Construction of Donor–Acceptor Chromophores in Platinum Polyyne Polymer by [2 + 2] Cycloaddition of Organic Acceptors

A thiophene-containing platinum polyyne polymer was postfunctionalized by a [2 + 2] cycloaddition followed by a cycloreversion of tetracyanoethylene (TCNE) or 7,7,8,8-tetracyanoquinodimethane (TCNQ), yielding narrow band gap polymers. The quantitative addition of the acceptor molecules was confirmed by combined analytical techniques. The postfunctionalized platinum polyyne polymers displayed charge-transfer (CT) bands in the visible-near IR region and potent redox activities. The TCNQ adduct has a stronger electron-accepting feature than the TCNE adduct, as revealed by the more bathochromically shifted CT band and the lower first reduction potential. The systematic investigation revealed a clear correlation between the optical and electrochemical band gaps.