Modification of hollow core-shell particles with poly (amino) acids to induce chirality

Due to the potential environmental applications, photocatalytic reactions occurring on the surface of photoirradiated titanium (IV) oxide (TiO₂) have garnered a wide interest. Despite displaying high photocatalytic activity, the utilization of TiO₂ is limited by its lack of selectivity. This paper presents the synthesis of platinized TiO₂ core and hollow silica shell (SiO₂/void/Pt-TiO₂), with the silica pores modified with chiral agents, namely poly (amino acid)s. The fabrication of the composite is firstly done by modifying the surface of TiO₂ powder with amino groups using 3-amino-propyltrimethoxysilane (APS).The resulting material and platinized TiO₂ is tested out in the photocatalytic redox-combined synthesis of L-PCA (pipecolinic acid) from (racemic) DL-lysine in order to obtain optically active PCA, The results show that platinized TiO₂ modified with poly (L-lactic acid) displays a higher optical purity of L-PCA as compared to normal platinized TiO₂, although the conversion was slightly lower. Platinized TiO₂ modified with poly-L-lysine on the other hand, demonstrates a much lower conversion percentage among the three samples prepared.