Graphene oxide and nanodiamond: same carboxylic groups, different complexation properties

Abstract

DFT calculations (PBE functional with the empirical correction by Grimme) were employed to explain why our attempts to coordinatively functionalize nanodiamond (ND) with tetraazamacrocyclic cations [Ni(cyclam)] 2+ and [Ni(tet b)] 2+ , and to generate paramagnetic hybrid materials in this way, failed, contrary to the successful functionalization of graphene oxide (GO) reported previously (Appl. Surf. Sci., 2016, 371, 16-27). The explanation offered is based on the comparison of binding energies for low-spin (singlet) and high-spin (triplet) complexes of model carboxylate ions GO À and ND À with the two tetraazamacrocycles. The formation energies were interpreted in terms of DDE 3À1 values, which characterize the difference in stability for the triplet and singlet complexes (negative values mean that triplet state is more stable, and positive, that singlet state is more stable). While the results obtained do not rule out completely the possibility of forming high-spin [Ni(cyclam)] 2+ carboxylate derivatives on ND, in the case of [Ni(tet b)] 2+ comparison of the DDE 3À1 values explicitly demonstrated that the formation of high-spin complex is highly unfavorable with ND À contrary to GO À model: DDE 3À1 values obtained are 13.22 and À4.64 kcal mol À1 , respectively. For comparison, similar data are presented for a series of simpler carboxylates. In addition to binding energies and DDE 3À1 values, for all the systems studied we analyzed Ni-O distances, spin density plots and HOMOÀLUMO parameters.

Carbon Nanotubes and Graphene Promote Pyrolysis of Free-Base Phthalocyanine

“…The double-numerical basis set DNP, which has a polarization d-function added on all non-H atoms and a polarization p-function added on all H atoms, was used in conjunction with PBE-D. The PBE-D/DNP level of theory in the frame of the DMol3 module was shown to be an efficient calculation methodology for description of different types of bonding between tetraazamacrocyclic (including Pcs) and many other compounds with carbon nanoclusters (fullerenes, fulleroids, graphene, graphene oxide, and nanodiamond models). ,,− Other computation settings were all-electron core treatment, Fermi orbital occupancy (no thermal smearing), and a global orbital cutoff of 4.4 Å. Full geometry optimization and single-point energy calculations were performed by using “fine” quality and convergence criteria.…”

The use of covalent reactions to improve the biomedical applications of carbon nanomaterials

“…Oxygen-containing functions including carboxyl, carbonyl, epoxy, and hydroxyl groups are usually generated by treating CNMs with mixtures of strong oxidants like HNO 3 , H 2 SO 4 , KMnO 4 [18]. As the main product of an acid treatment, carboxyl groups are mainly located on the ends of CNTs and at the edges of graphene oxide (GO) [19]. However, they can uniformly cover the surface of fullerene and NDs [20].…”