【作者】 张宝华；

【导师】 吴芳英；

【作者基本信息】 南昌大学 ， 应用化学， 2010， 硕士

【摘要】 分子识别是超分子化学研究的核心内容之一,它包括对中性分子、阳离子和阴离子的识别。由于无机离子在生物催化、生命科学、电子与信号的传递、环境保护等方面起着重要作用,因此建立高灵敏和高选择性、操作简便且成本低廉的识别离子新方法十分必要。量子点作为一种新型的荧光探针颇受关注,将其表面进行功能化,可有效改善识别客体离子的灵敏度和选择性,建立不同离子的荧光传感器。相关领域的研究已经引起了科研工作者的广泛关注。本论文分为五部分,介绍量子点作为荧光探针用于识别分子的发展状况、各类分子光化学传感体系及相关的作用机理,详细阐述了本论文所提出的各类离子传感新体系。第一章简要介绍量子点的概念及组成体系、光学性质及发光优势、制备方法的发展进程、特殊功能化修饰及在化学传感器方面的应用,对近几年来国内外相关研究成果进行了简要评述。第二章以巯基乙酸为稳定剂,在常温常压下合成了Mn掺杂ZnS的半导体纳米晶(ZnS:Mn2+),利用红外光谱、X-射线衍射谱(XRD)、荧光光谱、紫外可见吸收光谱和粒度分布曲线等手段对纳米晶进行了结构表征。结果表明：该纳米晶呈现闪锌矿结构,粒径小而均匀,表面修饰有巯基乙酸分子后具有良好的水溶性。在室温下,硫离子(S2-)的存在使纳米溶胶体系的荧光产生显著的猝灭现象,而其它阴离子如：NO3-、CH3COO-、CO32-、Br-、F-、NO2-、SO42-、S2O32-、I-、SO32-等在一定浓度范围内不干扰S2-的测定,据此建立了水相中识别S2-的新体系。实验结果显示：纳米溶胶在590 nm处发光强度的变化与S2-浓度(在2.5-37.5μmol·L-1范围内)呈良好的线性关系,方法检测下限为1.5×10-7 mol·L-用于废水中S2-的测定,其回收率为103%。第三章采用与第二章相似的方法,以巯基乙酸为表面修饰剂制备了未经陈化的Mn掺杂ZnS量子点(ZnS:Mn2+)应用于金属镉离子(Cd2＋)的识别。在pH 7.7的Tris-HCl缓冲介质中,Cd2+的加入能有效地增强体系发光,同时荧光强度的增量与Cd2+浓度呈良好的线性关系,其线性范围为5.0×10-7-8.9×10-5mol·L-1,方法检测下限为3.08×10-8 mol·L-1。该方法用于湖水中Cd2+的检测,回收率为93.7-97.4%。同时利用荧光光谱、紫外可见吸收光谱及XRD谱研究了ZnS:Mn2+量子点结构特点和发光性能,并对可能机理进行了初步探讨。第四章利用硼氢化钠将牛血清白蛋白(BSA)的二硫键还原,将其修饰于ZnS:Mn2+量子点表面,以提高量子点的发光效率和稳定性。在优化实验条件下,Cu2+对ZnS:Mn2+-BSA体系的荧光具有强烈猝灭作用,据此建立了测定Cu2+的新方法,其线性范围为2.0×10-6-7.8×10-5 mol·L-1线性校正方程为F0/F=1.01+0.06 CCu2+,方法检测下限为2.87×10-7 mol·L-1,应用于自来水中Cu2+的测定,回收率为98.8%。第五章通过二硫化碳(CS2)将亚氨基二乙酸零距离修饰于ZnS:Mn2+/ZnS核壳结构半导体纳米晶表面上,该修饰不仅解决了纳米晶水溶性问题,而且使纳米晶本身在590 nm处橙黄色发光增强且稳定性提高。以紫外可见吸收光谱、荧光光谱、电感耦合等离子体-发射光谱(ICP-AES)、粒度分布曲线及核磁共振谱为手段对合成的纳米晶进行了结构表征。在优化的实验条件下,发现Ag+能够非常灵敏地使体系荧光发生明显猝灭,而其它离子无显著干扰,表现出良好的选择性。紫外可见吸收光谱结果表明：Ag+与纳米晶表面的配体形成了稳定的配合物,在光诱导下发生了电子转移,导致了荧光信号猝灭。更多还原

