Coupling of Large-Amplitude Side Chain Motions to the Excited-State H-Atom Transfer of Perylene Quinones: Application of Theory and Experiment to Calphostin C

The excited-state intramolecular H-atom transfer reactions of hypocrellins B and A are compared with those of calphostin C. On the basis of the results of transient absorption measurements and ab initio quantum mechanical calculations, it is concluded that large-amplitude conformational changes are coupled to the Hatom transfer in calphostin C, just as they are in hypocrellins A and B. The calculations on this very large molecule with a very complex ground electronic state potential energy surface were made possible by the use of highly scalable electronic structure theory codes on large parallel computers. Disciplines Chemistry Comments Reprinted (adapted) with permission from Journal of Physical Chemistry A 105 (2001): 1057, doi:10.1021/ jp0035941. Copyright 2001 American Chemical Society. This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/chem_pubs/390 Coupling of Large-Amplitude Side Chain Motions to the Excited-State H-Atom Transfer of Perylene Quinones: Application of Theory and Experiment to Calphostin C Anindya Datta, Pradipta Bandyopadhyay, Jin Wen, Jacob W. Petrich,* and Mark S. Gordon* Department of Chemistry, Iowa State UniVersity, Ames, Iowa 50011 ReceiVed: October 2, 2000; In Final Form: NoVember 6, 2000 The excited-state intramolecular H-atom transfer reactions of hypocrellins B and A are compared with those of calphostin C. On the basis of the results of transient absorption measurements and ab initio quantum mechanical calculations, it is concluded that large-amplitude conformational changes are coupled to the H-atom transfer in calphostin C, just as they are in hypocrellins A and B. The calculations on this very large molecule with a very complex ground electronic state potential energy surface were made possible by the use of highly scalable electronic structure theory codes on large parallel computers.