Synthesis and Characterization of New Tailed Histidine-Linked Porphyrins

A new histidine-linked porphyrin (1) and different transition metalloporphyrins [Zn (2), Co (3), Fe (4), Mn(5)] were prepared, purified and characterized by means of elemental analysis, IR, UV-Vis and (1)H NMR. The correlation between the structures of the complexes and their (1)H NMR, IR, UV spectra was discussed and their specific spectra were explained. Their fluorescence characters were studied with the aid of fluorescence spectra and the lowest energy conformation were chosen with 100 ps molecular dynamic simulation. The fluorescence intensity and the quantum yield of porphyrin 1 were low because of the electron-withdrawing group on peripheral porphyrin ring. The fluorescence intensity and the quantum yield of metalloporphyrin 2 were much weaker than those of the corresponding metal-free porphyrin 1 because zinc weakened the fluorescence radiation. Fluorescence signals had not been detected for metalloporphyrins 3-5 under the same experimental conditions because of the fluorescence quenching. The mininal energy conformations and binding mode of four host-gust systems were obtained by molecular minimize and quantum chemistry. The four host-guest complexes were investigated to predicte the coordinate bond on four transition metal.