Donor-substituted octacyano[4]dendralenes: A new class of cyano-rich non-planar organic acceptors

Benjamin Breiten, Yi Lin Wu, Peter D. Jarowski, Jean Paul Gisselbrecht, Corinne Boudon, Markus Griesser, Christine Onitsch, Georg Gescheidt, W. Bernd Schweizer, Nicolle Langer, Christian Lennartze, Francois Diederich*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

Double [2+2] cycloaddition/retro-electrocyclisation reactions between tetracyanoethene (TCNE) and various anilino-capped buta-1,3-diynes furnished a series of octacyano[4]dendralene deri vatives featuring intense, low-energy intramolecular charge-transfer absorptions. These novel chromophores are strong electron acceptors and undergo facile one-electron reductions at potentials (-0.09 to -0.17 Ev vs. Fc+/Fc, in CH2Cl2-0.1 M nBu4NPF6) lower than those reported for the benchmark organic acceptors, such as TCNE (-0.32 eV) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) (-0.25 eV). The electron-accepting power of one octacyano[4]dendralene, as expressed by the computed adiabatic electron affinity (EA), compares to that of the reference acceptor 2,3,5,6-tetrafluoro-7,7,8,8- tetracyanoquinodimethane (F4-TCNQ) used as a p-type dopant in organic light-emitting diodes (OLEDs) and solar cells. Gas-phase density functional theory (DFT) calculations predict a stretchedout conformation as the global energy minimum for octacyano[4]dendralenes. In the solid state however, folded conformations were observed for two structures by X-ray analysis. Taking the solid state environment approximately into account calculations predict a energetical degeneracy between the stretched-out and folded conformation. Therefore conformational preference probably is a result of supramolecular dimer formation, mediated by two pairs of intermolecular, antiparallel dipolar CN/CN interactions.

Original languageEnglish (US)
Pages (from-to)88-93
Number of pages6
JournalChemical Science
Volume2
Issue number1
DOIs
StatePublished - 2011

ASJC Scopus subject areas

  • Chemistry(all)

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