Abstract
A copper porphyrin and two copper phthalocyanine complexes were incorporated into a hierarchically porous carbon support formed by a sol-gel resorcinol-formaldehyde polymerization templated by F-127 block copolymer. The F127 self-organization leads to formation of mesostructure that on carbonization produces mesopores. Striking differences in catalytic activity for iodobenzene/imidazole cross coupling were observed between Alcian Blue-8gx (CuPc-8gx) (active) and copper phthalocyanine disulfonate (CuPc2S) (inactive). FTIR and EPR spectroscopy confirmed that phthalocyanine remained in the carbon after it was formed by heating to 500 °C, but that no complex survived heating to 800 °C. Electron microscopy (SEM and TEM) showed that the two dyes were differently distributed within the carbon support and found very different sizes of copper nanoparticles: 1.5 nm for CuPc-8gx and 86 nm for CuPc2S. Based on quenching of pyrene fluorescence by the two dyes it was concluded that CuPc-8gx was incorporated into F127 micelles. During polymerization the CuPc-8gx remained associated with F127 and so was incorporated into the polymer and subsequently the carbon. CuPc2S was not associated with F127 micelles, was not incorporated into the polymer and instead precipitated out during drying. This led to large CuPc2S nanoparticles, which resulted in very large copper nanoparticles with no catalytic activity.
Published Version
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