Fabrication of pore window in ordered mesoporous silica by spatial control of functional groups

Great difficulty has been found in controlling the spatial distribution of functional organic groups grafted onto ordered mesoporous silicas even though it plays a decisive role in many applications. Topographical multifunctionalization of rod-shaped MCM41 crystals has been accomplished in this study through selective surface fluorination and subsequent step-wise grafting of organic groups, leading to fabrication of a functional pore window on pore entrance surface. Distinctive fabrication of functional organic window around pore entrance was visualized by the distribution of window-complexed Pb cations in a narrow band within a distance of about 10-60. nm from both vertical crystal edges, pore entrances. Its unique function was clearly illustrated by interfacial property of the MCM41 crystals with both a guest molecule and a substrate surface. In particular, its lock-and-key function was successfully demonstrated by pH-dependent locking and unlocking of pore opening. Therefore, this study would contribite substantially to selective and precise manipulation of surface functionality in ordered mesoporous silica materials for tailor-making of diverse delivery vectors and nanoreactors.