Kumar Rakesh, Maji Anweshika, Biswas Bhargab, Draksharapu Apparao
Southern Laboratories - 208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
Dalton Trans. 2024 Mar 19;53(12):5401-5406. doi: 10.1039/d3dt03747a.
In copper-based enzymes, Cu-hydroperoxo/alkylperoxo species are proposed as key intermediates for their biological activity. A vast amount of literature is available on the functional and structural mimics of enzymatic systems with heme and non-heme ligand frameworks to stabilize high valent metal intermediates, mostly at low temperatures. Herein, we report a reaction between [Cu(NCCH)] and -chloroperoxybenzoic acid (CPBA) in CHCN that produces a putative Cu(CPBA) species (1). 1 was characterized by UV/Vis, resonance Raman, and EPR spectroscopies. 1 can catalyze both electrophilic and nucleophilic reactions, demonstrating its amphoteric behavior. Additionally, 1 can also conduct electron transfer reactions with a weak reducing agent such as diacetyl ferrocene, making it one of the reactive copper-based intermediates. One of the most important aspects of the current work is the easy synthesis of a Cu(CPBA) adduct with no complicated ligands for stabilization. Over time, 1 decays to form a Cu paddle wheel complex (2) and is found to be unreactive towards substrate oxidation.
在铜基酶中，铜-氢过氧/烷基过氧物种被认为是其生物活性的关键中间体。关于具有血红素和非血红素配体框架的酶系统的功能和结构模拟物以稳定高价金属中间体的文献大量存在，这些研究大多是在低温下进行的。在此，我们报道了[Cu(NCCH)]与氯过氧苯甲酸（CPBA）在乙腈中的反应，该反应生成了一种假定的Cu(CPBA)物种（1）。通过紫外可见光谱、共振拉曼光谱和电子顺磁共振光谱对1进行了表征。1既能催化亲电反应，也能催化亲核反应，显示出其两性行为。此外，1还能与弱还原剂如二乙酰二茂铁发生电子转移反应，使其成为活性铜基中间体之一。当前工作最重要的方面之一是易于合成一种不含用于稳定化的复杂配体的Cu(CPBA)加合物。随着时间的推移，1会分解形成一种铜桨轮配合物（2），并且发现其对底物氧化无反应活性。
