title: Dynamic behavior, electrochromism, and two-photon absorption of dicyanomethylenated quinacridone.
abstract: 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 (1)H 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) cm(4) s photon(-1) molecule(-1)) at 710 nm. Multiple donor-acceptor charge-transfer pathways of molecule 1 enhanced two-photon absorption.
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , Katahira 2-1-1, Sendai, Miyagi 980-8577, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Takeda
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sugihara
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Jun
authors.initials: J
authors.lastname: Kawamata
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Akutagawa
mesh_terms: D018360:Crystallography, X-Ray; D004563:Electrochemistry; D006576:Heterocyclic Compounds, 4 or More Rings / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry*; D017785:Photons; D055585:Physical Phenomena; D011789:Quantum Theory
chemical_list: D006576:Heterocyclic Compounds, 4 or More Rings; D009570:Nitriles; C484590:quinacridone