Visible and Near-Infrared Absorbing, Low Band Gap Conjugated Oligomers Based on Cyclopentadieneones

Abstract

Three polymers based on tetraarylcyclopentadienone were synthesized and found to have band gaps between 1.5 and 0.9 eV by cyclic voltammetry and absorption spectroscopy. Chemical oxidative polymerization with ferric chloride was carried out to yield as an intractable black powder. A 4-heptylphenyl group was substituted at the most remote position of the fluoranthene moiety to improve solubility. The polymerization of CPD derivative was accomplished using ferric chloride. The diphenyl derivative, was synthesized in order to create a polymer that would retain the ability to absorb a large portion of the visible spectrum. Proton NMR spectroscopy of the polymers revealed very broad aromatic peaks that were likely the result of aggregation. Solid state ESR revealed one narrow peak with a g-value of 2.0024 and one broad peak with a g-value of 2.0353.