Synthesis, Characterization And Metallization Of Matrix Materials In Oligomeric Porphyrins

Porphyrins are big conjugated macrocycle compounds. Their peripheries have 12 active positions, which could connect with different function groups to enhance the conjugation of planar constitution, multiformity of conformation and properties self-assembly. The high speed development in electron technology needs more complex and smaller electron parts of an apparatus. So an important task in electronic region is how to develop new technology to product electronic part of an apparatus on the molecule level. Owing to the structure of alternate single-double bonds conjugate, porphyrin monomer can make electron transfer faster and easier. Therefore, it is possible that the metals in the square can be substituted by porphyrins to serve as the extensive-conjugated structure.Metalloporphyrins are the compounds which the 2 H atoms in porphyrins are submitted by metal ions. Two N atoms conjoin the metal ions by covalent bond meanwhile the other two N atoms make the coordination bond. Metalloporphyrins have broad research foreground and application value because of their excellent properties in organic light conduct, bionic green catalysis, manual work of the function of biology molecules and they can be use as hostmolecules to identify other molecules. The designing and preparation of a series of mono-porphyrins are popular areas of research, for oligomeric porphyrins play a number of very important biological roles such as energy and electron transfers, molecular binding, multi-electron redox catalysis, light harvesting and organic magnetic materials.A series of hydroxyphenylporphyrins and different transition metalloporphyrins (Mn, Fe, Co, Ni, Cu, Zn) were parpared and purified, and they were studied systemically by means of fluorescence property, EPR property, transient photovoltage property, electrochemistry property and TGA-TDA thermogram. All these compounds were identified by Element Analysis, mass spectrum, IR, UV-vis and 1HNMR. The correlation between the structure of compounds and the electrons in d orbit were discussed and their specific spectra were explained, and gain some disciplinarian conclusions.1,Synthesis and metalize of porphyrins(1) Synthesis According to Adler method, we synthesized the mixture containing6 kinds of porhpyrins by using benzaldehyde, pyrrole and p-hydroxybenzaldehyde according to the ratio of 1:3:4.According to Adler method, we synthesized metalloporphyrins by churning up the MHTPP and metal chloride in boiling DMF.(2) Separation and purification of the mixtureThe crude product was separated by using silica gel column chromatography and thin layer chromatography with suitable solution. Finally, we attained five kinds of porphyrins with nearly yield.We use the same method and gained metalloporphyrins.2,the characteristics of porphyrins(1) Elemental analysis and mass spectraSatisfactory elemental analysis of C, H, N were obtained for five porphyrins and six metalloporphyrins within permissible limits. The MS analyses were consistent with the theoretical result.(2) ~1HNMR spectraAll the compounds were determined in CHCl3 using TMS as the internal standard. The inner proton (N-H) signals of five free porphyrins isomers were located at the highest field region due to extensive ring current interaction, around -2.79 ppm. The resonances of hydroxyl hydrogen occurred at about 10.10 ppm, and other peaks appeared at low field region of 7.30 to 10.10 ppm.There were not any peaks in the region of -4~0 ppm in the six metalloporphyrins. The electrons in d orbit in metal ions lead to the peaks move to lower field. (3) UV-Vis spectraThe characteristic absorption of free porphyrins are displayed in UV spectra of compounds, with a typical set of Soret band and four Q bands in visible region. The spectral profiles showed no fundamental difference among these compounds except for the relative intensities. It is indicated that the number of hydroxyl group attached to phenyl p-position has little effect on the electron delocalization.Comparing with the free porphyrins, the Soret bands shifted and the numbers of Q bands decreased in metalloporphyrins.(4) Infared spectraPeaks could be observed at 3 320 cm-1 in free porphyrins and that they were the typical peaks ofνN-H(pyrrole). They disappeared when the free porphyrins were metalized, and the peaks around at 970 cm-1shifted to 1 000 cm-1 because of the influence of metal ions.3,Study of hydroxyphenylporphyrins properties(1) Fluorescence propertyAll the free porphyrins are highly conjugated. Fouorescence spectra showed that they possess stronger fluorescence property. The emission fluorescence of different porphyrins is mainly concerned not only with porphyrin macrocycles, but also with the number of p-hydroxyphenyl on the meso-.The metal ions had very strong quenching effects for the fluorescence intensity.(2) EPR propertyPorphyrins are a kind of macrocyclic organic molecules which have an extensive system of delocalizedπelectron. The EPR signals of porphyrin compounds were generated by the interaction between delocalizedπelectrons of porphyrins or unpaired electrons of metal ions and magnetic field. The electron paramagnetic resonance spectroscopic data obtained for the photoexcited triplet state of a series of conjugated porphyrin compounds indicate that the changes of electron density and molecule symmetry have some influence on the EPR g value.(3) Transient photovoltage propertyTransient photovoltage properties of porphyrins and metallo- porphyrins were studied. The relationship of photogenerated electron–hole full separation time was that porphyrin monomer was faster than that of metalloporphyrins. The transient photovoltaic signal of porphyrin-Cu is the especial one in metalloporphyrins. It was similar as metal free porphyrins, and also similar as metalloporphyrins. The difference of central ions had different influences about separation rate of charge carriers.(4) Electrochemistry propertyHydroxyl as an electron-donating substituent on the peripheral positions of porphyrin ring results in an increase in the average electron density of the total conjugated porphyrin system as a result of easier oxidation and more difficult reduction.(5) TGA-TDA thermogram properThe heat stability of p-hydroxyphenylporphrins is concerned with the number and the symmetry property of hydroxyphenyl on meso- of porphrin marocycle. The number of p-hydroxyphenyls is more, the heat stability is worse (except THPP). The heat stability of unsymmetry structure is worse than that of symmetry structure.In metalloporphyrins, whenπfeedback-bands have dominant influence to the average electron density of porphyrin which decrease the energy for electron transition, their heat stability are worse than the free porphyrin, vice versa.