Poly(thiophene-2,5-diyl)s with a Crown Ethereal Subunit. Preparation, Optical Properties, and n-Doped State Stabilized against Air

Five kinds of polythiophenes bearing a crown ethereal subunit directly bonded to the thiophene ring have been prepared by the following organometallic polycondensation: (i) n X−Ar−X + n Ni 0 L m → (̶Ar)̶ n; (ii) a X−Ar−X + b X−Ar‘−X + ( a + b )Ni 0 L m → (̶Ar) a (Ar‘)̶ b, and (iii) n X−Ar−X + n Me 3 Sn−Ar‘−SnMe 3 → (̶Ar−Ar‘)̶ n (Pd-catalyzed); Ar = thiophene-2,5-diyl with the crown ethereal subunit. Polythiophenes with alkoxy substituents (OCH 3 and O(CH 2 ) 2 OCH 3 ) are also prepared by the organometallic polycondensation. The crown ethereal polymers exhibit photoluminescence in a range of 467−603 nm in both CHCl 3 solutions and films. Their electroluminescence spectra essentially agree with the photoluminescence spectra. The crown ethereal polythiophenes have a high affinity toward Na + . After chemical oxidation (or p-doping) and reduction (or n-doping), the polymers show an electrical conductivity of 5.4 × 10 -7 to 1.8 S cm -1 . The Na-doped and electrically conducting state of crown ethereal polythiophenes shows some stability under air, which is attributed to the strong affinity of the polymer to Na + . Cyclic voltammetry of the crown and linear ethereal polythiophenes reveals a large difference (about 2 V) between n-doping and n-undoping potentials.