Synthesis of Highly Soluble and Oxidatively Stable Tetraceno[2,3-b]thiophenes and Pentacenes

A comparative study of suitably functionalized, highly soluble tetraceno[2,3-b]thiophenes (13) and pentacenes (46) that show higher photoxidative stability than that of unfunctionalized corresponding acenes is reported. The absorption and emission of 13 (Amax = 624−656 nm, λmax = 634−672 nm, ΦF ≈ 10%) and 46 (Amax = 672−704 nm, λmax = 682−718 nm, ΦF ≈ 10%) were found to be systematically red-shifted by the substitution in the order of the tert-butylethynyl < triisopropylsilylethynyl < phenylethynyl groups. The oxidation potentials of these compounds were similar (E1/2 ≈ 0.70 V), except for 4, which showed lower oxidation potential (E1/2 ≈ 0.63 V).