Supramolecular nanomaterials with photocatalytic activity obtained via self-assembly of a fluorinated porphyrin derivative

Abstract

Porphyrin aggregates formed via self-assembly have shown promising photocatalytic activity due to the combination of their optical and morphological properties. The structural and physical properties of porphyrin affect its self-assembly and the properties of the resulting aggregates. The hydrophobicity/hydrophilicity of the porphyrins in solvent mixtures, which affect self-assembly, can be altered by the introduction of fluorine groups. In this work, we report the synthesis of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TPFPP). The differing solubilities of TPFPP in organic and aqueous solutions were exploited to promote the self-assembly of monomeric TPFPP in THF/H sub(2) O solvent mixtures. The effect of the H sub(2) O fraction on the assembly process and resulting morphologies was probed using UV-vis spectroscopy, photoluminescence spectroscopy, and scanning electron microscopy (SEM). It was observed that well-defined TPFPP microrods with a diameter of 1-3 micro m and length of 20-100 micro m as well as octahedral crystals 30 micro m in size were produced with H sub(2) O fractions of 70 and 80 percent, respectively. These TPFPP aggregates with controlled morphologies exhibited high photocatalytic activity, evident in photocatalytic degradation studies with rhodamine B (RhB) which degraded under visible light irradiation with rate constants of 3.76 x 10 sup(-3) (with microrods) and 2.93 x 10 sup(-3) min sup(-1) (with octahedral crystals). A possible mechanism for the photocatalytic activity of the TPFPP aggregates for RhB degradation was proposed.