Boronic acid based modular fluorescent sensors for glucose

Modular photoinduced electron transfer (PET) sensors bearing two phenylboronic acid groups, one or two fluorophores: pyrene(a), phenanthrene(b), anthracene(c), 1-naphthalene(d), 2-naphthalene(e) and alkylene linkers, from trimethylene(3) to octamethylene(8), have been evaluated. Systems with a single pyrene fluorophore 34a, 35a and 36a bind the strongest with D-glucose (36a also binds well with D-melibiose). Whilst 37a and 38a bind the strongest with D-galactose. Changing the fluorophore, also, influences the binding, 36a, 36b and 36c are D-glucose selective, whilst 36d and 36e are D-galactose selective. Systems with two fluorophores 36a-a and 36a-b show an overall decrease in binding efficiency. Energy transfer in 36a-b results in enhanced sensitivity and selectivity towards D-glucose.