Key Laboratory of Magnetic Materials and Devices, and Division of Functional Materials and Nanodevices, and New Energy Institute, Ningbo Institute of Materials Technology & Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo 315201, China.
Langmuir. 2013 Jun 25;29(25):7591-9. doi: 10.1021/la400909b. Epub 2013 Jun 14.
A new kind of analytical reagent, hexadecyl trimethyl ammonium bromide (CTAB), and dithizone product-modified gold nanoparticle dispersion, is developed for colorimetric response to 10 types of heavy metal ions (M(n+)), including Cr(VI), Cr(3+), Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), and Pb(2+). The color change of the modified gold nanoparticle dispersion is instantaneous and distinct for Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), and Pb(2+). The color change results from the multiple reasons, such as electronic transitions, cation-π interactions, formation of coordination bonds, and M(n+)-induced aggregation of gold nanoparticles (AuNPs). The different combining capacity of heavy metal ions to modifiers results in the different broadening and red-shifting of the plasmon peak of modified AuNPs. In addition, Cr(VI), Cu(2+), Co(2+), Ni(2+), and Mn(2+) cause the new UV-vis absorption peaks in the region of 360-460 nm. The interactions between the modifiers and AuNPs, and between the modifiers and M(n+), are investigated by using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results confirm that AuNPs are modified by CTAB and dithizone products through electrostatic interactions and Au-S bonds, respectively, and the M(n+)-N bonds form between M(n+) and dithizone products. Furthermore, the experimental and density functional theory calculated IR spectra prove that dithizone reacts with NaOH to produce C6H5O(-) and SCH2N4. The validation of this method is carried out by analysis of heavy metal ions in tap water.
一种新型分析试剂，十六烷基三甲基溴化铵（CTAB）和二硫腙产物修饰的金纳米粒子分散体，用于对 10 种重金属离子（M(n+)）（包括 Cr(VI)、Cr(3+)、Mn(2+)、Co(2+)、Ni(2+)、Cu(2+)、Zn(2+)、Cd(2+)、Hg(2+)和 Pb(2+)）进行比色响应。修饰后的金纳米粒子分散体的颜色变化对 Mn(2+)、Co(2+)、Ni(2+)、Cu(2+)、Zn(2+)、Cd(2+)、Hg(2+)和 Pb(2+)是瞬时且明显的。颜色变化的原因有很多，如电子跃迁、阳离子-π 相互作用、配位键的形成以及 M(n+)诱导的金纳米粒子（AuNPs）聚集。重金属离子与修饰剂的不同结合能力导致修饰后的 AuNPs 的等离子体峰的展宽和红移不同。此外，Cr(VI)、Cu(2+)、Co(2+)、Ni(2+)和 Mn(2+)在 360-460nm 区域引起新的紫外-可见吸收峰。通过傅里叶变换红外光谱和 X 射线光电子能谱研究了修饰剂与 AuNPs 之间以及修饰剂与 M(n+)之间的相互作用。结果证实，AuNPs 通过静电相互作用和 Au-S 键分别被 CTAB 和二硫腙产物修饰，并且 M(n+)和二硫腙产物之间形成 M(n+)-N 键。此外，实验和密度泛函理论计算的 IR 光谱证明二硫腙与 NaOH 反应生成 C6H5O(-)和SCH2N4。通过对自来水中重金属离子的分析验证了该方法的有效性。
