In this paper, we have synthesized surface active ionic liquid (SAIL)-capped zinc sulfide (ZnS) quantum dots (QDs) with an average size of approximately 3.03 nm using a systematic and facile microwave-irradiation method in aqueous solution. The imidazolium-based SAIL, 1-dodecyl-3-ethylimidazolium bromide was acted as a capping agent and was found to modulate the morphology and properties of ZnS QDs. The synthesized ZnS QDs were examined via different techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL) and cyclic voltammetry (CV). TGA confirmed the thermal stability of capped ZnS QDs. To investigate the fluorometric application, the synthesized ZnS quantum dots were tested for the sensing of ascorbic acid (AA). The fluorescence intensity was found to be directly proportional to the concentration of AA in the range of 50–476 µM and the limit of detection was 63.11 µM. It has been observed that the synthesized capped ZnS QDs selectively sense AA and calculated limit of detection (LOD) of AA was found to be lower than that of other reported systems using the fluorescence technique. To understand the role of capping agent in the synthesis of ZnS QDs, density functional theory (DFT) using B3LYP (Becke’s three-parameter exchange functional with Lee–Yang–Parr correlation energy) and 6-311 + G (d, p) basis set was employed. The DFT results showed that the SAIL played a vital role in the size-controlled synthesis of ZnS QDs.

在本文中，我们使用系统简便的水溶液辐照方法合成了平均表面尺寸约为3.03 nm的表面活性离子液体（SAIL）封端的硫化锌（ZnS）量子点（QDs）。基于咪唑鎓的SAIL 1-十二烷基-3-乙基咪唑鎓溴化物用作封端剂，并发现其可调节ZnS QD的形貌和性能。合成的ZnS量子点通过不同的技术进行了检查，例如X射线衍射（XRD），扫描电子显微镜（SEM）和能量色散X射线分析（EDAX），透射电子显微镜（TEM），傅立叶变换红外光谱（FT） -IR），热重分析（TGA），漫反射光谱（DRS），光致发光光谱（PL）和循环伏安法（CV）。TGA证实了封端的ZnS QD的热稳定性。为了研究荧光应用，对合成的ZnS量子点进行了抗坏血酸（AA）感测测试。发现荧光强度与AA浓度成正比，范围在50–476 µM之间，检出限为63.11 µM。已经观察到，合成的封端的ZnS QD选择性地感测AA，并且发现AA的计算检出限（LOD）低于使用荧光技术的其他报道的系统。要了解封端剂在合成ZnS QD中的作用，请使用B3LYP（具有Lee-Yang-Parr相关能的贝克尔三参数交换函数）和6-311 + G（d，p）的密度泛函理论（DFT）聘用。