تهيه نانوكاتاليست مغناطيسي ناهمگن برپايه گرافن اكسيد كاهش يافته با ذره‌هاي نيكل و كبالت و بررسي فعاليت آن درواكنش‌هاي جفت‌شدن هك، سونوگاشيرا و احياي 4- نيتروفنل

Preparation of heterogeneous magnetic nanocatalysts based on reduced graphene oxide with nickel and cobalt particles and investigation of its activity in Heck and sonogashira cross-coupling reactions and 4-nitrophenol reduction

در اين پژوهش، نانوذره­ هاي فلزي نيكل و كبالت به روش تك­ ظرفي و سبز بر روي بستر گرافن اكسيد تهيه و با روش هاي طيف شناسي فروسرخ تبديل فوريه (FTIR)، ميكروسكوپي الكتروني پويشي گسيل ميداني (FESEM)، پراش پرتو ايكس (XRD) و مغناطيس سنجي نمونه ارتعاشي (VSM) شناسايي و كارايي آن در واكنش­ كاهش 4-نيتروفنل، واكنش ­هاي جفت­ شدن هك و سونوگاشيرا بررسي شد. درصد تبديل واكنش دهنده ­ها با به كارگيري طيف شناسي فرابنفش-مرئي (UV-Vis) و سوانگاري گازي (GC) محاسبه شد. نتيجه ­ها نشان داد كه ذره ­هاي مغناطيسي نيكل و كبالت با اندازه در حدود 20 تا 40 نانومتر به­ طور­ يكنواخت بر نانوصفحه هاي گرافن ­اكسيد قرارگرفته و واكنش ­هاي آلي تحت تاثير كاتاليست حاوي نيكل وكبالت در شرايط بهينه با بازده بالا قابل انجام است. با توجه به رفتار فرومغناطيس اين نانوكاتاليست­ ها، قابليت جداشدن و چندين مرتبه استفاده را داشتند و درنتيجه مي ­توان از آن به عنوان يك كاتاليست مطمئن و موثر در واكنش­ هاي جفت شدن آلي بهره برد.

Today catalysts are widely used in the production of various materials. Nano-catalysts according to their importance have become one of the most important areas for Nanotechnology research. Development of magnetic catalysts for carbon–carbon and carbon–heteroatom coupling reactions are one of the most important issues in terms of applications to organic synthesis. At present, many researches are focused on the construction of more active and more stable, heterogeneous Nano-sized metal catalysts, which can be recovered and reused. Nickel and cobalt nanoparticles due to low prices, magnetic properties and high chemical activity attracted particular attention. In this work, nickel and cobalt nanoparticles were synthesized with a green and one-pot method on graphene oxide substrate for reduction reaction of 4-nitrophenol, Heck and Sonogashira cross-coupling reactions. Several characterization techniques such as FTIR, FESEM, XRD, and VSM were employed to characterize the Co and Ni nanoparticle reduced graphene oxide composites witch indicates that nickel and cobalt magnetic particles with a size of about 20-30 nanometers were uniformly anchored on graphene oxide nanosheets. In addition, results showed that incorporation of Co and Ni nanoparticles and GO produce much higher activity in cross-coupling and reduction reactions. The soft-ferromagnetic behavior of the RGO/CoxNi100-x nanocomposite demonstrated the easy separable from the reaction mixture and reusable several times without losing its catalytic activity, Hence, the RGO/CoxNi100-x composites can be a potential promising material to catalyze the cross-coupling reactions.