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| Author(s): |
Luciana Gaffo
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT) |
| Defense date: | 2002-02-22 |
| Examining board members: |
Osvaldo Novais de Oliveira Junior;
José Alberto Giacometti;
Cleber Renato Mendonça;
Ieda Lucia Viana Rosa;
Maria Elisabete Darbello Zaniquelli
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| Advisor: | Osvaldo Novais de Oliveira Junior |
| Abstract | |
This work presents the synthesis, characterization and properties of metallic phthalocyanines. For the palladium phthalocyanine (PdPc) and rhodium phthalocyanine (RhPc), only one fraction could be totally purified for work with the Langmuir-Blodgett (LB) technique. The fractions of ruthenium phthalocyanine (RuPc) could not be sufficiently purified for the fabrication of Langmuir and LB films. The film properties of rhodium phthalocyanine and ytterbium bisphthalocyanine (YbPc2), synthesized in a previous work, were investigated, which showed results depending on the experimental conditions. For YbPc2, the positioning of the pressure sensor affects the collapse pressure of the Langmuir films. This is only observed in semi-amphiphilic compounds. The surface potential of the Langmuir films depends on the compression speed, but these differences are not observed in LB films. A strong chemical interaction between stearic acid and RhPc was observed, which is unprecedented for phthalocyanines. The interaction seems less intense in LB films than in solution. The arcas per molecule in the condensed phase for the ytterbium and samarium bisphthalocyanines and rhodium phthalocyanine were 69, 60 and 75 Å2 and the collapse pressures were 52, 54 and 57 mN/m, respectively. These results show the similar characteristics of the diferente phthalocyanines. However, the surface potential was lower for RhPc, probably due to a smaller dipole component normal to the water surface. The electrochemical behavior of YbPc2 LB films depends on film thickness. In thicker films, ion diffusion is hindered, mainly in the cathodic process. LB films of YbPc2 and PdPc showed electrochromism, with changes in color upon the application of distinct potentials. In Raman spectroscopy using the 633 nm laser line, the most intense band occurs at 675 cm-1 for RhPc and YbPc2. PdPc behaves differently, with the most intense band at 1520 cm-1. Analyzing the results in the light of data in the literature, it was concluded that the dominating factor for the Raman spectra is the oxidation state of the metal. Yb and Rh metais are likely to be in the same oxidation state, differently from Pd . Comparing results from atomic force microscopy (AFM) and Raman mapping with LB films from YbPc2 mixed with stearic acid, it was observed that LB films with a larger amount of YbPc2 are more homogeneous (AU) | |