Unexpected formation of a triphyrin in the reaction of dibromodipyrromethene and N,N-dimethylaminoethanol

Abstract

A novel triphyrin was unexpectedly formed as a major by-product in the synthesis of meso-aryl-substituted dibenzo-5,10,15-triazaporphyrin from meso-aryl-substituted 1,9-dibromodipyrromethene and 5,6-diaryl-substituted 1,3-diiminoisoindoline in the presence of N,N-dimethylaminoethanol (DMAE). X-ray single crystal diffraction analysis elucidated that the terminal α-positions of this triphyrin were bridged by an N-methylaminoethoxy chain, which plausibly originated from DMAE during the reaction. The same compound was also obtained as a major product in the reaction of DMAE and meso-aryl-substituted 1,9-dibromodipyrromethene. Its unique properties, such as conformational flexibility of the bridging moiety and broad absorption in the visible region, were also revealed by 1 H NMR and UV-vis absorption spectroscopies.

Recent advances in subphthalocyanines and related subporphyrinoids

“…707 [22]Triphyrin(6.6.0) ( 740 ) and [22]Triphyrin(6.5.0) ( 741 ) represent examples of what has been called expanded porphyrin contraction. 708,709 In 742 one of the meso -units consists of an aminoethoxy moiety, 710 while [18]triphyrins(4.1.1) containing ethyne ( 743 and 744 ) 711–713 or butadiene 714 bridges have been reported. All of these structures contain completely different macrocyclic cores and hence, new and diverse coordination chemistry.…”

“…128) consist of a [18]triphyrin(6.1.1) structure, 706 while triphyrin 739 consists of a [15]triphyrin(1.1.3) derivative. 707 708,709 In 742 one of the meso-units consists of an aminoethoxy moiety, 710 while [18]triphyrins(4.1.1) containing ethyne (743 and 744) [711][712][713] Fig. 126…”

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.…”