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Proton‐ and Redox‐Controlled Switching of Photo‐ and Electrochemiluminescence in Thiophenyl‐Substituted Boron–Dipyrromethene Dyes
Author(s) -
Röhr Holger,
Trieflinger Christian,
Rurack Knut,
Daub Jörg
Publication year - 2006
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.200500729
Subject(s) - electrochemiluminescence , boron , photochemistry , redox , proton , chemistry , materials science , inorganic chemistry , organic chemistry , physics , electrode , quantum mechanics
A luminescent molecular switch in which the active thiol/disulfide switching element is attached to a meso ‐phenyl‐substituted boron–dipyrromethene (BDP) chromophore as the signalling unit is presented. The combination of these two functional units offers great versatility for multimodal switching of luminescence: 1) deprotonation/protonation of the thiol/thiolate moiety allows the highly fluorescent meso ‐ p ‐thiophenol‐BDP and its nonfluorescent thiolate analogue to be chemically and reversibly interconverted, 2) electrochemical oxidation of the monomeric dyes yields the fluorescent disulfide‐bridged bichromophoric dimer, also in a fully reversible process, and 3) besides conventional photoexcitation, the well separated redox potentials of the BDP also allow the excited BDP state to be generated electrochemically (i.e., processes 1) and 2) can be employed to control both photo‐ and electrochemiluminescence (ECL) of the BDP). The paper introduces and characterizes the various states of the switch and discusses the underlying mechanisms. Investigation of the ortho analogue of the dimer provided insight into potential chromophore–chromophore interactions in such bichromophoric architectures in both the ground and the excited state. Comparison of the optical and redox properties of the two disulfide dimers further revealed structural requirements both for redox switches and for ECL‐active molecular ensembles. By employing thiol/disulfide switching chemistry and BDP luminescence features, it was possible to create a prototype molecular ensemble that shows both fully reversible proton‐ and redox‐gated electrochemiluminescence.