Binding of dinuclear ruthenium complexes, SWNTs and nanoparticles for hybrid nanocomposite materials

Integration of nanomaterials into composite systems is the next evolutionary step in nanoscale science. Until recently nanocomposites are formed by embedding nanomaterial components into matrices, through chemical bonding or with various wrapping agents. We seek to show that through directed self assembly nanomaterials can be coupled with photosensitizing ruthenium complexes while avoiding chemical augmentation and insulating effects from polymer, surfactant or DNA wrapping. We have synthesized dinuclear ruthenium complexes (dimers) possessing rigid conjugated π-electron systems that form a nanoscale pocket. The pocket is dimensionally suited to interact strongly with nanomaterials forming an architecture that could facilitate photon collection and charge transfer across the interaction. This study explores the binding interaction of our ruthenium dimers with SWNTs. The binding strength varies relative to the magnitude of formal charge which trends with DFT simulations that predict SWNT dimer interactions. SWNT surface saturation by ruthenium dimers can be observed using UV-visible spectroscopy and characterized with adsorption isotherms. We also explore a new technique to measure nanomaterial interactions, isothermal titration calorimetry (ITC). We show that ITC can be used to directly measure the binding enthalpy of nano material surface interactions in solution. © 2011 Materials Research Society.