CW and Pulsed ESR Spectroscopy of Cupric Ions in the Metal-Organic Framework Compound Cu3(BTC)2
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- 作者：Andreas Pö ; ppl ; Sebastian Kunz ; Dieter Himsl ; Martin Hartmann
- 刊名：Journal of Physical Chemistry C
- 出版年：2008
- 出版时间：February 21, 2008
- 年：2008
- 卷：112
- 期：7
- 页码：2678 - 2684
- 全文大小：196K
- 年卷期：v.112,no.7(February 21, 2008)
- ISSN：1932-7455
文摘
The metal-organic framework (MOF) compound Cu3(BTC)2(H2O)3·xH2O (BTC = benzene 1,3,5-tricarboxylate) was prepared by solvothermal synthesis under ambient pressure and structurally characterized bypowder X-ray diffraction and nitrogen adsorption at 77 K. X- and Q-band CW electron spin resonance andhyperfine sublevel correlation spectroscopies were used to explore the coordination state and location of theCu(II) ions in the porous coordination polymer. Cupric ions were found to be present in two different chemicalenvironments: (a) Cu(II)2 clusters in the paddle-wheel building blocks of the Cu3(BTC)2 network, giving riseto an antiferromagnetically coupled spin state in accordance with previous susceptibility measurements(J. Appl. Phys. 2000, 87, 6007). However, the cross-linking of the paddle wheels by the BTC linker leads toan additional spin exchange among dimers as evidenced by the characteristics of the S = 1 ESR signal oftheir excited spin state. (b) In addition, paramagnetic monomer Cu(II) species are accommodated in the poresystem of Cu3(BTC)2. They coordinate to adsorbed water molecules and form [Cu(H2O)6]2+ complexes, whichare inhomogeneously distributed over the Cu3(BTC)2 pore system.