Electrochemically Controlled Formation/Dissociation of Phosphonate-Cavitand/Methylpyridinium Complexes

The phosphorus‐bridged cavitand 1 self‐assembles very efficiently in CH2Cl2 with either the monopyridinium guest 2+ or the bispyridinium guest 32+. In the first case a 1:1 complex is obtained, whereas in the second case both 1:1 and 2:1 host–guest complexes are observed. The association between 1 an...

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Bibliographic Details
Published in:Chemistry : a European journal 2008-10, Vol.14 (29), p.8964-8971
Main Authors: Gadenne, Benoît, Semeraro, Monica, Yebeutchou, Roger M., Tancini, Francesca, Pirondini, Laura, Dalcanale, Enrico, Credi, Alberto
Format: Article
Language:English
Subjects:
Adducts
cavitands
Complexation
Control systems
electrochemistry
Electrode potentials
Fluorescence
host-guest systems
luminescence
Phosphonates
Reduction
Stimuli
supramolecular chemistry
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Summary:The phosphorus‐bridged cavitand 1 self‐assembles very efficiently in CH2Cl2 with either the monopyridinium guest 2+ or the bispyridinium guest 32+. In the first case a 1:1 complex is obtained, whereas in the second case both 1:1 and 2:1 host–guest complexes are observed. The association between 1 and either one of the guests causes the quenching of the cavitand fluorescence; in the case of the adduct between 1 and 32+, the fluorescence of the latter is also quenched. Cavitand complexation is found to affect the reduction potential values of the electroactive guests. Voltammetric and spectroelectrochemical measurements show that upon one‐electron reduction both guests are released from the cavity of 1. Owing to the chemical reversibility of such redox processes, the supramolecular complexes can be re‐assembled upon removal of the extra electron from the guest. Systems of this kind are promising for the construction of switchable nanoscale devices and self‐assembling supramolecular materials, the structure and properties of which can be reversibly controlled by electrochemical stimuli. Be my guest…︁ but take care not to get a shock! A phosphonate cavitand forms remarkably stable inclusion complexes with mono‐ and bispyridinium species in dichloromethane. Such complexes can be disassembled and re‐assembled under electrochemical control by the reversible one‐electron reduction/oxidation of the guest (see graphic).
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.200800966