NEQC: Núcleo de Estudos em Química Computacional, Department of Chemistry, Federal University of Juiz de Fora, Campus Universitário Martelos, 36.036-900 Juiz de Fora, MG, Brazil.
NQTCM: Núcleo de Química Teórica e Computacional de Macaé, Polo Ajuda, Federal University of Rio de Janeiro, Campus UFRJ-Macaé, 27.971-525 Macaé, RJ, Brazil.
J Inorg Biochem. 2019 Nov;200:110804. doi: 10.1016/j.jinorgbio.2019.110804. Epub 2019 Aug 21.
The choice of the auxiliary ligand in Au(III) complexes is of paramount importance in tuning their reactivity and biological activity. Tertiary phosphines are one of the most used auxiliary ligands in gold compounds, due to their stereo-electronic properties that confer stability and lipophilicity to these metallodrugs. The redox stability of [Au(III)(C^N^C)PR] (A) (C^N^C = 2,6-diphenylpyridine) and [Au(III)(N^N^N)PR] (N^N^N = 2,2':6',2″-terpyridine) (B) complexes (where R is the phosphine substituent groups with different steric and electronic properties) was herein investigated for a set of 41 phosphines, using the predicted standard reduction potential (ε) for Au(III)/Au(I) electrochemical system as reference. For the complexes A, ε spread over 829 mV and all values were negative, whereas for the complexes B ε were positive and covered a narrower range of 507 mV. The phosphines with high buried volume (%V ≥ 32%) decrease the complex stability despite being strong σ-donors. Both steric and electronic properties were used as molecular descriptors to build quantitative structure-property relationships (QSPR), which showed that the %V plays the major role on the redox stability of the studied Au(III) complexes. For complexes B where the phosphine affects both Au(III) and Au(I) forms, the steric impact is more pronounced on the Au(I) reduced species. The electron-donating ability of phosphines is also important and plays a greater role on the redox stability of complexes B than complexes A. These outcomes are certainly useful to predict the redox stability of Au(III) complexes which, in turn, should affect their chemical reactivity against biological targets.
辅助配体在金（III）配合物中的选择对于调节其反应性和生物活性至关重要。三膦是金化合物中最常用的辅助配体之一，由于其立体电子性质，赋予这些金属药物稳定性和亲脂性。本文研究了一系列 41 种膦配体对 [Au(III)(C^N^C)PR]（A）（C^N^C=2,6-二苯基吡啶）和 [Au(III)(N^N^N)PR]（B）（N^N^N=2,2':6',2″-三联吡啶）（B）配合物的氧化还原稳定性，使用预测的金（III）/金（I）电化学体系的标准还原电势（ε）作为参考。对于配合物 A，ε分布在 829 mV 范围内，所有值均为负值，而对于配合物 B，ε为正值，范围较窄，为 507 mV。尽管高掩埋体积的膦（%V≥32%）是强σ供体，但会降低配合物的稳定性。空间位阻和电子性质都被用作构建定量构效关系（QSPR）的分子描述符，结果表明，%V 对所研究的金（III）配合物的氧化还原稳定性起主要作用。对于膦同时影响金（III）和金（I）形式的配合物 B，空间位阻对还原的金（I）物种的影响更为明显。膦的供电子能力也很重要，对配合物 B 的氧化还原稳定性的影响大于配合物 A。这些结果对于预测金（III）配合物的氧化还原稳定性肯定是有用的，这反过来又会影响它们对生物靶标的化学反应性。
