[Synthesis and spectroscopic properties of tetra-(dimethylaminophenyl) porphyrin and its metal complexes].

Abstract

Porphyrin and metalloporphyrin distribute widely in nature and they play an important role in the life. Synthesis of porphyrin compounds with special function has been the focus of attention. In the present paper, porphyrin and metalloporphyrin compound were synthesized by the following method: by one-step synthesis, tetra-(dimethylaminophenyl) porphyrin (T(DMAP) P) was synthesized with propionic acid, acetic acid and nitrobenzene as solvent and 4-dimethylaminobenzaldehyde and pyrrole as raw material. The yield was 24.24%. The complexes of T(DMAP)P with Zn2+, Mn2+ and Tb3+ were synthesized by solvent of chloroform-N, N dimethylformamide (1 : 1). The effects of solvent, temperature and reaction time on the reaction were discussed. Optimum proportion between porphyrin and metallic salts was studied also and the molar ratios of T(DMAP)P to Zn (CH3COO)2 x 2H2O, T(DMAP)P to MnCl2 x 4H2O, and T(DMAP)P to TbCl3 were 1 : 1.2, 1 : 1.4, 1 : 1.5, respectively. The synthesis of metalloporphyrins under mild conditions is simper with high yield (94.2%, 91.7% and 90.5% for T(DMAP) P combined with Zn2+ , Mn2+ and Tb3+ respectively) and the unstability of metalloporphyrin could be avoided. The constitution and structures of these compounds were studied by elemental analyses, infrared spectrum (IR), and ultraviolet-visible spectrum (UV-Vis). The conductivity of porphyrin compound with different concentration and temperature was studied. It was found that the molar conductivity of T(DMAP)P-TbCl(74.6 s x cm(-2) mol(-1)) was greater than that of T(DMAP)P-Zn (8. 8 s x cm(-2) x mol(-1)) and T(DMAP)P-Mn (25.8 s X cm(-2) mol(-1)). So T(DMAP) P-TbCl could be regarded as the 1 : 1 electrolyte compound while T(DMAP)P-Zn and T(DMAP)P-Mn were non-electrolyte compounds. The influences of different metal ions on the reaction were investigated. The discussion was concentrated on the molecular spectra of porphyrin and metalloporphyrin. Compared with tetraphenyl porphyrin, the absorption of T(DMAP) P and its metal complexes had red-shifts due to the substituent groups and metal ions. When the porphyrin rings were occupied by metal ions, the number of Q band decreased and the absorption peak intensity decreased. Among these metalloporphyrin compounds, the maximum absorption of T(DMAP)P-TbCl had the biggest red-shifts and could be used as ideal photosensitizer.