The synthesis, light-harvesting, and photocatalysis of naphthylporphyrin-functionalized platinum nanocomposites

A tetraphenylporphyrin bearing four naphthalene donor moieties (5,10,15,20-tetrakis(4-(naphthalen-1-ylmethoxy)phenyl)porphyrin were synthesized and characterized using H-1 NMR, FTIR, UV-vis, FL, TEM, and XRD. Substituting the naphthalene groups onto the porphyrin ring led the molecule to absorb over a broader range (200-700 nm) and to undergo efficient intramolecular energy transfer from the naphthalene to the porphyrin ring. MR, XRD and TEM analyses indicated that within a functionalized platinum nanocomposite comprising the porphyrin, the photoreceptive dye forms a shell containing a nanosize Pt core (similar to 2.8 nm). The photocatalytic activity of the Pt nanocomposite towards water reduction to hydrogen was >twice that of a Pt-naphthalene-free porphyrin system. The turnover numbers (TONPt and TONdye) and quantum yields of hydrogen were 72, 7200 and 3.0%, respectively, calculated on the basis of the total amount of H-2 evolved after 12 h irradiation. (C) 2009 Elsevier Ltd. All rights reserved.