π-Interactions as a tool for an easy deposition of meso-tetraferrocenylporphyrin on surfaces

Abstract

A bottom-up approach was employed to prepare novel Self-Assembled Monolayers (SAMs) in which a naphthyl moiety acted as a ''p-binder'' for unfunctionalised meso-tetraferrocenylporphyrin (H 2 TFcP).Four naphthalene derivatives with an appropriate functional group were synthesized and SAMs were prepared both on gold and ITO surfaces. Mixed H 2 TFcP-naphthalene films were thoroughly characterized using UV-Vis, XPS and electrochemical techniques. In particular, angle-dependent XPS experiments revealed an almost perpendicular orientation of the porphyrin on surfaces, suggesting that an intercalation occurred among naphthalene units. A large amount of porphyrin was deposited on both the surfaces (in the order of 10 À10 mol  cm À2), comparable to that afforded by more conventional covalent linkages. However, significant differences in homogeneity between SAMs on gold and ITO resulted in a diverse electrochemical behaviour. The electrochemical activity of the oxidised porphyrin was restored by prolonged exposure of the modified gold electrode (tens of seconds) to a negative potential, whereas no response was detected after the same treatment on ITO. This novel approach provides a general and versatile strategy to bind meso-substituted porphyrins on a pre-formed monolayer without the necessity for further functionalisations.

Regulation of the Interfacial Effects of Thin Polystyrene Films by Changing the Aromatic Group Structure on Substrate Surfaces

“…However, the naphthyl is tethered onto the substrate by covalent bonding and cannot be randomly orientated. Therefore, the naphthyl group is still well perpendicular to the interface, similar to the reported structure of the naphthyl-modified substrates . Moreover, the SFG spectra are related to the orientation and surface coverage of the functional groups.…”

“…Therefore, the naphthyl group is still well perpendicular to the interface, similar to the reported structure of the naphthyl-modified substrates. 47 Moreover, the SFG spectra are related to the orientation and surface coverage of the functional groups. The intensity of the SFG spectra is proportional to the square of the group density (N), whereas all of the groups have the same orientation as shown in eq 1.…”

Amphiphilic Porphyrin Aggregates: A DFT Investigation

“…Porphyrin assemblies are widespread in nature, where they are engaged in essential processes, such as efficient transport or storage of oxygen through the blood plasma or electron transfer in photosynthesis. Inspired by the diverse self-assembly motifs in nature, researchers have constructed and applied synthetic porphyrin systems in a variety of applicative fields, ranging from photocatalysis to sensors and material science [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Indeed, the choice of porphyrin-based building blocks to organize supramolecular systems is extremely advantageous for several reasons: (i) their chemical versatility supported by well-established synthetic methodologies; (ii) their distinctive optical features; and (iii) their invaluable photophysical and photochemical properties that enhance the assembled materials, with obvious impacts on the performance in technological applications.…”

Electrochemical and Surface Characterization of Dense Monolayers Grafted on ITO and Si/SiO2 Surfaces via Tetra(tert‐Butoxy)Tin Linker

“…In particular, indium tin oxide (ITO) is widely employed for technological and scientific applications as it is a valuable low band gap semiconductor which is also transparent in a rather wide spectral region, that extends from UV to Near‐Infrared (NIR), and hence it has proved to be a very interesting material for various applications such as in sensing and optoeletronics, where it is the material of choice for photovoltaic devices and light emitting diodes . A large part of the studies done on the functionalization of ITO or, more generally, oxide semiconductors, has discussed different strategies based on wet‐chemical processes and on the use of a variety of reactants spanning from alkoxy‐ and chlorosilanes , carboxylic acids , phosphonic acids , as well as organic molecules that can form polymeric films . Furthermore, procedure involving electrochemically generated radicals have been explored as viable methods to graft new functionalities at the ITO surface, borrowing a methodology for the deposition of thin films on metal, semiconductor and carbon based surfaces .…”