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A Molecular Nanotube with Three‐Dimensional π‐Conjugation
Author(s) -
Neuhaus Patrik,
Cnossen Arjen,
Gong Juliane Q.,
Herz Laura M.,
Anderson Harry L.
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201502735
Subject(s) - delocalized electron , porphyrin , excited state , nanotube , conjugated system , photochemistry , fluorescence , quantum yield , fluorescence anisotropy , fluorescence spectroscopy , spectroscopy , chemistry , absorption spectroscopy , materials science , crystallography , molecular physics , nanotechnology , atomic physics , optics , carbon nanotube , polymer , organic chemistry , physics , quantum mechanics
A π‐conjugated twelve‐porphyrin tube is synthesized in 32 % yield by a template‐directed coupling reaction that joins together six porphyrin dimers, forming twelve new CC bonds. The nanotube has two bound templates, enclosing an internal volume of approximately 4.5 nm 3 . Its UV/Vis/NIR absorption and fluorescence spectra resemble those of a previously reported six‐porphyrin ring, but are red‐shifted by approximately 300 cm −1 , reflecting increased conjugation. Ultrafast fluorescence spectroscopy demonstrates extensive excited‐state delocalization. Transfer of electronic excitation from an initially formed state polarized in the direction of the nanotube axis ( z axis) to an excited state polarized in the xy plane occurs within 200 fs, resulting in a negative fluorescence anisotropy on excitation at 742 nm.