LOW BANDGAP LADDER POLYMERS

Unique new ladder polymers consisting of condensed succession of six a nd five membered conjugated carbon rings have been made recently by Sc herf and Mullen. Seven topological isomers of these polyindenoindenes are considered theoretically. The results are analyzed in terms of top ological bandgaps and geometry relaxation. Three isomers are expected to have a bandgap smaller than 0.2 eV, although the possibility of a f errimagnetic ground state for these can not be ruled out.