title: Lateral extension of π conjugation along the bay regions of bisanthene through a Diels-Alder cycloaddition reaction.
abstract: Diels-Alder cycloaddition reactions at the bay regions of bisanthene (1) with dienophiles such as 1,4-naphthoquinone have been investigated. The products were submitted to nucleophilic addition followed by reductive aromatization reactions to afford the laterally extended bisanthene derivatives 2 and 3. Attempted synthesis of a larger expanded bisanthene 4 revealed an unexpected hydrogenation reaction at the last reductive aromatization step. Unusual Michael addition was observed on quinone 14, which was obtained by Diels-Alder reaction between 1 and 1,4-anthraquinone. Compounds 1-3 exhibited near-infrared (NIR) absorption and emission with high-to-moderate fluorescent quantum yields. Their structures and absorption spectra were studied by density function theory and non-planar twisted structures were calculated for 2 and 3. All compounds showed amphoteric redox behavior with multiple oxidation/reduction waves. Oxidative titration with SbCl(5)  gave stable radical cations, and the process was followed by UV/Vis/NIR spectroscopic measurements. Their photostability was measured and correlated to their different geometries and electronic structures.
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.
authors.forename: Jinling
authors.initials: J
authors.lastname: Li
authors.forename: Chongjun
authors.initials: C
authors.lastname: Jiao
authors.forename: Kuo-Wei
authors.initials: KW
authors.lastname: Huang
authors.forename: Jishan
authors.initials: J
authors.lastname: Wu
mesh_terms: D003500:Cyclization; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011084:Polycyclic Aromatic Hydrocarbons / Q000138:chemical synthesis* / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013056:Spectrophotometry, Ultraviolet; D019265:Spectroscopy, Near-Infrared
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; C570978:bisanthene