Size‑, Mass‑, and Density-Controlled Preparation of TiO₂ Nanoparticles in a Spherical Coordination Template

TiO₂ nanoparticles were prepared with strict control of the size, molecular mass (PDI = 1.02), and mass density by hydrolyzing a precursor, Ti­(acac)₂(biphen), in the presence of a well-defined hollow Pd₁₂L₂₄ spherical endotemplate. The formation of highly monodisperse TiO₂ nanoparticles was confirmed by ¹H NMR spectroscopy, MALDI–TOF mass spectrometry, transmission electron microscopy, and atomic force microscopy. The template was easily removed by treating the sphere with a metal scavenger followed by calcination to give crystalline TiO₂ nanoparticles (2.0 ± 0.2 nm in diameter), which showed photocatalytic activity