Novel metal-free and metallophthalocyanines were synthesized by cyclotetramerization of 3-(2,3-dihydro-1H-inden-5-yloxy)phthalonitrile and characterized. The redox properties of these compounds were investigated by cyclic voltammetry, square-wave voltammetry, controlled-potential coulometry and in situ spectroelectrochemistry in dimethylsulfoxide and dichloromethane. The compounds displayed metal and/or phthalocyanine ring-based reduction and oxidation processes. The color changes associated with these redox processes and electrogenerated anionic and cationic redox species were recorded with in situ electrocolorimetric measurements. The electrocatalytic performances of the compounds toward oxygen reduction reaction having vital importance for fuel cell applications were determined by hydrodynamic rotating disk and bipotentiostatic rotating ring-disk voltammetry measurements. The Vulcan XC-72/Nf/FePc modified glassy carbon electrode showed much higher catalytic performance toward oxygen reduction than those of the other modified ones. Furthermore, the field dependence of dielectric response and the conductivity of the samples were measured as a function of frequency and temperature. Dielectric relaxation behaviors of the phthalocyanines were also investigated. The ITO/ZnPc/Au sample showed the highest value of ɛ′(ω) as compared to the other samples. The analysis of the real and imaginary parts of the dielectric permittivity with frequency was carried out assuming a distribution of relaxation times as well as the scaling behavior of the dielectric loss spectra.
The synthesis of novel alpha tetra, beta tetra and beta octa 4-(4-methoxyphenyl)-8-methyl-coumarin-7-oxy, and beta octa 4-chloro-5-(4-(4-methoxyphenyl)-8-methylcoumarin-7-oxy) substituted iron(II) phthalocyanines has been achieved by the reaction of the corresponding phthalonitriles with iron(II) acetate. The compounds were characterized by elemental analysis, FT-IR, UV-vis, and MALDI-TOF mass spectrometry. The reduction and oxidation properties of the compounds were identified by voltammetric and in situ spectroelectrochemical measurements. The gas sensing behavior of the spin coated films of the differently substituted iron(II) complexes towards CO2, CO and SO2 was investigated at various temperatures between 300 K and 500 K. While exposure to SO2 had no considerable influence on the sensor current, the presence of CO and CO2 gases led to a large increase in sensor currents. The effect of relative humidity on the CO and CO2 sensing capability of the spin coated films was also studied. The results showed that the presence of water vapor, acting as an interference gas, causes a decrease in the CO2 sensitivity, but an increase in the CO sensitivity of the sensors. The experimental adsorption data were analyzed using the Elovich kinetic model. Linear regression analysis results show that the Elovich equation provides the best correlation for the CO2 and CO adsorption processes under humid conditions. However, the experimental data deviated considerably from the theoretical model under a dry atmosphere.
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