Mechanism of Binding of Hydrated Titanium Dioxide Nanocluster with Calcium Aqua Ion

The equilibrium geometry and wave functions were calculated and a quantum topological study of electron density was performed for the supramolecular complexes [Ca(H₂O)₆]²⁺[(TiO₂)_n] (n = 1, 10‒16) and [Ca(H₂O)₆]²⁺[(TiO₂)₁₀(H₂O)_m] (m = 2, 8–10) with different numbers of water molecules in the hydration shell of the (TiO₂)₁₀ cluster using the density functional theory method in the B3LYP/6-31g(d, p) approximation. The binding of the calcium aqua ion with isolated (TiO₂)_n or hydrated (TiO₂)₁₀ mainly occurs due to the formation of OH···O intermolecular hydrogen bonds of the water molecules of the hydration shell of [Ca(H₂O)₆]²⁺ with the oxygen atoms of the titanium dioxide cluster. The energies of H bonds between the calcium aqua ion and the titanium dioxide nanocluster were calculated, and the bonds were shown to have high dynamic stability.