title: A Molecular Nanotube with Three-Dimensional π-Conjugation.
abstract: 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 C-C 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.
authors.affiliation: Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, OX1 3TA (UK) http://hla.chem.ox.ac.uk/
authors.forename: Patrik
authors.initials: P
authors.lastname: Neuhaus
authors.affiliation: Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, OX1 3TA (UK) http://hla.chem.ox.ac.uk/
authors.forename: Arjen
authors.initials: A
authors.lastname: Cnossen
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU (UK).
authors.forename: Juliane Q
authors.initials: JQ
authors.lastname: Gong
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU (UK).
authors.forename: Laura M
authors.initials: LM
authors.lastname: Herz
authors.affiliation: Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, OX1 3TA (UK) http://hla.chem.ox.ac.uk/. harry.anderson@chem.ox.ac.uk.
authors.forename: Harry L
authors.initials: HL
authors.lastname: Anderson
keywords: fluorescence anisotropy; nanotubes; polycycles; synthetic methods; template synthesis