Quadrupolar Cyclopenta[hi]aceanthrylene‐Based Electron Donor‐Acceptor‐Donor Conjugates: Charge Transfer versus Charge Separation. Issue 41 (5th September 2019)

• Record Type: Journal Article
• Authors: Schierl, Christoph; Alex, Wiebke; Mateo, Luis M.; Ballesteros, Beatriz; Shimizu, Daiki; Osuka, Atsuhiro; Torres, Tomas; Guldi, Dirk M.; Bottari, Giovanni
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 41(2019)
• Page Start: 14644
• Page End: 14652
• Publication Date: 2019-09-05
• Subjects: absorption -- charge transfer -- fluorescence -- hydrocarbons -- porphyrinoids; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201906206
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: 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 . Abstract : Cards on the table : Cyclopenta[ hi ]aceanthrylenes (CPAs) functionalized at two of the peripheral positions with trimethylsilylethynyl, as well as with electron‐donating 4‐ethynyl‐ N, N ‐dimethylaniline, ethynyl Zn II phthalocyanine, and ethynyl Zn II porphyrin units have been prepared and investigated by means of photophysical, electrochemical, and spectro‐electrochemical techniques.