Sunlight-initiated self-assembly of cyclodextrin networks

We demonstrate sunlight initiated self-assembly of three-dimensional networks of β-cyclodextrin using simulated AM1.5 sunlight conditions. These all-organic networks display a highly porous hierarchical structure of interconnected fibers similar to the TiO2–Cyclodextrin hybrid networks prepared previously. These results clearly identify cyclodextrin as the structure-directing agent providing important new insights into the network formation mechanism. Vibrational and thermal analysis suggest that the cyclodextrin molecules are dehydrated and their cone structure is broken to form a more stable molecular unit. From this data we introduce a formation model based on titania photocatalyzed reaction of cyclodextrin molecules. Subsequently, hydrophobic and surface tension forces drive the self-assembly into large networks of interconnected fibers resembling marine sponges. These results are significant because they demonstrate that cyclodextrin can be used to template the self-assembly of hierarchical networks of both organic and inorganic materials. More broadly, this technique represents a simple and eco-effective route to grow biomimetic structures directly using sunlight.