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Conformational Effects of Bay Substituents on Optical, Electrochemical and Dynamic Properties of Perylene Bisimides: Macrocyclic Derivatives as Effective Probes
Author(s) -
Osswald Peter,
Würthner Frank
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200700601
Subject(s) - perylene , chemistry , structural isomer , fluorescence , cyclic voltammetry , proton nmr , photochemistry , homo/lumo , fluorescence spectroscopy , spectroscopy , electrochemistry , molecule , stereochemistry , crystallography , organic chemistry , physics , electrode , quantum mechanics
Abstract A series of diagonally and laterally bridged regioisomeric macrocycles based on 1,6,7,12‐tetraaryloxy‐substituted perylene bisimides (APBIs) have been synthesized and characterized. The different orientations of the aryloxy residues, that is, horizontal or perpendicular to the perylene core, in the regioisomeric macrocycles have been elucidated by NMR spectroscopy, and the dynamic properties of the laterally bridged regioisomers have been investigated by temperature‐dependent NMR measurements. The influence of the different orientations of the aryloxy substituents on the electrochemical properties of APBIs is demonstrated by cyclic voltammetry, which reveals that a perpendicular orientation of the aryloxy residues relative to the perylene core leads to a substantial decrease of the LUMO energy level of the perylene bisimide electrophore. The optical properties of the regioisomeric macrocycles have been determined by UV/Vis and fluorescence spectroscopy. It has been shown that the diagonally bridged macrocycles exhibit optical properties that differ significantly from those of an open‐chain reference compound, whereas the optical properties of the laterally bridged isomers resemble those of the reference system. This demonstrates that unrestricted aryloxy substituents prefer the lateral conformation in solution. Solvent‐dependent fluorescent properties have been exemplified for one diagonally bridged derivative, suggesting a photoinduced electron transfer process as fluorescence quenching mechanism for APBIs. From these investigations, guidelines toward highly fluorescent APBI dyes in polar media could be derived.