Investigation On Nonlinear Optical Properties Of Two Kinds Of Novel Porphyrins Materials

Nonlinear optical materials with strong nonlinear optical effects and fast response time are designed and synthesized due to their wide applications in various fields,such as 3D optical storage,micro-fabrication,optical limiting,and photodynamic therapy.Designing and synthesizing nonlinear optical materials not only require efficient synthesis methods,but also need an in-deep understanding of the relationship between molecular structures and photophysical properties.Porphyrins have a large?-electron conjugation system,diversely molecule structures,rich functions,and stable physiochemical properties.They are widely used in biomedical applications,optical communications,optical switching,and optical limiting.Due to their fast and strong nonlinear optical effects,most investigations on the photophysical properties of porphyrin compounds have been reported in recent years.The innovations of this thesis are as follows:Firstly,the solvent effects on the effective three-photon absorption of Zn?II?-[meso-tetrakis?4-octyloxyphenyl?porphyrin]were investigated;Secondly,the effects of central metal substitution to modify the meso-tetrakis?4-octyloxyphenyl?porphyrin were analyzed.The main contents of this thesis include:1.The structure,physicochemical properties,and the nonlinear optical properties of porphyrins were introduced.The basic theories of the nonlinear optical effect were described;the Z-scan technique was introduced in detail,and the principle of evaluating the nonlinear optical coefficients from the Z-scan experiments was analyzed.The Z-scan measurement systems were tested by the standard samples,e.g.,CdS and CS₂,and the reliability and sensitivity of the measurement system was discussed.2.Solvent effects on the fluorescence and effective three-photon absorption properties of Zn?II?-[meso-tetrakis?4-octyloxyphenyl?porphyrin]were studied.Firstly,the molecular structure of Zn?II?-[meso-tetrakis?4-octyloxyphenyl?porphyrin]was characterized by infrared spectroscopy.Secondly,the linear absorption spectra of Zn?II?-[meso-tetrakis?4-octyloxyphenyl?porphyrin]in three solvents were analyzed.Thirdly,the changes in the fluorescence properties of Zn?II?-[meso-tetrakis?4-octyloxyphenyl?porphyrin]in three solvents were studied.Then,the effective three-photon absorption properties of Zn?II?-[meso-tetrakis?4-octyloxyphenyl?porphyrin]under the femtosecond-pulsed excitation at the wavelength of 800nm were investigated.The corresponding effective three-photon absorption coefficients and cross-sections were evaluated.Finally,the dependence of the normalized transmittance on the incident intensity of three solutions was analyzed,and their application in the field of optical limiting was discussed.3.The investigations on the nonlinear absorption properties of free-based porphyrin and metalloporphyrin were carried out.Firstly,the similarities and differences between the linear absorption spectra of meso-tetrakis?4-octyloxyphenyl?porphyrin and Zn?II?-[meso-tetrakis?4-octyloxyphenyl?porphyrin]were studied.Secondly,the underlying mechanisms originating from the fluorescence properties of the two porphyrins were analyzed;thirdly,under the same excitation conditions,the changes in the nonlinear absorption properties of both the free-based porphyrin and zinc porphyrin were studied;finally,the significance of the central metal substitution for controlling the nonlinear optical properties of the meso-tetrakis?4-octyloxyphenyl?porphyrin and their applications were discussed.