Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Victoria 3086, Australia.
Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Victoria 3086, Australia.
Dalton Trans. 2020 Sep 22;49(36):12820-12834. doi: 10.1039/d0dt02225j.
A post-synthetic modification and metallation procedure has been used to prepare a family of heterobimetallic Au(i)-Ag(i) and Au(i)-Hg(ii) complexes featuring either symmetrical or asymmetrical bis-N-heterocyclic carbene ligands with methylene or ethylene linker groups. This synthetic approach is versatile and allows for the synthesis of heterobimetallic complexes bearing asymmetrical ligands that differ in the nature of the NHC wingtip substituents (dimethyl, diethyl or ethyl-methyl) and for the selective placement of the different metal ions. The synthesised complexes were characterised using 1H and 13C NMR spectroscopy and high resolution mass spectrometry (HR-MS) and in the case of complexes 4a, 5b and 8b by X-ray crystallography. The complexes of the methylene linked bridging ligands display conformational isomerism in solution and the conformations adopted by selected compounds were examined using variable temperature (VT) 1H NMR studies. The antibacterial properties of the heterobimetallic Au(i)-Ag(i) complexes in addition to the corresponding homobimetallic Ag(i)2, Au(i)2 complexes were evaluated against clinically relevant Gram-positive and Gram-negative bacterial strains. The homobimetallic Au(i)2 complex and precursor pro-ligand displayed no antibacterial activity up to 256 μg mL-1, whereas the homobimetallic Ag(i)2 was active against all Gram-positive and Gram-negative bacterial strains tested (MIC = 8-32 μg mL-1). Interestingly, both Au(i)-Ag(i) heterobimetallic complexes displayed similar broad-spectrum activity (MIC = 4-32 μg mL-1) to the Ag(i)2 homobimetallic complex.
已经采用后合成修饰和金属化程序来制备一系列具有对称或不对称双 N-杂环卡宾配体的异双金属 Au(i)-Ag(i)和 Au(i)-Hg(ii)配合物，这些配体带有亚甲基或亚乙基连接基团。这种合成方法具有通用性，可以合成具有不对称配体的异双金属配合物，这些配体在 NHC 翼端取代基的性质（二甲基、二乙基或乙基-甲基）和不同金属离子的选择性位置上有所不同。所合成的配合物使用 1H 和 13C NMR 光谱以及高分辨率质谱 (HR-MS) 进行了表征，对于配合物 4a、5b 和 8b 还通过 X 射线晶体学进行了表征。亚甲基桥连配体的配合物在溶液中显示构象异构，使用变温（VT）1H NMR 研究考察了选定化合物所采用的构象。除了相应的同双金属 Ag(i)2、Au(i)2 配合物外，还评估了异双金属 Au(i)-Ag(i)配合物的抗菌性质对临床相关革兰氏阳性和革兰氏阴性细菌菌株的影响。同双金属 Au(i)2 配合物和前体预配体在高达 256 μg mL-1 的浓度下没有显示出抗菌活性，而同双金属 Ag(i)2 对所有测试的革兰氏阳性和革兰氏阴性细菌菌株都具有活性（MIC = 8-32 μg mL-1）。有趣的是，两种 Au(i)-Ag(i)异双金属配合物都显示出与 Ag(i)2 同双金属配合物相似的广谱活性（MIC = 4-32 μg mL-1）。
