Thermodynamic parameters for the formation of simple copper(II) and zinc(II) complexes with adenosine 5′-triphosphate (ATP), L-tryptophanate (trpO), and L-alaninate (alaO) were determined by means of potentiometric and calorimetric measurements. Detailed analysis of the potentiometric data allowed reliable values of stability constants to be obtained. For the first time, the thermodynamic functions for the [M₂(ATP)] species are also reported. On the basis of ΔH^⊖ and ΔS^⊖ changes, the structure, in aqueous solution, of the main species present in the M–ATP systems are discussed. The ΔG^⊖, ΔH^⊖, and ΔS^⊖ values for the [M(ATP)L]^3– mixed-ligand complex (L = amino-acid anion) were also determined. The larger positive AHe and the less positive ΔS^⊖ accompanying formation of [M(ATP)(trpO)]^3– compared with [M(ATP)(alaO)]^3– are considered to indicate the presence of ligand–ligand interaction in the former complex. Further support for this is gained by comparing the differences between the ΔH^⊖ and ΔS^⊖values for formation of [Cu(ATP)(trpO)]^3– and [Zn(ATP)(trpO)]^3– and those for [Cu(ATP)(alaO)]^3– and [Zn(ATP)(alaO)]^3–. The presence of the stacking interaction is also discussed in relation to the geometric requirements of the metal ions.

A new turn-on Cu²⁺ fluorescent sensor (CST) having a trehalose moiety, which confers a relatively large solubility in water, has been synthesized. The chemosensor is therefore suitable for studies in aqueous solution. Full potentiometric and UV-vis characterization evidence that at physiological pH CST forms with Cu²⁺ a species with a 1 : 1 stoichiometry allowing for a straightforward correlation between CST response and copper(II) concentration. The presence of the trehalose unit does not negatively affect the selectivity of CST for Cu²⁺ over a series of metal ions of interest as proven by fluorescence measurements. The novel chemosensor, tested in differentiated neuroblastoma SH-SY5Y cells, is able to detect Cu²⁺ in the extracellular region, as well as to track copper transfer processes upon cell stimulation induced by cellular depolarization.