Photoconductive novel mesomorphic oxotitanium phthalocyanines |
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Authors: | Dilek Dündar Hatice Can Devrim Atilla Ayşe Gül Gürek Zafer Ziya Öztürk Vefa Ahsen |
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Institution: | 1. Gebze Institute of Technology, Science Faculty, Department of Physics, P.O. Box 141, Gebze-Kocaeli 41400, Turkey;2. TÜB?TAK-Marmara Research Center, Materials Institute, Gebze-Kocaeli 41470, Turkey;3. Gebze Institute of Technology, Science Faculty, Department of Chemistry, P.O. Box 141, Gebze-Kocaeli 41400, Turkey |
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Abstract: | The synthesis and photoconductivity properties of the alkylthia and triethyleneoxysulfonyl substituted oxotitanium(IV) phthalocyanines (1a and 2a) are reported for the first time. The new compounds have been characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, electronic spectroscopy and mass spectroscopy. The mesogenic properties of these new materials were studied by differential scanning calorimetry and optical microscopy. The electrical dark conductivities (σd) and photoconductivities (σph) of deposited films of 1a and 2a were investigated in various media with different concentrations of oxygen. Molecular oxygen increases photoconductivities (σph) significantly. The photoconductivity mechanism and formation of Pc+ which is positive charge carrier under the light irradiation of the phthalocyanine molecules are demonstrated using the theoretical calculations. The geometries of the oxotitanium(IV) phthalocyanines (TiOPc) are optimized with PM3 semi-empirical method, and their visible absorption maxima are calculated with ZINDO/S method. The results agree well with the observed values. It was found that for the calculation of visible absorption of neutral and positively charged substituted TiOPc molecules using ZINDO/S method could rapidly yield excellent results. Dipole moment, HOMO, LUMO energies and atomic charges are also calculated for clarification of the oxygen effect on the photoconductivity using PM3 and ZINDO/S methods. |
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Keywords: | Phthalocyanine Oxotitanium phthalocyanine Conductivity Photoconductivity Oxygen effect Semi-empirical calculations |
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