Sandwich structures were fabricated by a vacuum deposition method using MPc (M = Cu, Zn), with a Tetrathiafulvalene (TTF) derivative, and Indium Tin Oxide (ITO) and aluminum electrodes. The structure and morphology of the deposited films were studied by IR spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The absorption spectra of TTF derivative-MPc (M = Cu, Zn) thin films deposited at room temperature were recorded in the spectral range 200–1000 nm. The optical band gap of the thin films was determined from the (αhν)^1/2 vs. hν plot. The direct-current (DC) electrical properties of the glass/ITO/TTF_deriv-MPc (M = Cu, Zn)/Al structures were also investigated. Changes in conductivity of the derivative-TTF-enriched Pc compounds suggest the formation of alternative paths for carrier conduction. At low voltages, forward current density obeys an ohmic I-V relationship; at higher voltages, conduction is mostly due to a space-charge-limited conduction (SCLC) mechanism.

The structure formed by cobalt phthalocyanine (CoPc) and cobalt octaethylporphyrin (CoOEP) with electron-acceptor tetracyano-π-quinodimethane (TCNQ), was studied by Density Functional Theory (DFT) methods. According to theoretical calculations, both cobalt systems can establish dispersion forces related to TCNQ and also in both cases the link between them is built by means of hydrogen bonds. Based on the results of these DFT calculations, we developed experimental work: the organic semiconductors were doped, and the thermal evaporation technique was used to prepare semiconductor thin films of such compounds. The structure of the films was studied by FTIR and Raman spectroscopy. The optical properties of the CoPc-TCNQ and CoOEP-TCNQ films were investigated by means of UV-Vis measurements. The results obtained were used to estimate the type of transitions and the optical bandgap. The results were compared to the previously calculated theoretical bandgap. The CoOEP-TCNQ film presented the smallest theoretical and experimental bandgap. Finally, the electrical properties of the organic semiconductors were evaluated from a PET (polyethylene terephthalate)/indium tin oxide (ITO)/cobalt macrocycle-TCNQ/silver (Ag) device we prepared. The CoOEP-TCNQ-based device showed an ohmic behavior. The device manufactured from CoPc-TCNQ also showed an ohmic behavior at low voltages, but significantly changed to SCLC (space-charge limited conductivity) at high voltage values.

Transition metal macrocyclic complexes have acquired relevance as electrocatalysts to perform oxygen electroreduction in acid media as an alternative to platinum. This work presents two macrocyclic complexes using cyclam as ligand, which has a much simpler molecular structure (smaller size, no π-electrons, etc.) than the well studied porphyrins and phthalocyanines as transition metal complexes. Such compounds are usually subjected to thermal treatments at relatively high temperatures (800–900 °C) which result in ligand decomposition, leaving the so-called MN_x active sites. In contrast, the complexes reported in this work are efficient electrocatalysts for the oxygen reduction reaction (ORR) in their original molecular structure, with no thermal treatments of any kind applied. The electrocatalytic activity of the Rh(III)-cyclam and Ru(III)-cyclam complexes during the ORR in the absence and presence of methanol (2 mol L⁻¹) was evaluated by voltammetry techniques. The kinetic parameters of the novel materials for the reaction were determined. The exchange current density (j₀) values, directly related to the charge transfer velocity, are of the same order as or higher than those of platinum/Vulcan® nanoparticles. In addition, they are practically unaffected by methanol, therefore, becoming interesting candidates to be evaluated as cathodes in polymer electrolyte membrane and direct methanol fuel cells.