Transition-metal-based chemosensing ensembles: ATP sensing in physiological conditions

Sensing of biologically relevant anionic substrates in physiological conditions, employing the strategy of the chemosensing ensembles, is reported. Coordination of a fluorescent indicator to a dicopper(II) polyazamacrocyclic receptor ([Cu-2(L)]) results in the collapse of its fluorescence emission. Competitive binding of substrates for the receptor releases the indicator in solution, with full emission recovery. The spectral changes obtained for some indicators and substrates were analysed to determine their respective association constants for the receptor. Discrimination of micromolar ATP quantities from other interferents (small inorganic anions and well-known neurotransmitters) is improved by a judicious choice of the indicator, the resulting ATP sensor promising interesting biological applications.