Synthesis of Trifluoromethyl Substituted Triphyrin, its Selective Reduction to Triphachlorin, and Stable Isomeric Triphabacteriochlorins via Direct De-trifluoromethylation

Two novel classes of reduced triphyrins, namely triphachlorin and triphabacteriochlorin are realized via selective reduc-tion 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 de-trifluoromethylation 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, 0.36) while generating singlet oxygen very efficiently (ϕΔ: 0.88, 0.86). These reduced porphyrinoids show very high oxidative stability as they remain unchanged upon refluxing with DDQ in toluene.