Five complexes of gallium derived from hydroxamic acids have been synthesised, characterised, and their anti-bacterial activity and mammalian cell toxicity established. These are three metal–organic complexes; [Ga(BPHA)₃] 1, [Ga(BHA-H)₃] 2, [Ga(SHA-H₂)(SHA-H)₃] 3, and two heteroleptic organometallic complexes [GaMe₂(BPHA)] 4, and [GaMe(BHA-H)₂] 5, along with the iron complex [Fe(BPHA)₃] 6 (BPHA-H = N-benzoyl-N-phenylhydroxamic acid, BHA-H₂ = phenylhydroxamic acid, and SHA-H₃ = salicylhydroxamic acid). Solid-state structures of 1, 4–6 were identified by single-crystal X-ray crystallography. Complexes 1 and 6 adopt an octahedral geometry at the metal centre, while the organometallic complexes 4 and 5 adopt, respectively, tetrahedral and trigonal bipyramidal geometry. The solution and solid-state chemistry of complex 3 was found to differ: the solution state is composed of an equilibrium mixture of the bis-complexed hydroximate–hydroxamate species and the homoleptic tris-hydroxamate species, with the solid state preferring the bis-complexed hydroximate–hydroxamate composition. The methyl gallium complexes 4 and 5 differed in their preferred composition with 4 forming the expected dimethyl hydroxamate complex while 5 stabilises as the methyl bis-hydroxamate complex. Complexes were tested for the anti-microbial activity against a series of Gram-positive and Gram-negative bacteria, with an emphasis on the Gram-negative Klebsiella pneumoniae. While the metal–organic complexes 1, 2, 3 and 6 showed little to no activity towards either the bacteria or mammalian cells, the alkyl gallium complexes 4 and 5 were found to have exceptional activity toward K. pneumoniae in RPMI-HS media with MIC values of 78 nM. Interestingly, [GaMe₂(OH)] also showed significant activity with an MIC of 156 nM.

中文翻译：

---

高选择性有机镓异羟肟酸盐介导的对抗生素耐药性肺炎克雷伯菌的抑制作用


已经合成、表征了五种源自异羟肟酸的镓复合物，并确定了它们的抗菌活性和哺乳动物细胞毒性。这是三种金属-有机复合物;[镓（BPHA）₃]1、[Ga（BHA-H）₃] 2、[Ga（SHA-H₂）（SHA-H）₃] 3 和两个异质有机金属络合物 [GaMe₂（BPHA）] 4 和 [GaMe（BHA-H）₂] 5，以及铁络合物 [Fe（BPHA）₃] 6 （BPHA-H = N-苯甲酰基-N-苯异肟酸，BHA-H₂ = 苯异肟酸，SHA-H₃ = 水杨异肟酸）。通过单晶 X 射线晶体学鉴定 1、4-6 的固态结构。配合物 1 和 6 在金属中心采用八面体几何形状，而有机金属配合物 4 和 5 分别采用四面体和三角双锥几何形状。发现复合物 3 的溶液和固态化学不同：溶液态由双络合异羟肟酸盐物种和同源 Tris-异羟肟酸盐物种的平衡混合物组成，固态更喜欢双络合异羟肟酸盐成分。甲基镓配合物 4 和 5 的优选组成不同，其中 4 形成预期的二甲基异羟肟酸盐络合物，而 5 稳定为双羟肟酸甲酯络合物。 测试复合物对一系列革兰氏阳性和革兰氏阴性细菌的抗菌活性，重点是革兰氏阴性肺炎克雷伯菌。虽然金属-有机复合物 1、2、3 和 6 对细菌或哺乳动物细胞几乎没有活性，但发现烷基镓复合物 4 和 5 在 MIC 值为 78 nM 的 RPMI-HS 培养基中对肺炎克雷伯菌具有特殊的活性。有趣的是，[GaMe₂（OH）] 也显示出显著的活性，MIC 为 156 nM。