Open AccessTime‐resolved energy‐dispersive XAS studies of photoinduced electron transfer intermediates in electron donor–acceptor complexes
Author(s) -
Chen L. X.,
Lee P. L.,
Gosztola D. J.,
Svec W. A.,
Wasielewski M. R.
Publication year - 1999
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049598014861
Subject(s) - electron , x ray absorption spectroscopy , electron transfer , electron acceptor , acceptor , photochemistry , energy transfer , chemistry , materials science , atomic physics , chemical physics , absorption spectroscopy , physics , optics , condensed matter physics , nuclear physics
The structure around the Fe atom of a photoinduced electron transfer intermediate in a di-porphyrin electron donor/acceptor complex is studied with time-resolved energy dispersive X-ray absorption spectroscopy. Photoinduced electron transfer from the lowest excited triplet state ofa Zn porphyrin attached at a fixed 25 D distance by means of a long spacer molecule to an Fe(III) porphyrin occurs with a 6 ms time constant at 77 K. Time domain X-ray absorption measurements show that Fe(III) is transiently photoreduced to Fe(II) and that the bond between the Fe atom and a pyridine molecule ligated to it weakens substantially upon reduction of the Fe. Coupling of ligand loss to reduction of Fe(III) to Fe(II) provides a mean of stabilizing the reduced intermediate.