Synthesis And Investigations Of Optical Properties, Electrochemical Properties And EPR Properties Of Porphyrin Compounds

Porphyrin compounds are a kind of macrocyclic conjugated organic molecules which have an extensive system of delocalizedπelectrons. They can be applied in many fields, such as macromolecule materials, chemical catalysis, electroluminescence materials and photodynamic therapy. Porphyrin oligomers have better properties in electron transfer, energy conversion, molecular devices and nonlinear optical materials than monomers. So there become very popular realm in synthesis and investigation of porphyrin oligomers.Recently, the rapid developments in electrommunication and computer technique lead to a need for smaller and more complex electronic devices. How to produce electronic devices at molecular level in molectroics is a problem concerned. Develop molecular devices at molecular level is the way to resolve this problem. Porphyrin oligomers are the chief choose as molecular devices materials by some scientists because of their unique photophysics and photochemical properties.Recently, synthesis and characterization of porphyrin oligomer arrays have been widely investigated. In reactive arrays, particular physical and optical properties are produced through electronic interaction in porphyrin oligomers or metalloporphyrin oligomers. The important development of porphyrin constructs leads to synthesize a lot of new compounds with different substitutes.Our final approach is to synthesize the envisioned molecular device by different type and definite ratio of hydroxyphenyl porphyrin linking with some bridge ligands, so hydroxyphenyl porphyrin isomers to be synthesized and be separated are particularly attractive and useful because they are the key reactants in preparing the target products. In this paper, five kinds of porphyrin monomers are synthesized and characterized while these are the specific cases in this paper. The five compounds are characterized by elemental analysis, MS, 1HNMR, UV-vis, IR which proved that these compounds are the target products.Secondly, one-dimensional porphyrin oligomer is synthesized by bridge-linking group (fumaryl chloride). And the target compound is charactered and identified by elemental analysis, MS, 1HNMR, UV-vis and IR, respectively.Thirdly, in this paper, fluorescence properties, third order nonlinear optical properties, optical limiting properties, transient photovoltage properties, electrochemical properties and EPR properties of porphyrin monomers, oligomers and metalloporphyrins are studied.1. Synthesis and character of series of hydroxyphenyl porphyrins According Adler-longo method, we synthesize the mixture containing six kinds of porphyrin compounds by using benzaldehyde, pyrrole and p-hydroxybenzaldehyde according the ratio of 1:2:1. The crude product is separated by using silica gel (zcx-Ⅱ, 100~200) column chromatography with chloroform as the eluant. Finally, we attain the five kinds of hydroxyphenyl porphyrin. The products are confirmed by element analysis, MS, 1HNMR, UV-vis and IR, respectively.2. Synthesis and character of trans-configuration porphyrin dimer and transition metal dimersThe reaction process can be represented by equation:The identities of the products are confirmed by element analysis, MS, 1HNMR, UV-vis and IR, respectively.3. The properties investigation of porphyrin compounds(1)The fluorescence propertyIn the paper, we study the fluorescence properties of porphyrin monomers, porphyrin dimer and metalloporphyrins, and obtain the quantum yield of these compounds at room temperature. The fluorescence intensity and the quantum yield of porphyrin dimer linked by anhydride are the highest in all compounds in the paper. The transitional metal on center of porphyrin ring quench the fluorescence of porphyrin except Zn porphyrin, the result is same with reference.(2)The third order nonlinear optical property and optical limiting propertyPorphyrin is conjugatedπ-system, can be modified by many methods. In the paper, we study the third-order-nonlinear and optical limiting properties of porphyrin compounds. The result showed that the porphyrin peripheral group and polymeric property influence on the third-order-nonlinear and optical limiting properties.(3)The transient photovoltage propertyIn the paper, we study the transient photovoltage property of porphyrins and metalloporphyrins. We found that porphyrin monomers and porphyrin oligomers linked electron-donating group showed strong transient photovoltage response, and metalloporphyrins showed weak transient photovoltage response except Cu porphyrins.(4)The electrochemical propertyThe redox properties of all porphyrins are researched by the cyclic voltammetry, and the redox potentials are obtained. Porphyrins normally undergo two one-electron reductions and two one-electron oxidations. Two porphyrins within a porphyrin array are in electronic communication then the reduction or oxidation of one porphyrin ring can affect the redox properties of the second porphyrin ring. (5)The EPR propertyIn the paper, we study the EPR property of series of hydroxyphenyl porphyrins, porphyrin dimers and metalloporphyrins. We find that the EPR signals of porphyrins which linked an electron-donating substituent are stronger than that of porphyrins which linked an electron-drawing substituent. Metalloporphyrins with different number of d electrons show different EPR spectra.