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Nanodiamonds in sugar rings: an experimental and theoretical investigation of cyclodextrin–nanodiamond inclusion complexes

2012; Royal Society of Chemistry; Volume: 10; Issue: 23 Linguagem: Inglês

10.1039/c2ob06915f

1477-0539

Jens Voskuhl, Mark P. Waller, Sateesh Bandaru, Boryslav A. Tkachenko, Carlo Fregonese, Birgit Wibbeling, Peter R. Schreiner, Bart Jan Ravoo,

High-pressure geophysics and materials

We report on the noncovalent interactions of nanodiamond carboxylic acids derived from adamantane, diamantane, and triamantane with β- and γ-cyclodextrins. The water solubility of the nanodiamonds was increased by attaching an aromatic dicarboxylic acid via peptide coupling. Isothermal titration calorimetry experiments were performed to determine the thermodynamic parameters (Ka, ΔH, ΔG and ΔS) for the host–guest inclusion. The stoichiometry of the complexes is invariably 1 : 1. It was found that Ka, ΔG and ΔH of inclusion increase for larger nanodiamonds. ΔS is generally positive, in particular for the largest nanodiamonds. β-Cyclodextrin binds all nanodiamonds, γ-cyclodextrin clearly prefers the most bulky nanodiamonds. The interaction of 9-triamantane carboxylic acid shows one of the strongest complexation constants towards γ-cyclodextrin ever reported, Ka = 5.0 × 105 M−1. In order to gain some insight into the possible structural basis of these inclusion complexes we performed density functional calculations at the B97-D3/def2-TZVPP level of theory.