Abstract：
In this work, L-Histidine-protected copper nanoclusters synthesized by changing the pH levels of precursor solution have been shown to display different emission wavelengths and intensities. As determined by mass spectrometry, nanoclusters Cu3L2 synthesized at acidic pH have 3 atoms in their core and emit in the greenish-yellow region, and nanoclusters Cu2L2, synthesized in the basic conditions have 2 atoms in their core and emit in the blue-green region. They are expected to have coordination through the carboxylate group and nitrogen of the imidazole ring of histidine ligand, respectively. Metal ions Mg2+, Mn2+, Zn2+, and Pb2+ selectively enhance the interaction between carboxylate - copper metal core and increase the emission intensity of Cu3L2. These metal ions weaken the interaction between imidazole nitrogen and copper metal core and quench the emission intensity of Cu2L2. As synthesized, nanoclusters exhibit good water solubility and photostability, they can act as fluorescent probes to sense the metal ions, therefore, they were utilized for the optical sensing of the mentioned metal ions. Fluorescent nanoclusters were found to sense even a very low concentration of metal ions with a limit of detection (3 σ/slope) in nanomolar range.
摘要：
在这项工作中,通过改变前体溶液的pH水平合成的L-组氨酸保护的铜纳米簇已经显示出显示不同的发射波长和强度。通过质谱法测定,在酸性pH下合成的纳米团簇Cu3L2在其核心中有3个原子，并在黄绿色区域发射，在碱性条件下合成的Cu2L2和纳米团簇在其核心中有2个原子，并在蓝绿色区域发射。它们有望通过组氨酸配体的咪唑环的羧基和氮进行配位，分别。金属离子Mg2+,Mn2+,Zn2+,和Pb2选择性地增强了羧酸盐-铜金属核之间的相互作用，并增加了Cu3L2的发射强度。这些金属离子削弱了咪唑氮与铜金属核之间的相互作用，并猝灭了Cu2L2的发光强度。作为合成，纳米团簇表现出良好的水溶性和光稳定性，它们可以作为荧光探针来检测金属离子，因此,它们被用于所述金属离子的光学感测。发现荧光纳米团簇甚至可以感测到非常低浓度的金属离子，其检测极限（3σ/斜率）在纳摩尔范围内。
