The phosphorus-bridged cavitand 1 self-assembles very efficiently in CH2C12 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.
Electrochemically Controlled Formation/Dissociation of Phosphonate Cavitand-Methylpyridinium Complexes / B., Gadenne; M., Semeraro; R. M., Yebeutchou; Tancini, Francesca; Pirondini, Laura; Dalcanale, Enrico; A., Credi. - In: CHEMISTRY-A EUROPEAN JOURNAL. - ISSN 0947-6539. - 14:29(2008), pp. 8964-8971. [10.1002/chem.200800966]
Electrochemically Controlled Formation/Dissociation of Phosphonate Cavitand-Methylpyridinium Complexes
TANCINI, Francesca;PIRONDINI, Laura;DALCANALE, Enrico;
2008-01-01
Abstract
The phosphorus-bridged cavitand 1 self-assembles very efficiently in CH2C12 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.