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Combining Zinc Phthalocyanines, Oligo( p ‐Phenylenevinylenes), and Fullerenes to Impact Reorganization Energies and Attenuation Factors
Author(s) -
Krug Marcel,
Stangel Christina,
Zieleniewska Anna,
Clark Timothy,
Torres Tomás,
Coutsolelos Athanassios G.,
Guldi Dirk M.
Publication year - 2019
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201900780
Subject(s) - excited state , photoexcitation , ultrafast laser spectroscopy , chemistry , electron donor , ground state , electron acceptor , fullerene , electron transfer , acceptor , triplet state , photoinduced electron transfer , photochemistry , nanosecond , quenching (fluorescence) , fluorescence , spectroscopy , atomic physics , organic chemistry , laser , physics , quantum mechanics , optics , condensed matter physics , catalysis
A study on electron transfer in three electron donor‐acceptor complexes is reported. These architectures consist of a zinc phthalocyanine (ZnPc) as the excited‐state electron donor and a fullerene (C 60 ) as the ground‐state electron acceptor. These complexes are brought together by axial coordination at ZnPc. The key variable in our design is the length of the molecular spacer, namely, oligo‐ p ‐phenylenevinylenes. The lack of appreciable ground‐state interactions is in accordance with strong excited‐state interactions, as inferred from the quenching of ZnPc centered fluorescence and the presence of a short‐lived fluorescence component. Full‐fledged femtosecond and nanosecond transient absorption spectroscopy assays corroborated that the ZnPc ⋅ + ‐C 60 ⋅ − charge‐separated state formation comes at the expense of excited‐state interactions following ZnPc photoexcitation. At a first glance, the ZnPc ⋅ + ‐C 60 ⋅ − charge‐separated state lifetime increased from 0.4 to 86.6 ns as the electron donor‐acceptor separation increased from 8.8 to 29.1 Å. A closer look at the kinetics revealed that the changes in charge‐separated state lifetime are tied to a decrease in the electronic coupling element from 132 to 1.2 cm −1 , an increase in the reorganization energy of charge transfer from 0.43 to 0.63 eV, and a large attenuation factor of 0.27 Å −1 .