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Dynamic Behavior, Electrochromism, and Two-Photon Absorption of Dicyanomethylenated Quinacridone
- Takeda, Takashi, Sugihara, Hiroyuki, Suzuki, Yasutaka, Kawamata, Jun, Akutagawa, Tomoyuki
- Journal of organic chemistry 2014 v.79 no.20 pp. 9669-9677
- X-radiation, absorption, chemical structure, electrochemistry, nuclear magnetic resonance spectroscopy, organic chemistry
- Molecular structures of dicyanomethylenated quinacridone (1) as a solid and in solution were examined on the basis of single-crystal X-ray structural analysis, temperature-dependent ¹H NMR in CD₂Cl₂, and theoretical calculations. Crystal 1 had a curved, butterfly-shaped molecular structure. Thermally activated flipping between the curved, butterfly-shaped structure and an armchair structure occurred in solution. Electrochemical reduction triggered a dynamic change from the curved, butterfly-shaped conformation in the neutral state to a planar conformation in the dianion state, which represented electrochromic behavior with electrochemical bistability. A large two-photon absorption cross section of compound 1 was observed in the resonance-enhancement region of 423 GM (1 GM = 1 × 10–⁵⁰ cm⁴ s photon–¹ molecule–¹) at 710 nm. Multiple donor–acceptor charge-transfer pathways of molecule 1 enhanced two-photon absorption.