Highly Conjugated π-Electron Donor and π-Electron Acceptor Dimers with <i>p</i>-Quinodimethane Structures
作者:Nazario Martín、Ignacio Pérez、Luis Sánchez、Carlos Seoane
DOI:10.1021/jo961795o
日期:1997.2.1
The syntheses of the first dimeric donors (19a-c) derived from TTF with p-quinodimethane structures as well as the analogues dimeric accepters (20, 21) derived from TCNQ and DCNQI have been carried out from the novel 2,2'-oxydianthraquinone (18). Depending upon the substitution pattern on the 1,3-dithiole ring of the donor molecules, eight (19a) or sixteen (19b and 19c) sulfur atoms are contained in these dimers. The presence of the oxygen atom connecting both monomeric units has an influence on the redox properties of the novel dimers due to its electron-withdrawing effect. The CV data indicate that these dimers behave electrochemically as two independent monomers. This behavior de tines rather unusual electrochemical properties in both donor (19a-c) and acceptor (20) molecules, which exhibit only one redox wave involving a four-electron overall process. In contrast, the dimeric DCNQI derivative (21) showed two-electron reduction waves to form, simultaneously in both monameric units, the radical anions and dianions. The redox potential values show that although the dimeric accepters 20 and 21 exhibit too negative potentials to form stable solid CT-complexes with donor molecules, the novel dimeric donors show a donating ability similar to that of BEDT-TTF. The dimeric donors (19a-c) did not form CT-complexes with TCNQ and DCNQI due to their distorted structures, but they form CT-complexes with stronger acceptor molecules such as TCNQF(4) and DDQ. These CT-complexes, which showed in all cases a 1:3 (donor:acceptor) stoichiometry, exhibit a paramagnetic and semiconducting electrical behavior.