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Nonplanar Porphyrins by N ‐Substitution: A Neglected Pathway
Author(s) -
Roucan Marie,
Flanagan Keith J.,
O'Brien John,
Senge Mathias O.
Publication year - 2018
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201800960
Subject(s) - chemistry , porphyrin , substitution (logic) , stereochemistry , nuclear magnetic resonance spectroscopy , structural isomer , crystallography , organic chemistry , computer science , programming language
N ‐substitution of porphyrins has been a neglected route towards nonplanar porphyrins for the past decades. Previously, they featured in a host of potential medicinal and biochemical applications. However, tailored syntheses of N ‐methylated porphyrins, improvements of synthetic methodology, or full conformational analyses were lacking since the initial studies. Here we investigated and optimized synthetic pathways to generate specific N ‐methylated porphyrins exclusively and in good yields. Full characterizations of the spectroscopy and structural properties associated with the insertion of different numbers of methyl into the porphyrin core of 5,10,15,20‐tetrasubstituted A 4 ‐ and 5,15‐disubstituted A 2 ‐type porphyrins was carried out by using UV/Vis, NMR, and X‐ray crystallographic techniques. The latter, in conjunction with detailed normal structural decomposition analyses, identified the structural consequences of number and isomeric pattern of N ‐methylation in terms of macrocycle nonplanarity and the underlying out‐of‐plane and in‐plane distortion modes.