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Fine tuning of pore architecture and morphology of stiffened Zeolitic Imidazolate Frameworks synthesized using fast current driven method and mixed ligand strategy
Microporous and Mesoporous Materials ( IF 4.8 ) Pub Date : 2021-09-08 , DOI: 10.1016/j.micromeso.2021.111409
P. Utpalla 1, 2 , S.K. Sharma 1, 2 , J. Mor 1 , J. Prakash 3 , J. Bahadur 2, 4 , P.K. Pujari 1, 2
Affiliation  

Zeolitic Imidazolate Frameworks (ZIFs) show great promise in molecular separation as well as recognition owing to their crystalline morphology consisting of a well designed pore architecture. However, the sieving performance of ZIFs remains limited due to their fixed pore sizes and framework flexibility. In the present study, fast current driven synthesis (FCDS) has been used to prepare the stiffened phase of mixed ligands (2-methylimidazole and benzimidazole) based ZIFs having tunable pore sizes and morphologies. X-ray diffraction has been used to determine the crystal structure of the frameworks, which were observed to be crystalline through a wide range of ligand ratio (benzimidazole fraction: ∼0.206–0.972). The random distribution of both the ligands in the frameworks has been established through complementary methods viz. Raman spectroscopy, Fourier transform infrared and scanning electron microscopy. Morphology of the frameworks was observed to vary from micrometer size individual crystals to spherical aggregates of inter-grown nanocrystals to individual nanocrystals. Pore sizes determined using positronium lifetime measurements were observed to be consistent with the literature for pure phase of ZIF-7 and stiffened ZIF-8. The pore sizes were observed to vary with the benzimidazole ligand fraction confirming that mixed ligand strategy can be used to efficiently tune the pore sizes of the frameworks. Positronium diffusion investigation confirms that pore interconnectivity is inferior as compared to stiffened ZIF-8 but superior than ZIF-7 in these mixed ligand frameworks.



中文翻译:

使用快速电流驱动方法和混合配体策略合成的硬化沸石咪唑酯骨架的孔结构和形态的微调

沸石咪唑酯骨架 (ZIF) 由于其结晶形态由精心设计的孔结构组成,因此在分子分离和识别方面显示出巨大的前景。然而,由于 ZIF 的孔径固定和框架灵活性,其筛分性能仍然有限。在本研究中,快速电流驱动合成 (FCDS) 已被用于制备具有可调孔径和形态的基于混合配体(2-甲基咪唑和苯并咪唑)的 ZIF 的硬化相。X 射线衍射已被用于确定骨架的晶体结构,通过广泛的配体比例(苯并咪唑分数:~0.206-0.972)观察到它们是结晶的。框架中两种配体的随机分布是通过互补方法建立的,即。拉曼光谱,傅里叶变换红外和扫描电子显微镜。观察到框架的形态从微米尺寸的单个晶体到相互生长的纳米晶体的球形聚集体到单个纳米晶体不等。观察到使用正电子寿命测量确定的孔径与 ZIF-7 和硬化 ZIF-8 纯相的文献一致。观察到孔径随苯并咪唑配体分数而变化,证实混合配体策略可用于有效调整框架的孔径。正电子扩散研究证实,在这些混合配体框架中,孔互连性不如硬化的 ZIF-8,但优于 ZIF-7。观察到框架的形态从微米尺寸的单个晶体到相互生长的纳米晶体的球形聚集体到单个纳米晶体不等。观察到使用正电子寿命测量确定的孔径与 ZIF-7 和硬化 ZIF-8 纯相的文献一致。观察到孔径随苯并咪唑配体分数而变化,证实混合配体策略可用于有效调整框架的孔径。正电子扩散研究证实,在这些混合配体框架中,孔互连性不如硬化的 ZIF-8,但优于 ZIF-7。观察到框架的形态从微米尺寸的单个晶体到相互生长的纳米晶体的球形聚集体到单个纳米晶体不等。观察到使用正电子寿命测量确定的孔径与 ZIF-7 和硬化 ZIF-8 纯相的文献一致。观察到孔径随苯并咪唑配体分数而变化,证实混合配体策略可用于有效调整框架的孔径。正电子扩散研究证实,在这些混合配体框架中,孔互连性与硬化的 ZIF-8 相比较差,但优于 ZIF-7。观察到使用正电子寿命测量确定的孔径与 ZIF-7 和硬化 ZIF-8 纯相的文献一致。观察到孔径随苯并咪唑配体分数而变化,证实混合配体策略可用于有效调整框架的孔径。正电子扩散研究证实,在这些混合配体框架中,孔互连性不如硬化的 ZIF-8,但优于 ZIF-7。观察到使用正电子寿命测量确定的孔径与 ZIF-7 和硬化 ZIF-8 纯相的文献一致。观察到孔径随苯并咪唑配体分数而变化,证实混合配体策略可用于有效调整框架的孔径。正电子扩散研究证实,在这些混合配体框架中,孔互连性不如硬化的 ZIF-8,但优于 ZIF-7。

更新日期:2021-09-13
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