A Conducting Poly(cyclophane) and Its Poly([2]-catenane).

Cyclization of 1,4-Bis[2-(2-(2-(2-toluene-p-sulfonylethoxy) ethoxy) ethoxy) ethoxy]benzene with 1,4-diiodo-2,5-dihydroxybenzene, followed by coupling with (3,4-ethylenedioxy)-thiophene produced 1,4-Bis((3,4-ethylenedioxy)thiophene)-7,10,13,16,19,26,29,32,35,38-decaoxa[13.13]paracyclophane (I) a highly fluorescent electropolymerizable monomer and electron donor. Addn. of Paraquat to I in CH3CN resulted in formation of a deep-green colored soln. with a charge-transfer absorption band at $łambda$ = 589 nm ($ε$ = 204 M-1cm-1), indicative of the highly electron-donating nature of the thiophene-phenylene-thiophene arom. scaffold. The tetrakis-hexafluorophosphate I-[2]-catenane complex (II) was prepd. by reaction of I with NH4PF6 and 1,4-bis(bromomethyl)benzene. The deep-green complex II exhibits a charge-transfer absorption at $łambda$ = 626 nm ($ε$ = 1230 M-1 cm-1), which is red-shifted relative to that of Paraquat:I complex indicating greater intimacy between donor and acceptor in the [2]-catenane. The crystal structure of II indicates an interlocked $π$-stacked geometry with inner bipyridinium moieties within the cyclophane cavity and outer bipyridinium on the periphery of the cavity. Electrochem. polymn. of I and II proceeds via two propagating sites at the 5-position of 3,4-ethylenedioxythiophene and affords conducting polymers. Oxidn. and redn. potentials for poly-II are identical to those of II monomer suggesting that the neutral polymer backbone has the same electronic influence as the thiophene-phenylene-thiophene in II. For both poly-I and poly-II, the multiple redn. peaks obsd. are indicative of the energetic inequality between the inner- and outer-bipyridinium groups. The cond. of poly-II rapidly reaches a max. of 0.2 S/cm at 0.12 V vs. Fc/Fc+, which decays quickly thereafter. In contrast, the cond. profile for poly-I shows that oxidn. of the backbone occurs over a broad range of potentials without decay. The absorption spectra of both conducting polymers are similar; in the neutral (insulating) form, the $łambda$max for poly-I was 527 nm (2.35 eV) and poly-II 542 nm (2.29 eV). When oxidatively doped, both displayed a longer wavelength band at 767-796 nm (1.62-1.56 eV), indicative of new states formed within the band gap upon reaching a conductive state. Further lower energy absorptions occur at higher oxidn. potentials leading to an absorption at >1100 nm (>1.13 eV) owing to the formation of free carriers. The films differ in that poly-II requires higher oxidn. potentials to reach its conductive state than does poly-I. [on SciFinder(R)]