Synthesis of Trifluoromethyl-Substituted [14]Triphyrin(2.1.1), Its Selective Reduction to Triphachlorin, and Stable Isomeric Triphabacteriochlorins via Direct Detrifluoromethylation.

Abstract

Two novel classes of reduced triphyrin(2.1.1), namely, triphachlorin and triphabacteriochlorin, are realized via selective reduction of the newly synthesized 7,12-bis(trifluoromethyl)triphyrin(2.1.1) 1 using p-tosylhydrazide. Triphachlorin 2 displayed red-shifted absorption (580 nm). Harsher conditions, however, led to a unique direct detrifluoromethylation of one CF3 moiety to form two isomeric triphabacteriochlorins 3 and 4, which exhibit blue-shifted intense lowest-energy absorption bands and intense emission (ϕf = 0.52 and 0.36, respectively) while generating singlet oxygen very efficiently (ϕΔ = 0.88 and 0.86, respectively). These reduced porphyrinoids show very high oxidative stability as they remain unchanged upon refluxing with 2,3-dichloro-5,6-dicyanobenzoquinone in toluene.