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An Ethyne‐Bridged Porphyrin‐Hexaphyrin‐Porphyrin Triad That Undergoes a Thermal Transannular Cyclization
Author(s) -
Honjo Kazuma,
Mori Hirotaka,
Osuka Atsuhiro
Publication year - 2016
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.201500509
Subject(s) - porphyrin , chemistry , triad (sociology) , photochemistry , conjugated system , proton nmr , stereochemistry , organic chemistry , polymer , psychology , psychoanalysis
An ethyne‐bridged Ni 2+ porphyrin‐[26]hexaphyrin‐Ni 2+ porphyrin triad ( 4 ) has been prepared and shown to adopt a dumbbell‐like conformation despite the two bulky porphyrinylethynyl groups at the hinge positions of the hexaphyrin. The 1 H NMR and UV/vis/NIR spectra of 4 revealed that the aromatic nature of the [26]hexaphyrin unit was significantly mitigated via conjugative interaction with the porphyrinylethynyl substituents. Thermal transannular cyclization of 4 proceeded smoothly to give vinylene‐bridged triad 12 , in which the π‐systems of the Ni 2+ porphyrins and [26]hexaphyrin are not conjugated and the aromatic character of the latter is enhanced.