Conjugated Gold–Porphyrin Monolayers Assembled on Inorganic Surfaces

Abstract

Gold nanoparticles show important properties owing to their electronic structures. A limitation of some gold nanoparticles is that they either show surface plasmons or luminescence. The increase in size of the gold nanoparticles, and the appearance of the surface plasmons may result in the disappearance of luminescence. The aim of our study is the nanoscale assembly of Au nanoparticles on a monolayer of porphyrin molecules anchored to functionalized inorganic surfaces. This functional architecture not only exhibits a strong surface plasmon due to the gold nanoparticles, but also a strong luminescence signal from the porphyrin molecules. Finally we observed a long-range order in the Au nanoparticles conjugated to the porphyrin monolayer.

High-Performing Au-Ag Bimetallic Catalysts Supported on Macro-Mesoporous CeO2 for Preferential Oxidation of CO in H2-Rich Gases

“…Figure 6a shows the XPS spectrum of the AuAg/CeO 2 sample in the Au 4f binding energy region. The Au 4f 7/2,5/2 spin-orbit components lie at 83.6 and 87.3 eV (3.7 eV spin-orbit coupling), respectively, pointing to the attendance of the Au 0 state, whose 4f 7/2 levels are reported to be at 84.0 eV [56][57][58][59]. These binding energies match with those measured for the Au/CeO 2 sample ( Figure S3a).…”

Covalently Conjugated Gold–Porphyrin Nanostructures

“…In this study, we preliminary reduced Au 3+ with sodium citrate to obtain Au NPs and synthesized a new porphyrin to fabricate assemblies comprising of Au NPs covalently anchored to each other by porphyrin molecules (Scheme 2) [46][47][48][49][50][51][52].…”

“…The study of the electronic structure of the Au NPs-porphyrin nanostructures is fundamental to investigate the Au-porphyrin electron interactions, which are the basis of the coupling of the plasmon Au resonance with the porphyrin emission, and XPS represents the most suited tool to accomplish this task [34,[52][53][54][55]. Figure 4 shows the XP spectra of pure Au NPs and Au NPs-porphyrin nanostructures, in the Au 4f binding energy region.…”

“…The Au surface plasmon resonance (SPR) peak lies at 520.6 nm (Abs = 1.5). By using literature data for the related extinction coefficient (ε = 7.6 × 10 6 M −1 cm −1 [ 52 ]), we obtained a 1.97 × 10 −7 M concentration value for this Au NPs solution. Figure 8 shows the absorbance spectra of 100 µL of this Au NPs aqueous solution, diluted with 2 mL of CH 3 OH (V tot = 2.1 mL), and those upon the successive addition of aliquots of a 2.07 × 10 −5 M porphyrin CH 3 OH solution, up to a final added porphyrin volume of 900 µL, corresponding to 1.86 × 10 −8 mol, (final total volume 3 mL).…”

“…In order to synthesize the Au NPs-porphyrin nanostructures, we added aliquots of a 2.07 × 10 −5 M porphyrin CH 3 OH solution (final added volume 900 µL, in 400 min, corresponding to 1.86 × 10 −8 mol) to 100 µL of an Au NPs aqueous 1.97 × 10 −7 M solution, diluted with 2 mL of CH 3 OH (final total volume 3 mL) [52]. The synthetic reaction pathway is represented in Scheme 2.…”