Synthesis And Function Studies On New Porphyrin Lanthanide Liquid Crystals Compounds

As the particular structure and the nature of the porphyrins, they areimportance in the field of photo-electronic conversion, biomimetic,catalytic materials,gas sensor, solar storage, microanalysis, etc.Today, the research of porphyrin derivation are active more andmore.Porphyrin is a big conjugate annular compound, its periphery has 12active positions, which could link up different structures soft sidechains. So, we would synthesize new type compound of liquid crystalporphyrin with special properties by molecular design.Since Goodby et. al synthesized the first liquid crystal in 1980, anew type of liquid crystal material has been developed rapidly. Liquidcrystal porphyrin may be used as semiconductor or photoconductormaterials, scientists gave paid close attention to its photoeletronicproperty. In 1989, liquid crystal porphyrin was first used in colordisplay by Kubota. In 1990 Yamamota. I. made a display instrumentfrom synthesized benzoporphyrin and its liquid crystal metal porphyrin.According to references synthesized liquid crystal porphyrins haveproblems of higher temperatures of liquid crystal phase, higherviscosity of liquid crystal phase and a narrow mesophase range, as aresult, restrict the application of liquid crystal porphyrin. Since C. P.Wong synthesized the first lanthanide porphyrin complex in 1974,which is meso-tetraphenyl porphyrin Europium (III), a new type ofporphyrin complexes has been developed rapidly. Especially in 1983,Buchler and his colleagues synthesized the first sandwich lanthanideporphyrin complex, then opened a new researching field. Synthesis and properties of rare earth porphyrin and rare earthporphyrin liquid crystal complexes are introduced, fifty-nine newcompounds are divided six series in this paper. These compounds havebeen characterized by elemental analyses, Uv-vis, IR spectra, NMR,DTA, TGA and molar conductance. The structures are proposed. Theliquid crystal properties have been researched by DSC, polarizedmicroscopic observation and X-ray diffraction. The mesophasestructures are probably a hexagonal discotic columnar Colh. Besides, these compounds were studied by means of cyclicvoltammetry, surface photovoltage and luminescence spectroscopies.I. Syntheses of the complexes: In this paper synthesis method of the ligands, rare earth porphyrins,and rare earth porphyrin liquid crystal complexes are introduced,fifty-nine new compounds are divided six series.Structures of the ligands are follows:(1) 5, 10, 15, 20 –tetra -[para -methoxyphenyl] porphyrin H2(P-CH3O)TPP, R1=R2=CH3O, R3=H(2) 5,10,15,20-tetra-[para-chlorophenyl]porphyrin H2(P-Cl)TPP, R1=R2=Cl, R3=H(3) 5,10,15,20-tetra-[(para-alkoxy-m-ethyloxy)phenyl]porphyrin, R3=OCH2CH3, R1=R2=O(CH2)nCH3 (n=11, 13, 15)(4) 5,10,15,20-tetra-[(para-alkacyloxy–m-ethyloxy)phenyl] porphyrin, R3=OCH2CH3, R1=R2=OCO(CH2)nCH3 (n=8, 10, 12)(5) (5-para-alkoxyphenyl-10, 15, 20-tri-phenyl)porphyrin, R1=R2= O(CH2)nCH3 (n=11, 13, 15), R3=H(6) (5-para -alkacyloxyphenyl-10, 15, 20-tri-phenyl) porphyrin, R1=R2=OCO(CH2)nCH3 (n=8, 10, 12), R3=H(1) 5,10,15,20-tetra-[para-methoxyphenyl]porphyrin Rare Earth Chloride H2(P-CH3O)TPP, R1=R2=CH3O, R3=H, R4=Cl, Ln= Dy, Ho, Tm, Yb, Lu (2) 5,10,15,20-tetra-[para-chlorophenyl]porphyrin-Hydroxy-Rare Earth Complexes H2(P-Cl)TPP, R1=R2=Cl, R3=H, R4=OH, Ln=Gd, Tb, Dy, Er, Yb, Lu (3) 5,10,15,20-tetra-[ (para-alkoxy-m-ethyloxy)phenyl] porphyrin Hydroxy Rare Earth Complexes, R3=OCH2CH3, R1=R2= O(CH2)nCH3 (n=11, 13, 15), R4=OH, Ln=Ho, Tb, Dy, Er, Yb (4) (5-para-alkoxyphenyl-10, 15, 20 -tri-phenyl) porphyrin Hydroxy Rare Earth Complexes, R1=R2=O(CH2)nCH3 (n=11, 13, 15), R3=H, R4=OH, Ln=Ho, Tb, Dy, Er, Yb (5) (5-para-alkacyloxyphenyl-10, 15, 20-tri-phenyl) porphyrin Hydroxy Rare Earth Complexes, R1=R2=OCO(CH2)nCH3(n=8, 10, 12), R3=H, R4=OH, Ln=Ho, Tb, Dy, Er, YbII. Characterization of complexes These complexes have been characterized by Elemental analyses,Uv-vis, IR spectra, NMR, DTA and TGA, Molar Conductance. Inconclusion, one molecular porphyrin ligand is coordinated to alanthanide ion in a tetradentate fashion and a hydroxyl group iscoordinated to the same lanthanide ion. Therefore, the coordinationnumber of the central rare earth ion is five.Ⅲ. Surface photo-voltage spectroscopy (SPS) We investigated the photo-generated charge behavior of the ligandand the complex, by means of surface photo-voltage spectroscopy(SPS) and field induced surface photo-voltage spectroscopy(FISPS).The SPS of the ligand and the complex follow the absorption spectraresponse well, indicating that they are corresponding to similarelectron transition process. Electric and photo-voltaic properties ofsolid porphyrins have been attributed to the semiconducting behaviorof the porphyrins themselves rather than insulator.Ⅳ. Luminescence spectroscopy Luminescence spectroscopy of fourteen ligands andcorresponding complexes were introduced in the paper. Quantumyields Φf were obtained at room temperature. Φf of the S1→S0fluorescence of the porphyrins are lower than 0.21.Ⅴ.Cyclic voltammetry The oxidation and reduction properties of the compounds wereresearched by the cyclic voltammetry, the oxidation-reduction...