A model has been developed for diffusion controlled electrodeposition of metallic particles at the interface between two immiscible electrolyte solutions. A rate law was derived for the case where no preferential nucleation sites are present. Palladium particles were deposited at the water 1,2-dichloroethane interface by reduction of aqueous ammonium palladate using butylferrocene in the organic phase as electron donor. Experimental results were in good agreement with the theoretical model derived. The potential dependence of the nucleation rate was found to follow a classical exponential law.

Photoinduced processes in phthalocyanine-functionalized gold nanoparticles (Pc-AuNPs) have been investigated by spectroscopic measurements. The metal-free phthalocyanines used have two linkers with thioacetate groups for bonding to the gold nanoparticle surface, and the attachment was achieved using a ligand exchange reaction. The absorption spectrum of the Pc-AuNPs shows a broadening of the phthalocyanine Q-band absorption, probably due to a tight packing of the phthalocyanines on the gold nanoparticle surface. For the attached phthalocyanines, fluorescence is strongly quenched, and the fluorescence lifetimes determined by time-correlated single photon counting (TCSPC) are strongly reduced. The quenching mechanisms were studied in detail with time-resolved absorption (pump−probe) measurements. A selective excitation of the gold cores in the pump−probe experiment results in an energy transfer from the gold nanoparticles to the attached phthalocyanines in ∼2.4 ps. Photoexcitation of mainly the phthalocyanines in the functionalized nanoparticles leads to an electron transfer to the gold core in ∼3.0 ps. The recombination of charges in the Pc-AuNP takes place on a picosecond time scale. In addition, there is evidence of energy transfer from the photoexcited phthalocyanines to the gold nanoparticles.

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Photoinduced vectorial electron transfer in a molecularly organized porphyrin-fullerene (PF) dyad film is enhanced by the interlayer charge transfer from the porphyrin moiety of the dyad to an octanethiol protected (dcore approximately 2 nm) gold nanoparticle (AuNP) film. By using the time-resolved Maxwell displacement charge (TRMDC) method, the charge separation distance was found to increase by 5 times in a multilayer film structure where the gold nanoparticles face the porphyrin moiety of the dyad, that is, AuNP|PF, compared to the case of the PF layer alone. Films were assembled by the Langmuir-Blodgett (LB) method using octadecylamine (ODA) as the matrix compound. Atomic force microscopy (AFM) images of the monolayers revealed that AuNPs are arranged into continuous, islandlike structures and PF dyads form clusters. The porphyrin reference layer was assembled with the AuNP layer to gain insight on the interaction mechanism between porphyrin and gold nanoparticles. Interlayer electron transfer was also observed between the AuNPs and porphyrin reference, but the efficiency is lower than that in the AuNP|PF film. Fluorescence emission of the reference porphyrin is slightly quenched, and fluorescence decay becomes faster in the presence of AuNPs. The proposed mechanism for the electron transfer in the AuNP|PF film is thus the primary electron transfer from the porphyrin to the fullerene followed by a secondary hole transfer from the porphyrin to the AuNPs, resulting in an increased charge separation distance and enhanced photovoltage.

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