Synthesis and characterization of axially ligated zinc(II)-para-nitro-mesotetraphenylporphyrin

Department of Chemistry, University of Jammu, New Campus, Baba Sahib Ambedkar Road, Jammu-180 006, Jammu & Kashmir, India E-mail : gauribajju@gmail.com Manuscript received 10 December 2010, accepted 09 March 2011 Reaction of p-nitro-meso-tetraphenylporphyrin (p-NO2-H2 TPP) with zinc(n) acetate (Zn(OAc)2) and phenol result in the formation of corresponding axially ligated zinc(II)-p-nitro-meso-tetraphenylporphyrin (X-ZnII-p-NO2 TPP) (where X = axial phenolic ligands and TPP = tetraphenylporphyrin). The four-coordinated zinc porphyrin will accept one and only one axial ligand in 1 : 1 molar ratio to form five-coordinated complexes (Fig. 1), which are purified by column chromatographic method and characterized by UV/Vis, IR, NMR, Mass and elemental analysis. The visible spectra of the compounds in different solvents show a red shift (bathochromic shift) which increases in the magnitude depending upon the charge and polarizability of the axial ligation to Zn-p-NO2TPP but not on the strength of the zinc ligand bond. The IR spectra show the appearance of metal-nitrogen (Zn-N) and metal-ligand (Zn-X) vibrations. The 1H NMR results in CDCJ3 indicate the merging of protons of the phenolic ring axially attached to the central metal ion with that of the tetraphenyl ring of the Zn-p-NO2TPP. The Mass spectra show that the molecular weight of the porphyrin agree well with the calculated m/z values. The elemental analysis shows the percentage of various elements In the compounds formed