Synthesis and characterization of axially modified Zn(II) porphyrin complexes for methylene blue dye oxidative degradation

In the present work, we report synthesis, structural elucidation and photophysical properties of new pentacoordinated Zn(II) porphyrinates (1-2). Complexes with formula [Zn(TEBOP)(DABCO)](DABCO) (1) [TEBOP = meso-tetrakis(ethyl-4(4-butyryl)oxyphenyl) porphyrinato), DABCO = 1,4-diazabicyclo [2.2.2] octane], and (2) [Zn(TEBOP)(pyz)] [pyz = pyrazine] have been studied to explore the effects of axial ligand on the structural and photophysical properties of [Zn(TEBOP)]. Both the solution and solid-state characterization unambiguously confirmed the pentacordinated nature of the complexes 1 and 2. The X-ray molecular structures showed that these complexes exhibited high ruffling deformation. We showed here that some of the optical properties (absorption features and quantum yield) could be modulated by varying the axial ligand whereas emission wavelength (lambda(em) ) and lifetime (tau(f)) values were found to remain unchanged. Electrochemical studies suggested that the characteristic reduction and oxidation potentials of the porphyrin ring varied with the axial ligand. Finally, [Zn(TEBOP)] and complexes 1 and 2 were checked for the oxidative degradation of methylene blue (C-0 = 30 mg/L, T = 22 degrees C, pH = 6, H2O2 = 4 mL/L). The degradation yields followed the order: [Zn(TEBOP)] + H2O2 (47%) > 2 (38.5.9%) > 1 (26.9%). (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

In this study, new pentacoordinated Zn(II) porphyrinates were synthesized and their structural elucidation and photophysical properties were investigated with different axial ligands. The optical properties could be modulated by varying the axial ligand, while the emission wavelength and lifetime remained unchanged. Electrochemical studies revealed variation in characteristic reduction and oxidation potentials of the porphyrin ring with different axial ligands. Additionally, oxidative degradation of methylene blue was examined, showing different levels of degradation yields for the tested compounds.