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ISSN 1998-9539

Synthesis, Electrochemical Properties and Antioxidant Activity of Hydroxy Substituted Tetraphenylporphyrins

Mariya V. Tesakova,a@ Alexander S. Semeikin,b and Vladimir I. Parfenyuka,c

aG.A. Krestov Institute of Solution Chemistry of RAS, 153045 Ivanovo, Russia

bIvanovo State University of Chemistry and Technology, 153000 Ivanovo, Russia

cKostroma State University, 156005 Kostroma, Russia

@Corresponding author E-mail: mvt@isc-ras.ru

 

DOI: 10.6060/mhc160319t

Macroheterocycles 2017 10(1) 43-50

 

Electrochemical and spectrometric studies of reaction of DPPH free radical with synthesized hydroxy substituted tetraphenylporphyrins, notably 5,10,15,20-tetrakis(2,4-dihydroxyphenyl)porphyrin, 5,10,15,20-tetrakis-[4-(2-hydroxy-ethyloxy)phenyl]porphyrin, 5,10,15,20-tetrakis[4-(4-hydroxybutyloxy)phenyl]porphyrin and their Zn complexes were carried out. The antioxidant activity of the studied porphyrins against DPPH has been found increasing in the following order: Н2T(4-О(СН2)4ОНPh)P ≈ ZnT(4-О(СН2)4ОНPh)P < ZnT(4-О(СН2)2ОНPh)P < Н2T(4-О(СН2)2ОНPh)P < ZnT(2,4-di-ОНPh)P < H2T(2,4-di-ОНPh)P. It has been established that 5,10,15,20-tetrakis(2,4-dihydroxyphenyl)porphyrin having eight OH-groups in the ortho- and para-positions of the phenyl rings has the greatest antioxidant activity. The absence of the antioxidant activity of 5,10,15,20-tetrakis[4-(4-hydroxybutyloxy)phenyl]porphyrin and its Zn complex, probably can be attributed to distant location of the OH-group from benzene ring of the macroheterocycle. The hydrocarbon chain between the benzene ring and OH-group makes difficulties for removal of hydrogen. In these porphyrins the substituent  in the benzene ring exhibits properties which are characteristic for the aliphatic alcohols. The introduction of metal into the macroheterocycles does not significantly affect the antioxidant properties of the porphyrins. For ZnT(4-O(CH2)2OHPh)P and ZnT(2,4-di-OHPh)P indicators of antioxidant activity are somewhat higher than for the respective ligands. The introduction of second OH-group in the o-position of the phenyl ring increases the antioxidant activity of OH substituted tetraphenylporphyrins. Probable mechanism of the porphyrins antioxidant action is hemolytic detachment of hydrogen from OH-group of their phenyl rings.

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