Layered silicate stabilises diiron to mimic UV-shielding TiO2 nanoparticle

Abstract

Despite the ubiquity of aqua-Fe(III) complexes in biological enzymes and their useful properties and cost-effectiveness, artificially stabilizing these fleeting molecules for practical uses remains challenging. Herein, we demonstrate that a dimeric aqua-Fe(III) species can be stabilised using a flexible microporous layered silicate to produce a white UV-absorbing powder with significantly reduced undesirable photocatalytic activity. A mixture of this powder material and a natural oil is successfully employed to shield a UV-sensitive substrate; its shielding performance was comparable to that of a commercial-TiO(2)( )rutile coating. Comprehensive analyses and calculations reveal that a dihydroxo-bridged dimer, [(H2O)(OH)(2)O5FeIII(OH)(2)(FeOS)-O-III(H2O) (OH)(2)] (O-S: framework oxygen), fits the silicate pore and account for the stabilities and shielding properties of the material. Although TiO2 nanoparticles are widely used as UV absorbers in sunscreens and cosmetics, they pose health risks owing to their cytotoxicity. Thus, this material can serve as a safe, cost-effective alternative to TiO2 nanoparticles, either as a UV absorber or in other applications.