Thawarkar Sachin, Nirmale Trupti C, More Sahebrao, Ambekar Jalindar D, Kale Bharat B, Khupse Nageshwar D
Physical and Material Chemistry Division , CSIR-National Chemical Laboratory , Pune 411008 , India.
Centre for Materials for Electronic Technology , Dr Homi Bhabha Road, Panchawati , Pune 411008 , India.
Langmuir. 2019 Jul 16;35(28):9213-9218. doi: 10.1021/acs.langmuir.9b01223. Epub 2019 Jul 2.
In this work, a fresh approach has been proposed for the efficient transfer of gold nanoparticles (AuNPs) from an aqueous to organic phase by the metathesis reaction or anion exchange reaction. Here, we synthesized ionic liquid 1-butyl 3-hexadecyl imidazolium bromide [CCIm]Br-stabilized AuNPs which exhibit excellent stability in solution. Transfer of Au@[CCIm]Br from an aqueous to organic phase was investigated by the metathesis reaction with different hydrophobic ionic liquid-forming salts such as LiNTf, LiClO, and KPF. The anionic exchange process in ionic liquids at the AuNP surface to make hydrophilic to hydrophobic AuNPs is demonstrated. It was found that hydrophobic ionic liquids provide the most effective transfer of AuNPs from the aqueous to organic phase. Interestingly, we have noticed no change in color, size, and shape of AuNPs for more than a month, indicating more efficient transfer of AuNPs in organic solvents, which remained stable for over a month. The ionic liquids with anions NTf, ClO, and PF make the AuNP surface hydrophobic, indicating their good dispersibility in nonpolar solvents. Finally, these AuNPs exhibit excellent sensitivity toward the refractive index of organic solvents, which is correlated with the surface plasmon resonance (SPR) λ bands.
在这项工作中，提出了一种通过复分解反应或阴离子交换反应将金纳米颗粒（AuNPs）从水相高效转移到有机相的新方法。在此，我们合成了离子液体1-丁基-3-十六烷基溴化咪唑鎓[CCIm]Br稳定的AuNPs，其在溶液中表现出优异的稳定性。通过与不同的疏水性离子液体形成盐（如LiNTf、LiClO和KPF）的复分解反应，研究了Au@[CCIm]Br从水相到有机相的转移。证明了离子液体中AuNP表面的阴离子交换过程，使亲水性的AuNPs变为疏水性。结果发现，疏水性离子液体能最有效地将AuNPs从水相转移到有机相。有趣的是，我们注意到AuNPs的颜色、尺寸和形状在一个多月内没有变化，这表明AuNPs在有机溶剂中的转移效率更高，并且在一个多月内保持稳定。含有NTf、ClO和PF阴离子的离子液体使AuNP表面具有疏水性，表明它们在非极性溶剂中具有良好的分散性。最后，这些AuNPs对有机溶剂的折射率表现出优异的灵敏度，这与表面等离子体共振（SPR）λ带相关。
