Hemoglobin-inorganic hybrid nanoflowers: Synthesis and applications for carbene N–H insertion reaction

Abstract

Hemoglobin (Hb) is a hemoprotein containing iron porphyrin, which can catalyse a variety of unnatural reactions. Due to its poor reusability and stability, in this study, we developed a new method to prepare Hb-Cu3(PO4)2 hybrid nanoflowers (HNFs) by co-incubating Hb with Cu2+. This immobilized Hb was used to catalyse the synthesis of ethyl N-phenylglycinate via the carbene N–H insertion reaction. Under the optimum reaction conditions (aniline 1 mmol; ethyl diazoacetate 1 mmol; deionized (DI) water 10 ml; catalyst (protein content: 15 mg); sodium hydrosulfite 25 mg; 25 °C; 12 h), the catalytic yield of Hb-Cu3(PO4)2 HNFs reached as high as 87% and that of free Hb was 74%. In addition, Hb-Cu3(PO4)2 HNFs can maintain a high catalytic performance after 15 cycles and still achieve yields close to 70% of the initial yield after 60 days of storage, indicating that Hb-Cu3(PO4)2 HNFs have a high potential for application in Hb-catalysed organic reactions.