Quantum-chemical studies of rutile nanoparticles toxicity I. Defect-free rod-like model clusters

TL;DR

This study uses semiempirical quantum-chemical methods to analyze the structure and toxicity of defect-free rutile nanoparticle models, revealing how specific titanium sites influence toxicity and stability.

Contribution

It introduces a detailed quantum-chemical analysis of rutile nanoparticle models, correlating Ti site coordination with toxicity and interaction energies.

Findings

Pentacoordinated Ti centers show maximal electron transfer to Cu2+.

Ti centers with most negative interaction energies are less toxic.

Nanoparticle destruction initiates at pentacoordinated Ti face centers.

Abstract

Using semiempirical PM6 method, the structures of a rod-like [Ti40O124H81]-7 model cluster and of the [Ti40O124H81Cu]-5 ones with Cu2+ coordinated at various sites were optimized. If the relative toxicity of individual Ti centers in rod-like rutile nanoparticles can be evaluated by the electron density transfer to a Cu2+ probe, its maximal values may be ascribed to the pentacoordinated corner and hexacoordinated edge ones with three Ti-OH bonds. However, these centers exhibit the least negative interaction energies which can be compensated by the significantly better accessibility of the corner Ti center in comparison with the remaining ones. The Ti centers with the most negative interaction energy parameters exhibit the lowest extent of the electron density transfer to a Cu2+ probe. The rutile nanoparticles destruction starts at pentacoordinated Ti face centers