title: The phane properties of anti-[2.2](1,4)biphenylenophane.
abstract: [structure: see text] Anti-[2.2](1,4)biphenylenophane (4) was synthesized from de Meijere's tetrabromo[2.2]paracyclophane (5) through a four-step reaction sequence. Although an average separation of 3.09 A between the inner ring of the biphenylene units is normal for [2.2]paracyclophanes, a bond distance of 1.54 Afor the ethano C-C bridge at room temperature is shorter than usual. In addition, trimethylsilyl-substituted anti-[2.2](1,4)biphenylenophane 8 sublimes at 220 degrees C under a pressure lower than 1 x10(-5) Torr without decomposition or thermal isomerization. The high thermal stability of 8 suggested that the ethano bridges of the biphenylenophanes are less strained than those of [2.2]paracyclophane. Bathochromic shifts are observed in their UV-vis absorption spectra. The phane state interactions of 4 and 8 were evidenced by the weak structureless fluorescent emission maximized at 537 and 550 nm in CH(2)Cl(2) along with longer relaxation lifetimes of 229 and 292 ps, respectively.
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, Taiwan 106. mkleung@ntu.edu.tw
authors.forename: Man-kit
authors.initials: MK
authors.lastname: Leung
authors.forename: M Balaji
authors.initials: MB
authors.lastname: Viswanath
authors.forename: Pi-Tai
authors.initials: PT
authors.lastname: Chou
authors.forename: Shih-Chieh
authors.initials: SC
authors.lastname: Pu
authors.forename: Hsin-Chieh
authors.initials: HC
authors.lastname: Lin
authors.forename: Bih-Yaw
authors.initials: BY
authors.lastname: Jin