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 3(2+). 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 3(2+), 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.
Gadenne
Benoît
B
Dipartimento di Chimica "G. Ciamician", Università di Bologna, Via Selmi 2, 40126 Bologna (Italy), Fax: (+39) 051-209-9456.
Semeraro
Monica
M
Dipartimento di Chimica "G. Ciamician", Università di Bologna, Via Selmi 2, 40126 Bologna (Italy), Fax: (+39) 051-209-9456.
Yebeutchou
Roger M
RM
Dipartimento di Chimica Organica e Industriale and INSTM, UdR Parma, Università di Parma, Viale Usberti 17 A, 43100 Parma (Italy), Fax: (+39) 0521-905472.
Tancini
Francesca
F
Dipartimento di Chimica Organica e Industriale and INSTM, UdR Parma, Università di Parma, Viale Usberti 17 A, 43100 Parma (Italy), Fax: (+39) 0521-905472.
Pirondini
Laura
L
Dipartimento di Chimica Organica e Industriale and INSTM, UdR Parma, Università di Parma, Viale Usberti 17 A, 43100 Parma (Italy), Fax: (+39) 0521-905472.
Dalcanale
Enrico
E
Dipartimento di Chimica Organica e Industriale and INSTM, UdR Parma, Università di Parma, Viale Usberti 17 A, 43100 Parma (Italy), Fax: (+39) 0521-905472.
Credi
Alberto
A
Dipartimento di Chimica "G. Ciamician", Università di Bologna, Via Selmi 2, 40126 Bologna (Italy), Fax: (+39) 051-209-9456.