Institute of Functional Interfaces (IFG) and ‡Institute for Nanotechnology (INT), Karlsruhe Institute of Technology , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
ACS Appl Mater Interfaces. 2017 Oct 25;9(42):37463-37467. doi: 10.1021/acsami.7b12045. Epub 2017 Oct 16.
As in the case of other semiconducting materials, optical and electronic properties of metal-organic frameworks (MOFs) depend critically on defect densities and defect types. We demonstrate here that, in addition to the influence of imperfections on MOF chemical properties like guest binding energies and catalytic activity, the optical properties of these crystalline molecular solids also crucially depend on deviations from the perfect crystalline structure. By recording UV-vis absorption spectra for MOF thin films of particularly high quality, we demonstrate that low-defect samples of an important MOF, HKUST-1, are virtually colorless. Electronic structure calculations of the excited states by employing complete active space self-consistent field (CASSCF) calculations show that the d-d excitations in defects result in the typical green color of the MOF material synthesized by conventional methods.
与其他半导体材料一样，金属有机骨架（MOF）的光学和电子性质严重依赖于缺陷密度和缺陷类型。在这里，我们证明了除了不完善对 MOF 化学性质（如客体结合能和催化活性）的影响外，这些晶体分子固体的光学性质也严重依赖于与完美晶体结构的偏差。通过记录特别高质量的 MOF 薄膜的紫外可见吸收光谱，我们证明了重要的 MOF，HKUST-1 的低缺陷样品实际上是无色的。通过采用完全活性空间自洽场（CASSCF）计算的激发态电子结构计算表明，缺陷中的 d-d 激发导致了传统方法合成的 MOF 材料的典型绿色。
