Dendrimers bearing pyrene donor groups have been obtained and act as efficient light-harvesting antennae capable of transferring light energy through space from their periphery to their core. The light-harvesting ability increases with each generation due to an increase in the number of peripheral pyrenes. In order to evaluate the photovoltaic properties of the compounds, thermal evaporated thin films were produced and the voltage response in the presence of visible light was obtained. The energy transfer efficiency was found to be almost quantitative for the first and second generations. The dendrimers have the potential to become integral components of molecular photonic devices.

In the present work, it was conducted an electrochemical and kinetic study of Pd electrodeposition onto a 7 μm diameter CF (carbon fiber) ultramicroelectrode from an aqueous solution containing 1 mM of PdCl2 and 1 M NH4Cl as supporting electrolyte, a...

In this study, we carried out an electrochemical investigation of the palladium electrodeposition process at pH 5 and 8, evaluating the kinetic parameters related to its nucleation and growth processes on a Highly Oriented Pyrolytic Graphite (HOPG) electrode from a plating bath containing 1 mM of Pd and 1 M NH₄Cl. The voltammetric study allowed us to identify the potential values at which palladium can be electrodeposited, along with the adsorption and desorption processes of hydrogen absorbed on the deposited Pd. Analysis of the peak currents of the deposited Pd indicated diffusional control at both pH values. The evaluation of kinetic parameters, such as the number of active nucleation sites (N₀), the nucleation rate (A), and the rate constant of the proton reduction process (k_PR), was determined via potentiostatic studies, revealing their dependence on the applied potential to the electrode. The number of active nucleation sites predicted by the nucleation model correlated well with the number of nuclei observed via Scanning Electron Microscopy (SEM). SEM images revealed that at pH 5, the Pd clusters had an average diameter of 27 nm and a height of 39 nm, while at pH 8, the clusters had an average diameter of 12.8 nm and a height of 16.6 nm. At pH 5, homogeneous and dispersed Pd clusters were obtained, while at pH 8, agglomeration of Pd clusters was observed.

This study presents an in vitro analysis of the bactericidal and cytotoxic properties of hybrid films containing nickel oxide (NiO) and nickel ferrite (NiFe₂O₄) nanoparticles embedded in polypropylene (PP). The solvent casting method was used to synthesize films of PP, PP@NiO, and PP@NiFe₂O₄, which were characterized by different spectroscopic and microscopic techniques. The X-ray diffraction (XRD) patterns confirmed that the small crystallite sizes of NiO and NiFe₂O₄ NPs were maintained even after they were incorporated into the PP matrix. From the Raman scattering spectroscopy data, it was evident that there was a significant interaction between the NPs and the PP matrix. Additionally, the Scanning Electron Microscopy (SEM) analysis revealed a homogeneous dispersion of NiO and NiFe₂O₄ NPs throughout the PP matrix. The incorporation of the NPs was observed to alter the surface roughness of the films; this behavior was studied by atomic force microscopy (AFM). The antibacterial properties of all films were evaluated against Pseudomonas aeruginosa (ATCC^®: 43636™) and Staphylococcus aureus (ATCC^®: 23235™), two opportunistic and nosocomial pathogens. The PP@NiO and PP@ NiFe₂O₄ films showed over 90% bacterial growth inhibition for both strains. Additionally, the effects of the films on human skin cells, such as epidermal keratinocytes and dermal fibroblasts, were evaluated for cytotoxicity. The PP, PP@NiO, and PP@NiFe₂O₄ films were nontoxic to human keratinocytes. Furthermore, compared to the PP film, improved biocompatibility of the PP@NiFe₂O₄ film with human fibroblasts was observed. The methodology utilized in this study allows for the production of hybrid films that can inhibit the growth of Gram-positive bacteria, such as S. aureus, and Gram-negative bacteria, such as P. aeruginosa. These films have potential as coating materials to prevent bacterial proliferation on surfaces.