Photochemically Triggered Assembly of Composite Nanomaterials through the Photodimerization of Adsorbed Anthracene Derivatives

Gold nanoparticles were assembled into three-dimensional aggregates in colloidal dispersions and were attached to ZrO2 surfaces through photoinduced [4 + 4] cycloaddition reactions between adsorbed anthracene derivatives. Composite materials were characterized by ultraviolet/visible/near-IR spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Aggregates of gold nanoparticles with diameters of several micrometers were Formed within 45 min of illumination at 355 nm and 130 mW/cm(2). Aggregation was attributed primarily to interfacial photodimerization between anthryl groups on different gold nanoparticles. although intramonolayer photodimerization reactions may also have occurred. 9-Anthracenethiolate-capped gold nanoparticles were attached to 2-anthroate-functionalized ZrO2 surfaces upon excitation of anthryl pi-pi* transitions. ToF-SIMS data and the results of control experiments Suggested that the materials assembly mechanism involved [4 + 4] cycloaddition reactions between adsorbed anthryl groups on gold and ZrO2. Patterned arrays of nanoparticles with similar to 100-mu m features were deposited onto surfaces, The use Of interfacial photodimerization reactions to trigger materials assembly processes may represent an attractive materials fabrication strategy, in which photopatternings, (top-down) and nanoparticle-adsorption (bottom-up) processes proceed via a single photoinduced reaction.