Synthesis of pegylated metal phthalocyanines, incorporation in hierarchically porous carbon monoliths and evaluation as heterogeneous catalysts

Abstract

Copper and nickel phthalocyanines incorporating four polyethylene glycol (PEG) chains were synthesized for PEG of 200, 400 and 600 molecular weights. The functionalized phthalocyanines were incorporated into a resorcinol-formaldehyde polymer which was converted to a hierarchically porous macroporous-mesoporous carbon by pyrolysis. The pyrolysis released metal atoms from the phthalocyanines which agglomerated to give metal nanoparticles. Particle sizes were determined by SEM and TEM. Phthalocyanines with PEG of 400 molecular weight gave the smallest nanoparticles, in the 3–10 nm range. Catalytic activity for cyclohexene oxidation (for copper phthalocyanines) and p-nitrophenol reduction (for nickel phthalocyanines) were studied, and found not to correlate well with nanoparticle size, likely reflecting differences in accessibility of the nanoparticles on the carbon surface vs. nanoparticles formed within the carbon matrix.