Premium
A Stable All‐Thiophene‐Based Core‐Modified [38]Octaphyrin Diradicaloid: Conformation and Aromaticity Switch at Different Oxidation States
Author(s) -
Ni Yong,
Gopalakrishna Tullimilli Y.,
Wu Shaofei,
Wu Jishan
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202000188
Subject(s) - dication , diradical , aromaticity , thiophene , antiaromaticity , delocalized electron , chemistry , crystallography , singlet state , molecule , dehydrogenation , photochemistry , atomic physics , excited state , physics , organic chemistry , catalysis
A soluble and stable core‐modified [38]octaphyrin, MC‐T8 , containing eight thiophene rings was synthesized by Yamamoto coupling followed by oxidative dehydrogenation. X‐ray crystallographic analysis revealed a nearly planar backbone, and the molecule is globally aromatic with a dominant 38π conjugation pathway. The dication MC‐T8 2+ is antiaromatic, and the backbone is distorted, with a different orientation of the thiophene rings. The tetracation MC‐T8 4+ becomes aromatic again, with a shallow‐bowl‐shaped geometry. Both the neutral compound and the dication demonstrated open‐shell diradical character with a small singlet–triplet energy gap (−2.70 kcal mol −1 for MC‐T8 and −3.78 kcal mol −1 for MC‐T8 2+ ), and they are stable owing to effective spin delocalization.