Template-stereocontrolled [2 + 2] photoreactions directed by surface recognition on hydrophilic functionalized carbon materials

Abstract

Supramolecular assistance of the regioselective synthesis of single dimers from [2 + 2] photoreactions surface-directed by multivalent H-bonding exo-templates based on hydrophilic carbon materials (HCMs) is highlighted for the first time. Supramolecular photochemistry of stilbenes assisted by either functionalized carbon nanotubes or sub-microspheres afforded a single rtct-isomer after two consecutive steps in solution (UV-irradiation and hydrothermal isomerization). Carbon spheres display the ability to mediate the dimerization of 4-cinammic acid derivatives with moderate to quantitative yields. This result is obtained either in solution or via mechanochemical grinding assistance of carbon sphere/cinnamic derivative assemblies. The structure-templating features of such nanomaterials are discussed as a function of surface recognition processes due to the presence of -COOH and -OH groups on the surface and the effective carbon template:substrate ratio.