Analysis of the role of the pH in the anchoring of alkylphosphonic acid on a TiO2 surface: A DFTB study

The reactivity of a (1 1 0) rutile titanium dioxide surface functionalized with neutral, anionic and di-anionic forms dodecyl-phosphonic acid was studied by Density Functional based Tight Binding theory to simulate different pH conditions. Functionalization this is relevant for at least two reasons: a) protect the against external agents (e.g., preventing proliferation bacteria in medical implants) b) use these organic–inorganic hybrid materials facilitate anchoring other molecules. Comparing results obtained gas phase water, experimental findings are better modelled considering hydration energy acids solvation-desolvation process involving surface. In all protonation states, molecules interact hydrated as mono-negative charged species due proton transfer before grafting process. formation bi-dentate, species, or change pH, favoured alkylphosphonic rutile.