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Abstract
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The density functional theory (DFT) calculations were used to get information concerning
the interaction of curcumin with pristine and N-doped TiO 2 anatase nanoparticles. Three
adsorption geometries of curcumin over the TiO 2 anatase nanoparticles were studied in order
to fully exploit the sensing properties of TiO 2 nanoparticles. Curcumin molecule adsorbs on
the fivefold coordinated titanium sites of the TiO 2 nanoparticle because of the high affinity of
these sites with respect to the curcumin molecule. A preferred perpendicular adsorption of
curcumin on the OC-substituted nanoparticle was found to be the most favorable conformation
with the estimated adsorption energy of about -5.33 eV. The results suggest that the curcumin
molecule favorably interacts with the N-doped TiO 2 nanoparticle, that is, the interaction of
curcumin with the pristine nanoparticle is less favorable in energy than the interaction with
the N-doped one. The structural parameters such as bond lengths/angles and adsorption
energies were examined in the discussion of results. The electronic structures of the system
were analyzed in view of the density of states and molecular orbitals. The analysis of projected
density of states and molecular orbitals showed forming new chemical bonds between the
nanoparticle and curcumin molecule. By including vdW interactions, the adsorption energies
of the most stable curcumin+TiO 2 couples were increased, implying the dominant effect of
dispersion energy.
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