Premium
5,10,15,20‐Tetraphenylsapphyrin‐Identification of a Pentapyrrolic Expanded Porphyrin in the Rothemund Synthesis
Author(s) -
Chmielewski Piotr J.,
LatosGrażyński Lechoslaw,
Rachlewicz Krystyna
Publication year - 1995
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.19950010111
Subject(s) - pyrrole , porphyrin , tetraphenylporphyrin , chemistry , condensation , molecule , ring (chemistry) , stereochemistry , benzaldehyde , nucleus , crystallography , photochemistry , organic chemistry , catalysis , physics , biology , thermodynamics , microbiology and biotechnology
The Rothemund‐type condensation of pyrrole and benzaldehyde yields, apart from 5,10,15,20‐tetraphenylporphyrin (TPPH 2 ) and inverted tetraphenylporphyrin 2‐aza‐21‐carba‐5,10,15,20‐tetraphenylporphyrin (CTPPH 2 ), a unique pentapyrrolic macrocyclic molecule with the aromatic nucleus of sapphyrin, namely, 5,10,15,20‐tetraphenylsapphyrin (TPSH 3 ). Its unorthodox structural skeleton with an inverted pyrrole ring lying opposite to the bipyrrole unit accounts for the spectroscopic properties of the novel sapphyrin. The diprotonation of TPSH 3 acts as a trigger for a structural transformation involving a flip of the pyrrole units, which relocates the 27‐NH pyrrolic nitrogen from the periphery into the center of the macrocycle. The formation of 5,10,15,20‐tetraphenylsapphyrin proves that the pentapyrrolic product is accessible by the mechanism of the Rothemund synthesis.