Premium
Supramolecular Triad and Pentad Composed of Zinc–Porphyrin(s), Oxoporphyrinogen, and Fullerene(s): Design and Electron‐Transfer Studies
Author(s) -
Schumacher Amy Lea,
Sandanayaka Atula S. D.,
Hill Jonathan P.,
Ariga Katsuhiko,
Karr Paul A.,
Araki Yasuyuki,
Ito Osamu,
D'Souza Francis
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200601854
Subject(s) - triad (sociology) , porphyrin , supramolecular chemistry , fullerene , photochemistry , chemistry , electron transfer , photoinduced electron transfer , ultrafast laser spectroscopy , electron acceptor , acceptor , electron donor , molecule , organic chemistry , catalysis , spectroscopy , psychology , physics , quantum mechanics , psychoanalysis , condensed matter physics
Abstract By adopting a “covalent–coordinate” bonding approach, novel supramolecular pentad and triad molecules composed of zinc–porphyrin(s), fullerene(s), and oxoporphyrinogen redox‐/photoactive entities have been constructed, and also characterized by means of spectral and electrochemical techniques. The geometry and electronic structures of the pentad and the triad were deduced by means of DFT calculations. Free‐energy calculations suggested that the photoinduced electron/energy transfer from the zinc–porphyrin (ZnP) singlet‐excited state to the imidazole modified fullerene (ImC 60 ) acceptor and oxoporphyrinogen (OxP) entities is feasible for both the triad and the pentad. The charge‐separation rates ( k CS ) determined from picosecond time‐resolved emission studies were higher for pentad (C 60 Im:ZnP) 2 –OxP than for the corresponding triad, C 60 Im:ZnP–OxP. A comparison of the k CS values previously reported for the covalently linked bis(zinc–porphyrin)–oxoporphyrinogen triad suggests that employing a fullerene acceptor improves the electron‐transfer rates. Nanosecond transient absorption studies provide evidence for the occurrence of electron‐transfer processes. Lifetimes of the radical ion pairs ( τ RIP ) are in the range of hundreds of nanoseconds, which indicates that there is charge stabilization in the supramolecular systems.