Adsorbate-dependent uptake behavior of topographically bi-functionalized ordered mesoporous silica materials

Novel behaviors such as adsorbate-dependent pore opening and functionality-controlled uptake have been accomplished by the bifunctionalized ordered mesoporous silica developed here. SBA-11 was topographically functionalized with two different functional groups by step-wise functionalization. Bulky and flexible tert-butylphenethyl (BP) groups were topographically grafted around the pore entrance and on the external surface, while small dimethyl (DM) groups were attached on the inner pore surface. The resulting bifunctionalized SBA-11 exhibited the selective malathion scavenger, which was not observed by the corresponding mono-functionalized SBA-11s. The uptake behaviors of the functionalized SBA-11s for malathion and toluene strongly suggest that the bulky and flexible BP groups are locally grafted around the pore entrance to act as a functional pore window. The interaction among the adsorbate, BP and DM groups induces a specific rearrangement of functional pore window which leads to the discriminative uptake. Therefore, the functionalized OMMs equipped with the pore window, the nanosized functional vessels, could be developed into the adsorbate-discriminating adsorbents for highly selective removal/recovery of specific organic molecules.