Synthesis, Spectroscopic, and Biological Studies on New Zirconium(IV) Porphyrins with Axial Ligand

Abstract

A series of parasubstituted tetraphenylporphyrin zirconium(IV) salicylate complexes (SA/5-SSAZr(IV)RTPP, R = p-H, p-CH3, p-NO2, p-Cl, SA = salicylate, and 5-SSA = 5-sulfosalicylate) have been synthesized, and the spectral properties of free base porphyrins, their corresponding metallated, and axially ligated zirconium(IV) porphyrin compounds were compared with each other. A detailed analysis of ultraviolet-visible (UV-vis), proton nulcear magnetic resonance ((1)H NMR) spectroscopy, infrared (IR) spectroscopy, and elemental analysis suggested the transformation from free base porphyrins to zirconium(IV) porphyrins. The ability of the metal in this complex for extra coordination of solvent molecules was confirmed by ESI-MS spectra. Besides the fluorescence, cyclic voltammetry, and thermogravimetric studies, the complexes were also screened for antimicrobial and anticancer activities. Among all the complexes, 5-SSAZr(p-NO2TPP) shows high antibacterial activity.

Figure 1

UV-Vis overlapped (a) B bands (b) Q bands of TPP and (Cl)₂ZrTPP in chloroform.

Figure 2

UV-vis spectra of SAZrTPP (a) B bands (b) Q bands in different solvents.

Figure 3

S₁ → S₀ fluorescence spectrum of (a) SAZr(p-CH₃TPP) and (b) 5-SSAZr(p-CH₃TPP) in DMSO (C = 10⁻⁶ mol L⁻¹, λ _exc = 420 nm).

Figure 4

Cyclic voltammogram of Zr(p-CH₃TPP) in CH₂Cl₂ containing 0.1 M (TBA)PF₆. Scan rate 20 mV/s.

Figure 5

TGA (black line) and DTA (yellow line) picture of SAZrTPP.

Figure 6

Cytotoxicity of SAZr(p-CH₃TPP) and 5-SSAZr(p-CH₃TPP), where 2a = p-CH₃TPP.

Figure 7

Proposed structure for axially ligated zirconium(IV) porphyrin complexes.

Scheme 1

General synthetic route for the synthesis of tetraphenylporphyrin and its parasubstituted derivatives.

Scheme 2

General synthetic route for the synthesis of dichloro(tetraarylporphinato)zirconium(IV).

Scheme 3

General synthetic route for the synthesis of axially ligated Zr(IV) porphyrins complexes.