This change has been first explored
by Singaram and collaborators and recently published in a
brief communication [15]. In their study, they used a dicationic
benzyl viologen quencher functionalized with boroin acids groups
(o-BV2+, Fig. 1) to quench, by photoinduced electron transfer, the
emission of an anionic pyrene derivative following an electrostatic
interaction between the two species. In presence of sugar, a neutral
zwiterionic quencher is formed (C, Scheme 1), which drawback the
formation of complexation between the quencher and the fluorescent
probe, and then remove the quenching effect. Using this
mechanism, large intensity change can be obtained. Singaram
et al. reported intensity increases up to 5-fold using an anionic pyrene
derivative, while we reported intensity increases up to 70-fold
using an anionic conjugated polymer [17].