Supramolecular host-guest and fluorescence studies on Ni-Salphen complex as a binding unit on edge oxidised graphene oxide grafted nanomaterial

The synthesis, characterisation, and crystallographic analysis of a novel -OH functionalised Ni-Salphen complex and its hybrid nanomaterial counterparts in the form of the molecule covalently bonded to Edge-Oxidised Graphene Oxide are described. Spectrophotometric titrations of the complex and of the nanomaterial performed against different pyridine-based guests showed a constant stoichiometry of association but different trends in association constants upon grafting. These changes could be ascribed to differences in the supramolecular environment at the binding site upon grafting, which may find cooperativity thanks to additional interactions arising from the graphene component. The spectrofluorimetric emission profile was explored before and upon association to find that emission intensity was affected in a different manner depending on whether the complex was used as a free molecule or in the hybrid nanomaterial, while it also depended on the size and flexibility of the guest used.