Chemistry Department, Astrakhan State Technical University, 16 Tatisheva Str., 414056 Astrakhan, Russia.
N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia.
Int J Mol Sci. 2024 Aug 19;25(16):9011. doi: 10.3390/ijms25169011.
A series of novel organogermanium(IV) catecholates - of the general formula R'Ge(Cat), where R' = Ph, Et, have been synthesized. Compounds were characterized by H, C NMR, IR spectroscopy, and elemental analysis. The molecular structures of -, , and in crystal state were established using single-crystal X-ray analysis. The complexes are tetracoordinate germanium(IV) compounds containing a dioxolene ligand in a dianion (catecholato) form. Electrochemical transformations of target germanium(IV) complexes have been studied by cyclic voltammetry. The electro-oxidation mechanism of complexes -, , and (the related complex PhGe(3,5-Cat) where 3,5-Cat is 3,5-di--butylcatecholate) involves the consecutive formation of mono- and dicationic derivatives containing the oxidized forms of redox-active ligands. The stability of the generated monocations depends both on the hydrocarbon groups at the germanium atom and on the substituents in the catecholate ring. Compounds , , and are oxidized irreversibly under the electrochemical conditions with the formation of unstable complexes. The radical scavenging activity and antioxidant properties of new complexes were estimated in the reaction with DPPH radical, ABTS radical cation, and CUPRAC assay. It has been found that compounds and with benzothiazole or phenol fragments are more active in DPPH test. The presence of electron-rich moieties in the catecholate ligand makes complexes and - more reactive to ABTS radical cation. The value of CUPRAC for organogermanium(IV) catecholates varies from 0.23 to 1.45. The effect of compounds - in the process of lipid peroxidation of rat liver (Wistar) homogenate was determined in vitro. It was found that most compounds are characterized by pronounced antioxidant activity. A feature of complexes , , and - is the intensification of the antioxidant action with the incubation time. In the presence of additives of complexes , , , and , an induction period was observed during the process of lipid peroxidation.
一系列新型有机锗(IV)邻苯二酚配合物 - 通式为 R'Ge(Cat)，其中 R' = Ph，Et，已被合成。化合物通过 H、C NMR、IR 光谱和元素分析进行了表征。通过单晶 X 射线分析确定了 - 、 - 和 - 在晶体状态下的分子结构。这些配合物是四配位的锗(IV)化合物，含有二氧戊环配体的二阴离子（邻苯二酚）形式。通过循环伏安法研究了目标锗(IV)配合物的电化学转化。配合物 - 、 - 和 -（相关的配合物 PhGe(3,5-Cat)，其中 3,5-Cat 是 3,5-二叔丁基邻苯二酚）的电氧化机制涉及到单离子和二阳离子衍生物的连续形成，其中包含氧化形式的氧化还原活性配体。生成的单阳离子的稳定性既取决于锗原子上的烃基，也取决于邻苯二酚环上的取代基。在电化学条件下，化合物 - 、 - 和 - 不可逆地被氧化，形成不稳定的配合物。用 DPPH 自由基、ABTS 自由基阳离子和 CUPRAC 测定法评估了新配合物的自由基清除活性和抗氧化性质。结果发现，具有苯并噻唑或苯酚片段的化合物 - 和 - 在 DPPH 试验中更具活性。邻苯二酚配体中富电子部分的存在使配合物 - 和 - 对 ABTS 自由基阳离子更具反应性。有机锗(IV)邻苯二酚配合物的 CUPRAC 值在 0.23 到 1.45 之间变化。在体外，测定了化合物 - 在大鼠肝（Wistar）匀浆的脂质过氧化过程中的作用。结果发现，大多数化合物表现出明显的抗氧化活性。配合物 - 、 - 和 - 的一个特点是，随着孵育时间的延长，抗氧化作用增强。在配合物 - 、 - 、 - 和 - 的添加剂存在下，观察到脂质过氧化过程中的诱导期。
