| Owning to the damage of oxygen free radical on human body and the excellent biological activity of pyrimidine derivatives, three series of rare earth?RE? complexes based on pyrimidine derivatives were synthesized in this paper and their inhibiting and scavenging capacities on superoxide free radical and hydroxyl free radical were evaluated.?1?Three series of rare earth?La???, Nd???, Sm???, Y???? complexes based on 2-[?4,6-dimethyl-2-pyrimidinyl?thio] acetic acid?HL1? and 1,10-phenanthroline?Phen?; 3-[?4,6-dimethyl-2-pyrimidinyl?thio] propanoic acid?HL2?; HL2 and Phen, were prepared and characterized by IR, UV-Vis, TGA and single crystal X-ray diffraction. The general formula of HL1-Phen-RE complexes is RE?L1?3Phen·nH2O?La???: n = 0; Nd??? and Sm???: n = 1; Y???: n = 2?; general formula of HL2-RE complexes is RE?L2?3·H2O; general formulae of HL2-Phen-RE complexes are [La?L2?3?Phen??H2O?]2·?Phen?2?H2O?8 and [RE?L2?3?Phen?]2·nH2O?Nd??? and Sm???: n = 2; Y???: n = 0?. The molecular structures of HL1-Phen-Nd???, HL2-Phen-La???, HL2-Phen-Nd???, HL2-Phen-Sm??? and HL2-Phen-Y??? complexes were confirmed by single crystal X-ray diffraction. The result illustrates that all of above five compelxes are binuclear structure bridging by four deprotonated pyrimidine carboxylic acid ligands. The coordinatin numbers of center rare earth ions are nine. ?-? stacking interactions could be found between pyrimidine rings and Phen rings of nearby HL1-Phen-Nd??? molecuars. Similarly, between Phen rings of nearby HL2-Phen-Y??? molecuars, ?-? stacking interactions exist as well.?2?Pyragallol autoxidation method was used to evaluate the inhibiting activity of free ligands and complexes on superoxide free radical. The result illustrates that all of the complexes own the obvious inhibiting activity. There is a positive correlation between the sample concentration and their antioxidant ability. Meanwhile, the inhibiting abilities of complexes are higher than those of the free pyrimidine carboxylic acid ligands. Homoleptic complex of Y??? with HL2(IC50: 0.0810 mmol·L-1) owns the highest antioxidant ability.?3?Fenton-salicylic acid system was used to evaluate the scavenging activity of free ligands and complexes on hydroxyl free radical. Homoleptic rare earth complexes with HL2 show the obvious scavenging activity. There is a positive correlation between the sample concentration and their antioxidant ability. Homoleptic complex of Nd??? with HL2(IC50: 0.154 mmol·L-1) owns the highest antioxidant ability. However, HL1, HL2, and their ternary rare earth complexes with Phen do not show obvious hydroxyl free radical scavenging activity under Fenton-salicylic acid system. |
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