The physical and chemical properties of nanomaterials are governed in part by size, shape and surface morphology. For example, metallic nanoclusters of sizes ranging from 1-10 nm have vastly different properties than their bulk forms. Few, if any, studies have reported about the characteristics of nanomaterials composed entirely of metal complexes because limited preparative methods have hindered production. Described in this disclosure is a process for the formation of nanoparticles of neutral metal complexes. The process uses supercritical carbon dioxide as a cosolvent to precipate nanosized particles of the desired complexes. Spectroscopic and analytical methods were used to support the assignment that the nanoparticles are composed of metal complexes. Microscopy reveals that there is a correlation between the structures of the molecular precursors and the final morphology of the nanoparticles. For example, planar complexes result in rod-like particles with average diameter and length of 85 nm and 700 nm, respectively. Complexes with non-planar molecular structures produce nanoparticles with varied structures; a six-coordinate complex yields spherical nanoparticles with average diameters of 50 nm. Our finding that one controlling variable is the molecular structure of the precursor compounds could lead to new and possibly enabling methods for manipulating the structures of molecule-based nanoparticles. This bottom-up approach would then yield particles whose structures can be varied to enhance applications in absorption, catalysis, and coating technology.

File Number: KUCR # 2005 FY 35 

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