Redox Switching of Conjugation Length Using 9,9,10,10-Tetraaryl-9,10-dihydrophenanthrene as an ON/OFF Unit: Preparation, X-ray Structure, and Redox Properties of Perfluorobiphenyl Derivative and Its SNAr Reactions to π-Extended Analogues
Redox Switching of Conjugation Length Using 9,9,10,10-Tetraaryl-9,10-dihydrophenanthrene as an ON/OFF Unit: Preparation, X-ray Structure, and Redox Properties of Perfluorobiphenyl Derivative and Its S<sub>N</sub>Ar Reactions to π-Extended Analogues
Octafluorobiphenyl-2,2′-diylbis(diarylmethylium) dye 2a2+ prepared from 1,2-dibromotetrafluorobenzene is interconvertible with colorless dihydrophenanthrene donor 1a. By the SNAr reactions of 1a with acetylides, π-extended analogues 1b and 1c were obtained. Their electrochromic behavior is accompanied by a drastic absorption change not only in the visible but also UV region, because the torsion angle of the biaryl unit is modified upon redox reactions.
dihydrophenanthrene-type electron donor are interconvertible upon two-electron transfer. Redox-triggered C-C bond-formation/cleavage caused a drastic change in the torsion angle of the biphenyl unit. Thus, π-delocalization ON/OFF switching was observed as a change in the UV absorption upon electrolysis of the linearly extended analogue with two phenylethynyl groups. A further extended π-system with a molecular length