Covalent and Non-covalent Conjugation of Few-Layered Graphene Oxide and Ruthenium(II) Complex Hybrids and Their Energy Transfer Modulation via Enzymatic Hydrolysis

Pyrene-containing ruthenium(II) tris-bipyridine complexes have been prepared. These complexes have been non-covalently attached onto the few-layered graphene oxide (GO) sheets through their high binding affinity for flat π-surfaces. Alternatively, the reduced graphene oxide (rGO) sheets have also been covalently functionalized with the ruthenium(II) tris-bipyridine complex. The prepared conjugates have been characterized by transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy, thermogravimetric analysis (TGA), and UV-visible absorption spectroscopy. The energy transfer properties of the resulted conjugates between the graphene and transition metal complexes have been studied via esterase hydrolysis. The energy transfer efficiencies were found to vary with the separation between the donor and the acceptor units.