Friday 31 October 2014, 1.00PM to 2.00pm
Speaker(s): Dr Simon Humphrey
Noble Metal Nanoparticles and Phosphine Coordination Materials for Heterogeneous Catalysis, Sequestration and Sensing
A new microwave-assisted method for the synthesis of noble metal nanoparticles affords improved control over particle morphology and resulting catalytic reactivity. Microwave heating allows for facile removal of organic polymer capping agents and functionalization with secondary capping agents that can induce superior surface chemistry. Alloy nanoparticles based on combinations of metals that are immiscible in the bulk can also be prepared. Synergistic electronic and ensemble effects in the alloys dramatically improve the overall catalytic performance. For example, RhAg nanoparticles are significantly more highly active in alkene hydrogenation than pure Rh nanoparticles, even though Ag is catalytically inactive and Rh is diluted in the alloy nanostructures.
Water-soluble phosphines of the type that are ubiquitous in biphasic organometallic catalysis are ideal precursors for the construction of hybrid organic-inorganic porous polymer materials. The so-called PCMs (Phosphine Coordination Materials) can subsequently be chemically modified in a large variety of ways to decorate the pores with chemical moieties that induce unique guest selectivity behavior, such as alkenealkane separation and small molecule sensing and discrimination. Bis(phosphines) coordinationcomplexes tailored with ancillary polymerizable groups can be used to construct heterogeneous catalyst materials with defined, single-site active species.