| In this study, the porphyrin-POM hybrids composed of different Keggin type POMs and tetraphenylporphyrin are prepared and characterized. The modulatable third-order nonlinear optical properties, as well as reversibility, of these hybrids in different redox states are studied by Z-scan technique associated with electrochemical station. The mechanism of the modulation of the third-order nonlinear optical properties of porphyrin-POM hybridsis also discussed. The main content of this thesis is as follows.1. Two electrovalently connected tetraphenylporphyrin-POM hybrids, [H2TPP] [HPW12O40]·2C4H8O·2H2O （TPP-PW） [H2TPP][HPMo12O40]·5C4H8O·5H2O （TPP-PMo） are synthesized according to the methods of literature, respectively. Electrochemical properties of the reactants tetraphenylporphyrin and polyoxometalates as well as the hybrids TPP-PW and TPP-PMo are studied by using an electrochemical station. Comparing the the redox potentials of hybrids with the reactants tetraphenylporphyrin and polyoxometalates, the redox potentials assigned to POMs moiety shift to the negative direction, while the redox potentials assigned to tetraphenylporphyrin moiety shift to the positive direction in the resulting hybrids. Different redox states of the two hybrids are controlled by using electrochemical station, Z-scan measurements are operated at the same time. Whatever the redox state is, the second-order hyperpolarizability values of the two hybrids decrease compared to the original state. The second-order hyperpolarizability values （y） of TPP-PW and TPP-PMo can be reversibly swiched under different voltage. The y values of TPP-PW under the voltage of-0.95V,0V,0.7V （vs Fc+/Fc） are （2.27±0.15）X 10-28（esu）, （2.70±0.15）× 10-28（esu）, （2.34±0.15）×10-28（esu）, respectively. The γ values of TPP-PMo under the voltage of-1.75V,0V,0.7V （vs Fc+/Fc） are （2.45±0.15）± 10-28（esu）, （2.75 ± 0.15） ± 10-28（esu）, （2.28 ± 0.15） ± 10-28（esu）, respectively. By calculating and analyzing molecular orbital level, it is known that the intramolecular electron or change transfer between the POM moiety and tetraphenylporphyrin moiety in the hybrids becomes difficult when losing or accepting electrons, which is responsible for decreasing second-order hyperpolarizability values after electrolysis.2. A covalently connected porphyrin-POM hybrids, {（TPP）Zr(PW11O39)[（n-C4H9）4N]5} (ZrTPP-PW11) is synthesized according to the methods of literature. Electrochemical properties of the reactants （TPP）Zr（OAc）2 （ZrTPP） and polyoxometalate TBA-PW11 as well as the resulting hybrid ZrTPP-PW11 are studied by using an electrochemical station. Comparing the the redox potentials of the hybrid with ZrTPP and polyoxometalates, the redox potentials assigned to POM shift to the negative direction, while the redox potentials assigned to ZrTPP shift to the positive direction. Different redox states of the two hybrids are controlled by electrochemical station, Z-scan measurements are operated at the same time. Whatever the redox state is, the second-order hyperpolarizability values of the two hybrids decrease compared to the original state. The second-order hyperpolarizability values of (ZrTPP-PW11) can be reversibly swiched under different voltage. The y values of ZrTPP-PW11 under the voltage of 0V,0.7V （vs Fc+/Fc） are （3.33±0.15）×10-28（esu）, （2.35±0.15）X 10-28（esu） (30% less than （3.33 ±0.15）×10-28（esu）). By calculating and analyzing molecular orbital level, the intramolecular electron or change transfer between the part of POM and ZrTPP in the hybrids is becomes difficult when losing or accepting electrons., which is the reason of decreasing second-order hyperpolarizability values after electrolysis. |
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