethylene. Click HERE for my picture of the dimerization surface linking the mechanism that we drew in class to the surface.

Lectures 16, 17 and part 18, March 22nd, 24th and 29th Ketone Photochemistry and Intersystem Crossing in radical Pairs and Biradicals Done well in "Turro" and "Gilbert and Baggott", especially in combination! More details on dibenzylketone (DBK) photochemistry can be found in Turro and Kraeutler Acc. Chem. Res. 1980, 13, 369 and more details on triplet radical pair and triplet biradical dynamics and discussions of intersystem crossing mechanisms in Gould, Turro and Zimmt, Adv. Phys. Org. Chem., 1984, 20, p 1 (no electronic link), and Doubleday, Turro and Wang Acc. Chem. Res., 1989, 22, 199. The classic paper on intersystem crossing in biradicals is Salem, Angew. Chem. Int. Ed. 1972, 11, 92 (we don't have an electronic link).

Lectures 14 and 15, March 8th and 10th Steady-state and time-resolved photochemical kinetics Both "Turro" and "Gilbert and Baggott" do a reasonable job on these subjects, particularly Gilbert and Baggott for time-resolved kinetics. My favorite kinetics book, however, is Kinetics and Mechanism, by John Moore and Ralph Pearson.

Lecture 13, March 3rd Electron Transfer with Emphasis on Bimolecular Reactions The lecture started with the discussion of the work by Closs et al on the distance dependence of electron transfer and the connection between electron, hole and energy transfer. The latter paper must surely become a "classic". The work on bimolecular electron transfer reactions came mainly from our papers in Acc. Chem. Res. and Chem. Phys.. The Acc. Chem. Res. paper deals more with the general dynamics of Contact and Solvent-Separated Radical-Ion Pairs, and the Chem. Phys. paper deals more with the connection between radiative charge-transfer and electron transfer kinetics.

Lectures 11, 12, February 24th, March 1st Electron Transfer The Gilbert and Baggott book gives a reasonable introduction to electron transfer. The rest of the lecture on electron transfer theory doesn't really come from any one source, it sort of came out of my head. You won't find electron transfer theory described exactly the way that we talked about it in class in any one paper. For some classic review articles on electron transfer theory, look HERE. The classic paper on bimolecular electron transfer reactions by Rehm and Weller is in the Israel Journal of Chemistry, 1970, Volume 8, page 259 (it was a special issue that published the papers from a symposium). We do not have an electronic link to this paper. The other classic paper that we talked about by Closs and Miller, the one that prompted Rudy Marcus to send Gerhard Closs a Valentine's Day card(!), was in J. Am. Chem. Soc., 1984, Volume 106, page 3047.

Lecture 10, February 22nd Energy Transfer contd, and start of Electron Transfer (lecture abbreviated by fire alarm) The two papers that we discussed in class were the classic Backstrom and Sandros, Acta Chem Scand, 1958, 12, p. 823 (we do not have an electronic link to this journal), and that by Sigman and Closs. Turro has nice pictures of the relation between orbitals energies on energy transfer on pages 306, 307.

Lecture 9, February 17th: Energy Transfer This lecture was mainly taken from Turro and Gilbert and Baggott. The Wigner spin rules are discussed in Gilbert and Baggott on page 176, and diffusion kinetics are discussed in Gilbert and Baggott on pages 179-181. The Classic paper on singlet-singlet energy transfer as a molecular ruler is by Stryer and Haughland, PNAS, 1967, 58, p 719. For an overview on this subject, see Selvin, Nature Structural Biology, 2000, 7, p 730.

Lecture 8, February 15th: Radiationless Transitions contd. and Intersystem Crossing The charge-transfer radiationless transition material was mainly from Caspar and Meyer, J. Phys. Chem., 1983, 87, 952, and Gould and Farid, Acc. Chem. Res., 1996, 29, 522. The best general discussion of intersystem crossing is by Turro. The example of hyperfine induced ISC came from Kuciauskas, Liddell, Moore, Moore and Gust, J. Am. Chem. Soc., 1988, 120, 10880, see also Gust, Moore and Moore, Acc. Chem. Res., 2001, 34, 40. For a recent discussion of the mechanisms of ISC in CT states that I didn't have time to discuss in class, see Gould, Boiani, Gaillard, Goodman and Farid, J. Phys. Chem A, 2003, 107, 3515.

Lecture 7, February 10th: Radiationless Transitions This lecture was partly from "Turro" and "Gilbert and Baggott", but mainly from Gould, Noukakis, Gomez-Jahn, Young, Goodman and Farid, Chem. Phys. 1993, 176, 439.

Lecture 6, February 8th: Absorption Spectra, understanding intensities. This lecture was mainly taken from "Turro" and "Gilbert and Baggott". For a nice picture showing intensity borrowing from work that we did a few years ago (Gould, Young and Farid, J. Phys. Chem. 1991, 95, 2668) click HERE. Shown is the absorption spectrum of tetracyanoanthracene and also the tetracyanoanthracene/pentamethylbenzene charge-transfer (CT) complex. The CT absorption is forbidden at zero order (for orbital overlap reasons), but "borrows" (steals) intensity dramatically from the allowed LE absorption of the TCA. In the complex, the intense structured absorption of the tetracyanoanthracene is very "stolen". The reference for the classic Strickler Berg article is S. J. Strickler and R. A. Berg, J. Chem. Phys. 1962, 37, 814.

Lectures 4 and 5, February 1st and 3rd: Orbital and State Correlation Diagrams, Reaction Energy Surfaces, Funnels, Cones, Conical Intersections etc This lecture was mainly taken from "Turro", "Michl and Bonacic-Koutecky" and "Gilbert and Baggott". For some nice pictures of funnels, cones and conical intersections, click HERE (you will have to click on the picture links to see them), and HERE, specifically Figure 6.4. For a really pretty picture of a conical intersection of excited and ground state surfaces from work in my own lab, click HERE.

Lecture 3, January 25th: MO and VB descriptions of paradigm sigma and pi-bond cleavage reactions This lecture was mainly taken from "Michl and Bonacic-Koutecky" and "Shaik, Schlegel and Wolfe".

Lecture 2, January 20th: Orbital and state diagrams of real molecules, energy calibrations This lecture was mainly taken from "Turro". Many other books deal with this subject, but Turro is the clearest. The energy calibration part is quite trivial, this stuff is in many textbooks, or in no textbooks because it is so basic. For energies of excited states you can look in "The Handbook of Photochemistry".

Lecture 1, January 18th: Introduction to descriptions of electronic states and quantum theory underlying singlet and triplet states. From a variety of sources, including "Turro", "Michl and Bonacic-Koutecky", "Klessinger and Michl", "Gilbert and Baggott", and another book not on the textbook page, "Theoretical aspects of physical organic chemistry : the SN2 mechanism" by S. Shaik, H. B. Schlegel and S. Wolfe. However, you will not find the material that we covered today organized in exactly the way that it was presented in any of these textbooks.

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