Could N-(diethylcarbamothioyl)benzamide be a good ionophore for sensor membranes?

Nuclear Magnetic Resonance, Density Functional Theory and Molecular Dynamics calculations together with X-ray diffraction analysis have been used to enlighten the structural properties of N-(diethylcarbamothioyl)benzamide, a ionophore for sensor applications. Focusing the attention over the molecular conformation in different phases – i.e. solid state, solution and gas – before and after the interaction with a heavy metal ion, the behaviour of the molecule as a ionophore in a typical Ion Selective Electrode membrane was simulated. The whole structural analysis has been carried out as a comparison with an already studied and similar compound also used for the same purpose. To achieve this goal the available single crystal structure has been used to model the X-ray powder diffraction pattern. Although the condensed phase structure was not used as a starting guess for the gas phase model, it fits the possible conformers suggested for the gas phase. As the structure transition solid → gas takes place with a substantial identity preservation, an analogous structure in the liquid phase was suggested. As a consequence, a detailed interaction mechanism between the title compound and the Pb2+ ion in solution has been depicted. Analogies and differences among the different structures and homologies with compounds of the same class, help the understanding of the ionophore behaviour in the electrode and its potential applications.