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 CF 3 moiety to form two isomeric triphabacteriochlorins 3 and 4, which exhibit blue-shifted intense lowest-energy absorption bands and intense emission (ϕ f = 0.52 and 0.36, respectively) while generating singlet oxygen very efficiently (ϕ Δ = 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.

Synthesis of unsymmetrical 2,3,7,8-tetrabromo meso-5,10,11,16-tetraaryl- triphyrin(2.1.1) and its use in the synthesis of sterically crowded 2,3,5,7,8,10,11,16-octaarylated triphyrin(2.1.1)s

“…However, the chemistry of triphyrin(2.1.1) has been limited until recently due to the inaccessibility of proper synthetic routes. We [15][16][17][18][19][20][21] and others [22][23][24] have developed much simpler, straight-forward synthetic routes for meso-tetraaryl triphyrin(2.1.1) 1 (Chart 1) using readily available precursors. We also developed conditions to introduce bromines regioselectively at the β-pyrrole carbons and successfully synthesized β-monobromo to β-hexabromo triphyrins 2-7 (Chart 1) under simple reaction conditions.…”