Asymmetric synthesis of (-)-helicene, as well as preparation of its lower homologues, completes the series of carbon-sulfur -, -, -, and helicenes. Spectroscopic and electrochemical studies of this series provide an absorption onset-based band gap, E g = 3.40 eV, for a cross-conjugated (C 2S) n helix; this value may be compared to E g = 3.59 eV obtained from TD-DFT computed excitation energies for a series of dimethyl-substituted [n]helicenes (n ≥ 31).
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry