The existence of carboxylic groups on the surface of graphene oxide (GO) and nanodiamond (ND) offers rich possibilities for the covalent, ionic and coordination functionalization of these important classes of carbon nanomaterials, and thus for broadening the spectrum of their useful properties and potential applications. For example, the attachment of tetraazamacrocyclic complexes to GO is extensively studied with an emphasis on hybrid nanomaterials for the uses in organic photovoltaics, spin electronics and electrocatalysis. In the present work, we explored the possibility of coordination functionalization of GO and ND with Ni(II) complexes of 1,4,8,11-tetraazacyclotetradecane (cyclam) and rac-5,7,7,12,14,14-hexamethyl-1,4,8,1l-tetraazacyclotetradecane (tet b). Both [Ni(cyclam)]2+ and [Ni(tet b)]2+ exist in diamagnetic square-planar tetracoordinated state in neutral and acidic media, however, are known to adopt a folded hexacoordinated conformation upon coordination with carboxylate ions in basic media (thus becoming paramagnetic complexes). It is the latter property which was employed by us for the attachment of [Ni(cyclam)]2+ and [Ni(tet b)]2+ to COOH groups of GO and ND. The nanohybrids obtained were characterized by using electron paramagnetic resonance, Fourier-transform infrared, Raman and X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron, transmission electron and atomic force microscopy. Additional information about structure and properties of the macrocycle‒GO nanohybrids was obtained from density functional theory calculations (DMol3 numerical-based DFT module, Materials Studio 6.0 package from Accelrys Inc., PBE GGA functional with Grimme dispersion correction, in conjunction with the double numerical basis set DNP). Financial support from UNAM (grants DGAPA-IN100112 and IN101313) and CONACyT (grant 127299) is greatly appreciated. N. A.-C. and L. V. H.-H. are indebted to the Doctorate Program in Chemical Sciences of UNAM and CONACyT for a Ph. D. fellowship.

Coordination functionalization of graphene oxide and nanodiamond with nickel(II) tetraazamacrocyclic complexes

249th National Meeting (2015)

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