含鎳超氧化物歧化酶擬態化合物之電子效應

Abstract

此研究以本實驗室所開發的鎳超氧化物歧化酶擬態化合物的 2,6-bis(((S)-2-(diphenyl-hydroxymethyl)-1-pyrrolidinyl)methyl)pyridine (H2BDPP)配位基為基礎，將其苯環區及吡咯部分進行推拉電子基之 修飾，合成出H2BDPOMeP，H2BDPOMePOH 和H2BDPCF3P 三種配位基。 將此三種配位基去質子化後與[Ni(CH3CN)6](ClO4)2 反應得到 Ni(BDPOMeP)，Ni(BDPOMePOH)及Ni(BDPCF3P)，並在乙腈中測得其還 原電位分別為E1/2 = -0.1815/ -0.1195/ 0.017 V (vs. Fc/Fc+)。將以上三種 二價鎳錯合物氧化後，可經EPR 測得三價鎳錯合物的訊號。利用三 價鎳錯合物與KO2 反應後，可從紫外-可見光光譜圖上確認其轉變回 原本二價鎳錯合物。[Ni(H2BDPCF3P)(CH3CN)](BF4) 2 消除O2 •−的IC50 為356μM 與含其他修飾配合基的鎳錯合物比較，發現還原電位數值 越大的錯合物，其IC50 的數值也越大。Based on the ligand2,6-bis(((S)-2-(diphenyl-hydroxymethyl)-1-pyr rolidinyl)methyl)pyridine (H2BDPP) previously synthesized in our lab, this work has focused on studying the electronic effect of the ligand in the mimics of NiSOD. Three ligands H2BDPOMeP , H2BDPOMePOH and H2BDPCF3P, have been designed and synthsized. After deprotonating the ligands and reacting with [Ni(CH3CN)6](ClO4)2, three complexes Ni(BDPOMeP) (1), Ni(BDPOMePOH) (2) and Ni(BDPCF3P) (3) have been prepared. The redox potentials (E1/2) of complexes 1~3 are -0.1815, -0.1195 and 0.017 V vs. Fc/Fc+ in CH3CN, respectively. After oxiding the NiII complexs 1~3, the EPR diagrams demonstrate that they are converted to NiIII species. The electron absorption spectra indicate that reaction of 1+, 2+ and 3+ with KO2 produce original complexes 1, 2 and 3. The IC50 for scavenging O2 •− of the [Ni(H2BDPCF3P)(CH3CN)](BF4) 2 is 356μM larger than that of the [Ni(H2BDPP)(CH3)3CN](ClO4)2 and [Ni(H2BDPOMeP)(CH3)3CN](ClO4)2. Comparing the value of E1/2 and IC50 of the prepared NiSOD mimics, we find that there is a relation between the E1/2 and the IC50.