Donor-acceptor interactions in organometallic and organic poly-ynes

The donor-acceptor interactions in organic polyene were investigated using the spacers between the acetylenic units as acceptors and an electron-rich transition metal platinum or an alkoxy-substituted phenyl ring as donors. The fluorine-substituted phenyl ring was too weak an acceptor to cause a donor-acceptor interaction with the platinum ion. The donor-acceptor interaction present in the thieno-pyrazine unit was enhanced by the electron system in the polymer backbone which caused a charge-transfer transition which lowers the optical gap from 3.0 eV to 1.7 eV. The decoupling between the first and second excited state was strong enough to allow emission from the second excited state.