Ligand Initiated Self-Assembly of Pt and Ir Nanoparticles about Ru(II) Diimines in Room Temperature Fluid Solution

Abstract

The addition of Pt or Ir nanoparticles (np’s) capped with poly(vinylpyrrolidone), designated M(PVP)n, to aqueous–ethanol solutions of (bpy)2Ruppz2+, bis(2,2′-bipyridine)(4,7-phenanthrolino-5:6,5′6′-pyrazine)ruthenium(II), and (bpy)2Rudpp2+, bis(2,2′-bipyridine)(2,3-bis(2-pyridyl)pyrazine)ruthenium(II), leads to the spontaneous aggregation of the nanoparticles about the complex. A comparison of the aggregation about different Ru(II) diimines indicates aggregation initiates at the heteroleptic ligand. Although initiating at the ppz ligand, continued aggregation of the np’s about the complex dilutes the specificity of the initial interaction, leading to larger aggregates of differing shape. TEM analyses of the aggregates indicate the volume occupied by the individual np’s is a small fraction of the total volume of the aggregate, suggesting a somewhat open structure interlaced with the solvent. Correlating TEM analyses of the aggregation with the electronic spectra of the solutions reveals a new absorption as...