Functionalization of Deuterium- and Hydrogen-Terminated Diamond Particles with Mono- and Multilayers using Di-tert-Amyl Peroxide and Their Use in Solid Phase Extraction

In spite of an earlier report to the contrary and a different attempt that appears to have been unsuccessful, here we show an improved method that allows functionalization of hydrogen- and deuterium-terminated diamond with a dialkyl peroxide. In particular, hydrogen-/deuterium-terminated diamond particles were treated with neat di-tert-amyl peroxide (DTAP, C2H5C(CH3)(2)OOC-(CH3)(2)C2H5) at elevated temperature. Surface changes were followed by X-ray photoclectron spectroscopy (XPS), diffuse reflectance Fourier transform infrared spectroscopy (DRIFT), and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). After these reactions, the oxygen signal in the XPS spectra increased, the deuterium peak in the negative ToF-SIMS spectra decreased, and DRIFT showed C-H stretches, which were not previously present and which were similar to those of the precursor. In the C-H stretching region, the IR spectrum of adsorbed di-tert-amyl peroxide shows features that are red-shifted with respect to the IR spectrum of the precursor molecule. These trends are supported by density functional theory (DFT) calculations. These data are consistent with the chemisorption of fragments of di-tert-amyl peroxide primarily through ether linkages. The threshold for this reaction was determined by DRIFT to be ca. 95 degrees C. Multilayers of DTAP could be prepared by repeated exposure of the substrate to this reagent. Functionalized diamond particles were used in solid phase extraction.