Nano Fe3O4 supported biimidazole Cu(i) complex as a retrievable catalyst for the synthesis of imidazo[1,2-a]pyridines in aqueous medium
作者:Mahmood Tajbakhsh、Maryam Farhang、Rahman Hosseinzadeh、Yaghoub Sarrafi
DOI:10.1039/c4ra03333g
日期:——
A novel magnetically recoverable nano-catalyst based on a biimidazole Cu(I) complex has been synthesized by covalent grafting of biimidazole on chloride-functionalized silica@magnetite nanoparticles, followed by metalation with CuI. The synthesized catalyst was characterized by various techniques such as CHN, NMR, FT-IR, TG/DTG, SEM, TEM, EDS, XRD, AAS, ICP-OES and VSM which revealed the superparamagnetic nature of the particles. The amount of Cu in the catalyst was measured to be 1.2 mmol g−1 by ICP-OES and AAS. From electron microscopy (SEM and TEM) studies it can be inferred that the particles are mostly spherical in shape and have an average size of 20 nm. Elemental and thermo gravimetric analysis (CHN and TG) results indicate the loading amount of functionalized organic groups on the magnetic material was 1.4 mmol g−1. The prepared nanocatalyst was shown to have excellent and green catalytic activity in the synthesis of imidazo[1,2-a]pyridines in aqueous media. The catalyst can be easily recovered by applying an external magnetic field and reused for atleast 10 times without deterioration in catalytic activity.
一种新型的可磁性回收纳米催化剂是通过将双咪唑Cu(I)络合物以共价方式接枝到氯功能化的二氧化硅@磁铁矿纳米颗粒上,并随后用CuI进行金属化而合成的。通过多种技术对合成的催化剂进行了表征,包括CHN、NMR、FT-IR、TG/DTG、SEM、TEM、EDS、XRD、AAS、ICP-OES和VSM,这些结果揭示了颗粒的超顺磁性。通过ICP-OES和AAS测得催化剂中铜的含量为1.2 mmol g−1。根据电子显微镜(SEM和TEM)研究可以推断,这些颗粒大多呈球形,平均尺寸为20 nm。元素分析和热重分析(CHN和TG)结果表明,功能化有机基团在磁性材料上的负载量为1.4 mmol g−1。所制备的纳米催化剂在水相介质中合成咪唑[1,2-a]吡啶方面表现出优异的绿色催化活性。该催化剂可以通过施加外部磁场轻松回收,并可重复使用至少10次而不降低催化活性。