2004 Volume 72 Issue 2 Pages 84-91
The reaction of titanium diisopropoxide bis(acetylacetnate) and titanium tetraisopropoxide with several organic diols gave novel linear and net-worked alternative titanium-organic moietes hybrid copolymers. The forms and sizes of the net-worked alternative titanium-organic moietes hybrid copolymers were found to vary with the organic units. The UV-VIS and ESR spectra of the products were taken to estimate their electronic properties. The UV-VIS spectra of both linear and net-worked hybrid copolymers having conjugated organic moieties were found to appear at longer wave lengths, and further their ESR spectra indicated a peak due to the organic radical spieces. These results strongly suggested that an electron transfer from the aromatic moieties to the titanium atom occurred in the alternating hybrid framework. The signal intensities of the ESR spectra were shown to increase in the net-worked system compared with the linear system. To investigate the electron transfer process, the ab-initio calculations of the monomer models were done, indicating that in the models having the conjugated organic groups the HOMO is delocalized on the organic moieties, while the LUMO is localized on the titanium atom by analyzing the LCAO coefficients of the models. It was thus deduced that the electron transfer occurs from the organic moiety to the titanium atom with reduction of titanium from + 4 to + 3.
