Metavarayuth Kamolrat, Ejegbavwo Otega, McCarver Gavin, Myrick Michael L, Makris Thomas M, Vogiatzis Konstantinos D, Senanayake Sanjaya D, Manley Olivia M, Ebrahim Amani M, Frenkel Anatoly I, Hwang Sooyeon, Rajeshkumar Thayalan, Jimenez Juan D, Chen Kexun, Shustova Natalia B, Chen Donna A
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States.
Department of Chemistry, University of Tennessee Knoxville, Knoxville, Tennessee 37996, United States.
J Phys Chem Lett. 2020 Oct 1;11(19):8138-8144. doi: 10.1021/acs.jpclett.0c02539. Epub 2020 Sep 15.
Raman spectroscopy was used to establish direct evidence of heterometallic metal centers in a metal-organic framework (MOF). The Cu(BTC) MOF HKUST-1 (BTC = benzenetricarboxylate) was transmetalated by heating it in a solution of RhCl to substitute Rh ions for Cu ions in the dinuclear paddlewheel nodes of the framework. In addition to the Cu-Cu and Rh-Rh stretching modes, Raman spectra of (CuRh)(BTC) show the Cu-Rh stretching mode, indicating that mixed-metal Cu-Rh nodes are formed after transmetalation. Density functional theory studies confirmed the assignment of a Raman peak at 285 cm to the Cu-Rh stretching vibration. Electron paramagnetic resonance spectroscopy experiments further supported the conclusion that Rh ions are substituted into the paddlewheel nodes of Cu(BTC) to form an isostructural heterometallic MOF, and electron microscopy studies showed that Rh and Cu are homogeneously distributed in (CuRh)(BTC) on the nanoscale.
拉曼光谱被用于建立金属有机框架（MOF）中异金属中心的直接证据。通过在RhCl溶液中加热Cu(BTC) MOF HKUST-1（BTC = 苯三甲酸酯）进行金属转移，用Rh离子取代框架双核桨轮节点中的Cu离子。除了Cu-Cu和Rh-Rh伸缩模式外，(CuRh)(BTC)的拉曼光谱显示出Cu-Rh伸缩模式，表明金属转移后形成了混合金属Cu-Rh节点。密度泛函理论研究证实了285 cm处的拉曼峰归属于Cu-Rh伸缩振动。电子顺磁共振光谱实验进一步支持了Rh离子被取代进入Cu(BTC)的桨轮节点以形成同构异金属MOF的结论，并且电子显微镜研究表明Rh和Cu在纳米尺度上均匀分布于(CuRh)(BTC)中。
