Synthesis And Third-order Optical Nonlinearity Of Schiff Base Porphyrin

Nowadays, the theory of nonlinear optics has been developed deeply. However,with the ever-lasting emergence of a wealth of original materials, some research groupsnever stop looking for nonlinear optical materials with excellent properties. It is of greatsignificance to explore the properties of organic materials because of their merits suchas the structure with flexible tailor and adjustable performance, etc. By improving thethird-order optical nonlinearities of the organic materials, which can be utilized to somefields extensively such as photoelectric devices and optical limiting devices.Porphyrins are a class of organic compounds with a large π conjugated system,which can induce electron delocalization effect and possess superior nonlinearperformance. It is well known that strong charge transfer in the molecular is given toSchiff base by virtue of-C=N-. Therefore, such materials are worthy of investigation ingreat detail. Here, we attempt to combine the structure of the Schiff base with peripheryof porphyrins. Meanwhile, whether can be enhanced of the optical nonlinearity ofporphyrins or not is researched. The main purpose in this paper is to examine syntheticprocess, characterization of structure, the measurement of nonlinear optical coefficientsby using Z-scan technique, and optical limiting test based on Meso-tetra (schiff basesubstituted phenyl) porphyrins with four kinds of substituents.The structures of the above proposed Schiff base porphyrin（Sb-P） molecules areoptimized by the application of Gaussian software. By establishing correspondingmodel, the electron cloud distribution of the electrons occupied the highest orbital andelectrons no occupied the lowest orbital, energy gap, and dihedral angle are attained.The results indicates that the Sb-P have better conjugacy compared with the usualporphyrins.Subsequently, by considering the effects of Catalyst, acid, reaction time, and theorder of the additive reactants on production of the porphyrins, the desired samples areprepared and the optimal experimental conditions are obtained. This provides aneffective approach for the synthesis of the Sb-P. Moreover, the properties of theprepared samples are characterized by using several of chemical characterizationmethods such as UV-Vis absorption spectroscopy, Fourier infrared spectroscopy, and liquid on-line mass spectrometry fluorspar. The researched results validate theeffectiveness and reasonableness of the synthetic the Sb-P.On the basis of nanoseconds Z-scan experiment, the effective nonlinear refractivecoefficients and effective nonlinear absorption coefficients of all kinds of samples aremeasured. The second-order hyperpolarizabilities of the molecules are further calculated.On the one hand, in contrast to ordinary porphyrins and other nonlinear opticalmaterials in terms of the quantum chemical calculation, it validates that the Sb-P havelarger third-order optical nonlinearities from the viewpoint of experiment. On the otherhand, by comparing the proposed four kinds of Sb-P with different substituents, itillustrates that the Sb-P with Cyanogroup possesses the strongest second-orderhyperpolarizability. Several of advantages, including fast response and low threshold,are manifested in the Optical limiting experiment, thus the Schiff base porphyrins canbe considered as an excellent materials in terms of optical limiting devices.