Zhao Tiancong, Zhu Xiaohang, Hung Chin-Te, Wang Peiyuan, Elzatahry Ahmed, Al-Khalaf Areej Abdulkareem, Hozzein Wael N, Zhang Fan, Li Xiaomin, Zhao Dongyuan
Department of Chemistry and Laboratory of Advanced Materials, State Key Laboratory of Molecular Engineering of Polymers, Collaborative Innovation Center of Chemistry for Energy Materials (2011-iChEM) , Fudan University , Shanghai 200433 , P.R. China.
Materials Science and Technology Program, College of Arts and Sciences , Qatar University , P.O. Box 2713, Doha , Qatar.
J Am Chem Soc. 2018 Aug 8;140(31):10009-10015. doi: 10.1021/jacs.8b06127. Epub 2018 Jul 24.
Like surfactants with tunable hydrocarbon chain length, Janus nanoparticles also possess the ability to stabilize emulsions. The volume ratio between the hydrophilic and hydrophobic domains in a single Janus nanoparticle is very important for the stabilization of emulsions, which is still a great challenge. Herein, dual-mesoporous FeO@mC&mSiO Janus nanoparticles with spatial isolation of hydrophobic carbon and hydrophilic silica at the single-particle level have successfully been synthesized for the first time by using a novel surface-charge-mediated selective encapsulation approach. The obtained dual-mesoporous FeO@mC&mSiO Janus nanoparticles are made up of a pure one-dimensional mesoporous SiO nanorod with tunable length (50-400 nm), ∼100 nm wide and ∼2.7 nm mesopores and a closely connected mesoporous FeO@mC magnetic nanosphere (∼150 nm diameter, ∼10 nm mesopores). As a magnetic "solid amphiphilic surfactant", the hydrophilic/hydrophobic ratio can be precisely adjusted by varying the volume ratio between silica and carbon domains, endowing the Janus nanoparticles surfactant-like emulsion stabilization ability and recyclability under a magnetic field. Owing to the total spatial separation of carbon and silica, the Janus nanoparticles with an optimized hydrophilic/hydrophobic ratio show spectacular emulsion stabilizing ability, which is crucial for improving the biphasic catalysis efficiency. By selectively anchoring catalytic active sites into different domains, the fabricated Janus nanoparticles show outstanding performances in biphasic reduction of 4-nitroanisole with 100% conversion efficiency and 700 h high turnover frequency for biphasic cascade synthesis of cinnamic acid.
与具有可调节碳氢链长度的表面活性剂一样，Janus纳米粒子也具有稳定乳液的能力。单个Janus纳米粒子中亲水和疏水区域之间的体积比对于乳液的稳定非常重要，这仍然是一个巨大的挑战。在此，首次通过一种新颖的表面电荷介导的选择性封装方法成功合成了在单粒子水平上具有疏水碳和亲水二氧化硅空间隔离的双介孔FeO@mC&mSiO Janus纳米粒子。所获得的双介孔FeO@mC&mSiO Janus纳米粒子由长度可调（50-400 nm）、宽度约100 nm、介孔约2.7 nm的纯一维介孔SiO纳米棒和紧密连接的介孔FeO@mC磁性纳米球（直径约150 nm，介孔约10 nm）组成。作为一种磁性“固体两亲表面活性剂”，通过改变二氧化硅和碳域之间的体积比，可以精确调节亲水/疏水比，赋予Janus纳米粒子类似表面活性剂的乳液稳定能力和在磁场下的可回收性。由于碳和二氧化硅的完全空间分离，具有优化亲水/疏水比的Janus纳米粒子表现出出色的乳液稳定能力，这对于提高双相催化效率至关重要。通过将催化活性位点选择性地锚定到不同的域中，制备的Janus纳米粒子在4-硝基苯甲醚的双相还原中表现出优异的性能，转化率为100%，在肉桂酸双相级联合成中具有700 h的高周转频率。
