Probing Conformation Change and Binding Mode of Metal Ion-Carboxyl Coordination Complex through Resonant Surface-Enhanced Raman Spectroscopy and Density Functional Theory
Probing Conformation Change and Binding Mode of Metal Ion-Carboxyl Coordination Complex through Resonant Surface-Enhanced Raman Spectroscopy and Density Functional Theory
复制标题
通过共振表面增强拉曼光谱和密度泛函理论探讨金属离子-羧基配位配合物的构象变化和结合模式
DOI：
10.1021/acs.jpclett.9b01435
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发表时间：
2019-08-15
影响因子：
5.7
通讯作者：
Lei, Dangyuan
中科院分区：
文献类型：
--
作者：
Ho, Willis Kwun Hei;Bao, Zhi Yong;Lei, Dangyuan
了解羧基与金属配体的相互作用在分析化学中具有重要意义。在这里，我们使用共振表面增强拉曼散射(SERS)来探测吸附在等离子体共振金属纳米结构表面的几种金属离子羧基配位体系的物理化学相互作用和构象变化。我们的SERS结果和密度泛函理论计算共同表明，低价金属离子(如K+和Pb2+)倾向于以低结合能的单齿结合方式与拉曼标记分子4-MBA的羧基结合，而高价金属离子(如Fe3+)倾向于以较高结合能的双齿结合方式结合。特别是，依赖于Pb2+离子浓度的SERS表明，配位络合物之间存在排斥作用，导致4-MBA在金属表面形成倾斜的构型。这项工作表明，共振SERS方法不仅适用于研究羧基与金属配体的相互作用，而且适用于检测各种低浓度的重金属离子。
Understanding carboxyl-metal ligand interaction has great significance in analytical chemistry. Herein, we use resonant surface-enhanced Raman scattering (SERS) to probe the physiochemical interaction and conformation change in several metal ion carboxyl coordination complex systems adsorbed on the surface of plasmonically resonant metal nanostructures. Our SERS results and density function theory calculations jointly reveal that low-valence metal ions (such as K+ and Pb2+) tend to bind to the carboxyl active site of a Raman tag molecule, 4-mercaptobenzoic acid (4-MBA), in a unidentate binding mode of low binding energy whereas high-valence metal ions (such as Fe3+) favor a bidentate binding mode of relatively high binding energy. Particularly, Pb2+-ion concentration-dependent SERS suggests a repulsive interaction among the coordination complex leading to a tilted configuration of 4-MBA on the metal surface. This work indicates the resonant SERS approach is suitable not only for studying the carboxyl-metal ligand interaction but also for detecting various types of heavy metal ions at low concentrations.