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Photoinduced Electron Transfer in Branched Bis(ferrocenylacetylene)‐C 60 Systems: Influence of the Nature of Conjugation
Author(s) -
Pérez Laura,
Shafiqul Islam D.M.,
Araki Yasuyuki,
de la Cruz Pilar,
Cardinali François,
Ito Osamu,
Langa Fernando
Publication year - 2008
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200800335
Subject(s) - chemistry , phenylacetylene , photochemistry , cyclic voltammetry , moiety , homo/lumo , singlet state , excited state , stereochemistry , electrochemistry , organic chemistry , molecule , physics , electrode , nuclear physics , catalysis
Abstract Four new branched 3,4‐ and 3,5‐bis(ferrocenylacetylene)phenyl‐C 60 molcules, in which the bis‐ferrocene donor moieties and C 60 acceptor moiety are covalently linked with phenylacetylene linkage through pyrrolidino and pyrazolino rings on the C 60 moiety, as abbreviated to be (Fc) 2 ≡Ph‐NMPC 60 ( o ‐ and m ‐) and (Fc) 2 ≡Ph‐PzC 60 ( o ‐ and m ‐), respectively, have been prepared in multistep procedures using microwave irradiation, as source of energy. The HOMO–LUMO gaps smaller than 1.25 eV were experimentally determined by cyclic voltammetry (CV) and Osteryoung square‐wave voltammetry (OSWV) for (Fc) 2 ≡Ph‐PzC 60 and (Fc) 2 ≡Ph‐NMPC 60 . In both polar and non‐polar solvents, a photoinduced charge‐separation (CS) process efficiently takes place in (Fc) 2 ≡Ph‐NMPC 60 and (Fc) 2 ≡Ph‐PzC 60 from the singlet excited state of C 60 ( 1 C 60 *), as confirmed by picosecond‐time‐resolved emission spectroscopy. The CS states were confirmed by nanosecond‐transient absorption spectroscopy. The lifetimes of the CS states were evaluated to be ca. 10 ns, which are shorter than those of the similar dyads with phenylenevinylene linkage, suggesting higher electron‐hole conductivity through the phenylacetylene linkage.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)