Nanodiamond-Palladium Core-Shell Organohybrid Synthesis: A Mild Vapor-Phase Procedure Enabling Nanolayering Metal onto Functionalized sp(3)-Carbon

A novel approach for the bottom-up construction of hybrid organic-inorganic nanocomposites with an intimate arrangement between sp(3)-carbon 3D molecular-size nanodiamonds (diamondoids) and a coated palladium surface as nanolayer is reported. The construction process is conducted stepwisely from the gas phase, using first controlled vapor-phase self-assembly of tailor-made functionalized diamantane derivatives, followed by low-temperature (45 degrees C) chemical vapor deposition of an organometallic complex in a reducing H-2 atmosphere over the self-assembled diamondoid scaffold. The use of self-assemblies of primary diamantane phosphine and phosphine oxide, which are produced with high structural uniformity and reproducibility, yields new hybrid diamondoid-palladium materials incorporating Pd-O-PH-diamantane bonding motifs. Additional investigations provide evidence for a very challenging issue in the intimate construction of sp(3)-C/metal scaffolds. Scanning electron microscopy and transmission electron microscopy microscopies combined with X-ray photoelectron spectroscopy surface analysis and EDX bulk analysis confirm the formation of diamondoid-palladium organohybrids with unique surface layering. The vapor phase-controlled mild synthetic process allows excellent control over nanocomposite formation and morphology from molecular-level modifications. As such, this bottom-up composite building process bridges scales from the molecular (functionalized diamondoids) over nanoscopic (self-assemblies) to microscopic regime (hybrids), in the challenging association of transition metals with an electronically saturated sp(3)-carbon organic host material.