Preparation And Application Of Hollow Mesoporous Silica Nanospheres

Silica hollow spheres attracted increasing attention for their potential applicationsin loading and releasing of drugs and dyes, adsorption, optical materials and catalysisfields. Herein, silica hollow spheres with mesopores in the walls were prepared througha dual-templating approach and an ultrasonic method using mixtures of chiral cationicsurfactants and organic solvents. The morphologies and pore architectures of themesoporous silicas were characterized using scanning electron microscopy andtransmission electron microscopy. The organic solvents played important roles incontrolling the pore architectures and the morphologies of the silicas.Chiral silicas with chirality at molecular levels can be used as asymmetric catalystand enantioseparation. However, their chirality of silica surfaces is still unclear. Herein,a chirality indicator for the silica surfaces was developed based on biphenyl. It wasfound that the chirality of the silica surfaces can be transferred to the twist and stackingsof the aromatic rings which can be revealed by taking circular dichroism. It wasproposed that the other UV-active compounds with conformational chirality can be alsoused as the chirality indicators.