Two-Dimensional Metal-Porphyrin Framework:Design,Synthesis And Nonlinear Optical Properties

Metal-porphyrin framework(MPF)is an important class of metal-organic functional material developed in recent years,showing tremendous potential in catalytic,dye-sensitized solar cells,biological probes,anti-cancer drugs,gas separation,nonlinear optics,and etc.Meanwhile,the development of two-dimensional(2D)materials such as graphene spurred widespread interest in the development of 2D metal-organic functional materials due to their high crystallinity and designability,as well as their unique optical and electrical properties.Within this context,2D stable and functional MPF materials gradually emerged and have become an important sub-category of the 2D material family.In this thesis,we envisioned to synthesize new types of 2D MPF material that exhibit good third-order nonlinear optical properties from the material design perspective.As such,we designed a new porphyrin derivative,namely,meso-tetrakis(6-(hydroxymethyl)pyridine-3-yl)porphyrin(H2THPP),and subsequently obtained a 2D MPF of[CoTHPP]with crystalline platelet morphology,from its reaction with Co(NO3)2·4H2O under hydrothermal reaction conditions.By incorporating polyvinylpyrrolidone(PVP)in the reaction process,we subsequently obtained[CoTHPP]in two additional morphologies,viz.,the flower-shaped nanoclusters and the ultrathin films,depending on the PVP loading.We revealed that the formation of ditferent morphologies of[CoTHPP]is due to the intercalation of PVP into its 2D layers that prohibit the epitaxial growth of the crystallites.Accordingly,more PVP loading gives rise more dispersed nanosheets.By comparing the third-order nonlinear responses of the crystalline platelets,the flower-shaped nanoclusters,and the ultrathin films,we conclude that the nonlinear optical performance of[CoTHPP]is marginally enhanced when exfoliated into the nanoscale.giving a nonlinear transmittance(T)value of 0.54,absorption coefficient(?2)of 9.5 ×10-10 m·W-1,and second hyperpolarizability(?)value of 1.37 × 10-28 esu,and features as an ideal class of nonlinear optical materials.In addition,we further explored the reaction of porphyrin ligand,including H2THPP and its precursor complex meso-tetrakis(6-methylpyridin-3-yl)porphyrin(H2TMPP),with transitional metal sources,including Zn(?),Cd(?),and Mn(?),to give either 2D or one-dimensional(ID)structures,and discussed the effect of different metal cores in MPF on their third-order optical nonlinearity.