【Abstract】 Molecular recognition is an important area of supramolecular chemistry, which includes sensing of neutral molecular, cations and anions. The recognition and sensing of anions and cations have received considerable attention for their important roles in biological, industrial and environmental process. As a new type of fluorescent sensors, quantum dot (QDs) offer a number of attractive features, including high photobleaching threshold, good chemical stability, narrow and symmetric luminescence bands, which are expected to remedy the deficiencies of the organic dyes. In the thesis, several highly selective and sensitive sensors for anions or cations were constructed. The sensors (modified QDs) were characterized, and the assays for sensing sulfide anion, cadium (Ⅱ) ion, cupper (Ⅱ) ion and silver (Ⅰ) ion were introduced.In Chapter 1, the concept, the nature and the preparation methods development of quantum dots were briefly reviewed. Then the special functional and chemical sensors are emphatically introduced.In Chapter 2, water-soluble Mn2+-doped ZnS quantum dots (QDs) were prepared using mercaptoacetic acid as the stabilizer. The optical properties and structure features were characterized by X-Ray diffraction, absorption spectrum, IR spectrum and fluorescence spectrum. In pH 7.8 Tris-HCl buffer, the QDs emitted strong fluorescence peaked at 590 nm with excitation wavelength at 300 nm. The presence of sulfide anion resulted in the quenching of fluorescence and the intensity decrease was proportional to the S2- concentration. The linear range was from 2.5×10-6 to 3.8×10-5 mol L-1. Most anions such as F-, Cl-, Br-, I-, CH3CO2-, ClO4-, CO32-, NO2-, NO3-, S2O32-, SO32- and SO42- did not interfere with the determination. A highly selective assay was introduced and applied to determine S2- in discharged water with recovery of ca.103%.In Chapter 3, ZnS:Mn2+quantum dots with good dispersity and fluorescent characteristics were synthesized in aqueous solution with thioglycolic acid as a stabilizing agent, which were proposed for the determination of cadmium ions (Ⅱ). In the Tris-HCl buffer with pH 7.7, it was found that the fluorescent intensity of thiol-capped ZnS:Mn2+ was enhanced by the presence of Cd2+. The fluorescence intensity of ZnS:Mn2+ increased linearly with the concentration of Cd2+ in the rang of 5.0×10-7-8.9×10-5 mol·L-1. The detection limit was 3.08×10-8 mol·L-1. This method was used to the determination of Cd2+ in discharged water, and the recovery was 93.7-97.4%. The properties of above ZnS:Mn2+ quantum dots were studied by the fluorescence spectra, UV-vis absorption spectra and X-ray diffraction(XRD). The possible mechanism was discussed as well.In Chapter 4, ZnS:Mn2+ quantum dots with peculiar spectral properties were synthesized in an aqueous solution using thioglycolic acid as a stabilizing agent. To improve their fluorescence properities in water solution, bovine serum albumin (BSA) was absorbed on their surface. Under the optimal conditions, the fluorescence intensity of the ZnS:Mn2+ decreased linearly with the concentration of copper(II) ions in the rang of 2×10-6-7.8×10-5 mol·L-1. The liner calibration equation was following: Fo/F= 1.01+0.06 CCu2+ and the detection limit was 2.87×10-7 mol×L-1. The proposed method was successfully applied to determine copper (Ⅱ) ions in tap water samples with recovery of ca.98.8%.In Chapter 5, the probe consisted of fluorescent ZnS:Mn2+/ZnS core/shell quantum dots (QDs) were properly conjugated to iminodiacetic acid through CS2-assisted zero-length covalent coupling. The functionalized nanoparticles not only improve water-soluble, but also exhibit a strong fluorescent emission at ca.590 nm. Their optical and structural properties have been characterized by UV-vis spectroscopy, fluorescent spectroscopy and 1H NMR spectroscopy. In pH 7.3 phosphate buffer, the calibration plot between intensity ratio (Fo/F) and the concentration of Ag+ was linear in the range of 1.5-10.5×10-6 mol·L-1 with correlation coefficient of 0.992. The limit of detection was 2.65×10-7 mol·L-1. The effect of the other ions (including alkali metal ions, alkali earth metal ions, Pb2+, Cd2+, Zn2+, Ba2+ Al3+, Ca2+, Mg2+, Na+, K+ and anions such as NO3-, SO42-, CO32- was negligible even at a very high concentration. The possible mechanism was proposed.更多还原