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Quadrupolar Cyclopenta[ hi ]aceanthrylene‐Based Electron Donor‐Acceptor‐Donor Conjugates: Charge Transfer versus Charge Separation
Author(s) -
Schierl Christoph,
Alex Wiebke,
Mateo Luis M.,
Ballesteros Beatriz,
Shimizu Daiki,
Osuka Atsuhiro,
Torres Tomas,
Guldi Dirk M.,
Bottari Giovanni
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201906206
Subject(s) - excited state , delocalized electron , chemistry , solvatochromism , photochemistry , ultrafast laser spectroscopy , electron donor , acceptor , ground state , singlet state , electron acceptor , porphyrin , spectroscopy , atomic physics , solvent , biochemistry , physics , organic chemistry , quantum mechanics , condensed matter physics , catalysis
Cyclopenta[ hi ]aceanthrylenes (CPAs) have been functionalized at two of the peripheral positions with electronically inert trimethylsilylethynyl ( 1 ), as well as with electron‐donating 4‐ethynyl‐ N , N ‐dimethylaniline ( 2 ), ethynyl Zn II phthalocyanine ( 3 ), and ethynyl Zn II porphyrin ( 4 ) units. Consistent with X‐ray crystal structures of 2 and 4 , analyses of absorption and fluorescence of 2 – 4 point to strong electronic communication between the CPA and the peripheral units, affording quadrupolar electron donor‐acceptor‐donor charge‐transfer conjugates. By virtue of their quadrupolar/dipolar charge‐transfer characters in the excited state, 2 – 4 exhibit fluoro‐solvatochromism. Transient absorption spectroscopy confirmed delocalized quadrupolar ground states and formation of weakly solvent stabilized quadrupolar singlet excited states. The latter transform into strongly stabilized dipolar excited states before deactivating to the ground state in 2 and give rise to a fully charge separated state in 3 and 4 .