Molecular and supramolecular characterization of Ni(II)/losartan hydrophobic nanoprecipitate

•Paramagnetic complex has a D4h geometry around the metallic center.•Complexation is a stepwise process.•Ni(II)/Los spontaneously aggregates into hydrophobic nanoprecipitate (HnP).•Particles are stabilized in suspension by excess of Los− anion.•HnP are rigid and spherical particles, which do not disaggregate upon shearing..

In this work, a contribution to understanding of the formation of metal(II)/losartan hydrophobic nanoprecipitate is reported. A Ni(II)/Los system was prepared and characterized in solid state and in solution. Solubility studies confirmed the formation of hydrophobic precipitate. Obtained spectroscopic data suggest a sort of coordination between tetrazolic ring as well as OH, and a D4h geometry around the nickel cation. Thermodynamic studies demonstrated that complexation is a stepwise process, with equal enthalpic and entropic contributions for free energy of complexation. DLS and zeta potential titrations indicate the formation of stable nanoparticles of size and charge dependent on the molar ratio. Finally, rheological studies demonstrate a Bingham plastic behavior for Ni(II)/Los suspension.

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