Bile acid derived PET-based cation sensors: molecular structure dependence of their sensitivity

A number of bile acid derived photoinduced electron transfer (PET) based sensors for metal ions are prepared. A general strategy for designing the sensor with a modular nature allows for making different molecules capable of sensing different metal ions by a change in the fluorophore and receptor unit. Keeping the basic molecular structure the same, different bile acid based fluoroionophores were prepared in order to achieve the highest sensitivity toward the metal ions. The sensors showed similar binding constants for the same metal ion, but the degree of fluorescence enhancement upon addition of the metal salts were different. The sensitivities of the sensors towards a certain metal were determined from the observed fluorescence enhancement upon addition of the metal salt.