Weckhuysen Bert M, Öztürk Zafer, Brand Rogier P, Boereboom Jelle M, Meirer Florian
Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584, CG, Utrecht, The Netherlands.
Chemistry. 2019 Jun 18;25(34):8070-8084. doi: 10.1002/chem.201806414. Epub 2019 May 16.
Surface-mounted metal-organic frameworks (SURMOFs) are crystalline films of MOFs and have garnered a great deal of attention in the past years. So far, thin-film MOF research has been mainly focused on the synthesis and the exploration of potential applications of these materials, while a detailed understanding of their growth is still lacking. In this report evidence is provided for the inter-grown nature of surface-mounted thin films of Zn-ZIF-8 (SURZIF-8; ZIF=zeolitic imidazolate framework). Two distinct SURZIF-8 thin films have been made through layer-by-layer (LBL) growth after applying 20 and 50 LBL cycles. They have been characterized with atomic force microscopy (AFM) and Raman micro-spectroscopy. A detailed analysis of the Raman mapping data, inter alia using principal component analysis (PCA), revealed the existence of phase boundaries within the 20-cycle thin film, while the 50-cycle thin film is chemically more homogeneous. To further analyze these chemical heterogeneities, density functional theory (DFT) calculations were performed of three theoretical models providing spectroscopic fingerprints of the molecular vibrations associated with the Zn-ZIF-8 thin films. Based on these calculations and the experimental data distinct vibrational markers indicative for the presence of defects sites were identified.
表面安装金属有机框架（SURMOFs）是金属有机框架的晶体薄膜，在过去几年中受到了广泛关注。到目前为止，薄膜金属有机框架的研究主要集中在这些材料的合成和潜在应用的探索上，而对其生长的详细了解仍然不足。在本报告中，提供了关于Zn-ZIF-8表面安装薄膜（SURZIF-8；ZIF=沸石咪唑酯框架）共生性质的证据。在进行20次和50次逐层（LBL）生长循环后，通过逐层生长制备了两种不同的SURZIF-8薄膜。它们已通过原子力显微镜（AFM）和拉曼显微光谱进行了表征。对拉曼映射数据的详细分析，特别是使用主成分分析（PCA），揭示了20次循环薄膜中存在相界，而50次循环薄膜在化学上更均匀。为了进一步分析这些化学不均匀性，对三个理论模型进行了密度泛函理论（DFT）计算，这些模型提供了与Zn-ZIF-8薄膜相关的分子振动的光谱指纹。基于这些计算和实验数据，确定了指示缺陷位点存在的独特振动标记。
