Metal-free, metallo-porphyrazines, monomeric bisaxial complex [FePz(py)₂] and the bridged complex [FePz(pyz)]_n with eight (4-thiobutyl 4-biphenylcarboxylate) groups

Abstract

Metal-free and metallo-porphyrazines (M = Mg, Co, Cu, Zn, and ClFe) carrying eight hydroxybutylthio groups at peripheral positions were prepared from 2,3-bis(4-hydroxybutylthio) maleonitrile. The hydroxybutyl groups were incorporated by esterification of porphyrazine derivatives with 4-biphenylcarboxylic acid in the presence of dicyclohexylcarbodiimide and p-toluenesulfonic acid. Unlike the parent porphyrazine, the symmetrically functionalized porphyrazines with eight ester units were soluble in common organic solvents such as chloroform, dichloromethane, tetrahydrofuran, acetone, and toluene and insoluble in water and n-hexane. Chloro-octakis(4-thiobutyl 4-biphenylcarboxylate) porphyrazinato iron(III) (FePzCl) was prepared by the reaction of metal-free porphyrazine with iron(II) acetate and further treatment with HCl solution. The monomeric bisaxial complex [FePz(py)₂] and the bridged complex [FePz(pyz)]_n were formed as stable complexes by reacting FePzCl with pyridine and pyrazine, respectively. The newly synthesized compounds were characterized by elemental analysis, FT-IR, UV‒vis, mass, ¹H and ¹³C NMR spectroscopy.

Graphical abstract

Keywords:

• Porphyrazine
• 4-Biphenylcarboxylic acid
• Esterification
• Shish kebab type oligomer
• Iron