An international research team has developed a new synthetic technique for the fabrication of large-sized inorganic-organic hybrid glasses, and using X-ray pair distribution function (PDF) analysis at Diamond, the team revealed important local structure differences. The work has now been published in Angewandte Chemie International Edition, and is particularly important for the discovery and scale-up of new metal coordination compound glasses.
Crystalline metal coordination compounds are a class of hybrid materials composed of metal ions coordinated to organic linkers, forming frameworks with various dimensionalities and functionalities. Several of metal coordination compounds can be vitrified to bulk samples. However, the vitrification of these materials is usually realized by the conventional melt-quenching technique, which typically needs special conditions (e.g., high temperatures and/or pressure, inert gas, or vacuum) to finally obtain small-sized glass samples.
A research team from Zhejiang University, in collaboration with other scientists from Europe and USA, has developed a new synthetic technique, so-called “Crystallization-Suppressing Approach”, by which the large-sized inorganic-organic hybrid glasses were fabricated at low temperature (i.e., 373 K) and under ambient conditions. In this technique, the crystallization of two-dimensional (2D) zeolitic-imidazolate framework-7-III (ZIF-7-III) was suppressed by alcohol/acid solution, forming a supramolecular metal inorganic-organic complex (MIOC) glass with large-size (Figure 1) and unique properties.
By performing the X-ray pair distribution function (PDF) analysis using Diamond's I51-1 beamline and ultrahigh field 67Zn nuclear magnetic resonance measurements, the international team revealed the local structure difference between the as-synthesized ZIF-7-III crystal and MIOC glass. The entire work has now been published in Angewandte Chemie International Edition. The work is particularly important for the discovery and scale-up of new metal coordination compound glasses.
Prof. Jianrong Qiu is the director of Micro & Nano Photonics institute at Zhejiang University and a senior author of the paper. He said:
To understand the mechanisms of glass formation after crystallization-suppressing of ZIF, it is important to know the atom-atom correlations in the short and medium range order of the crystalline and glassy networks. The synchrotron diffraction and PDF measurements enable us to determine the local structure of our glassy samples.
Prof. Yuanzheng Yue of Aalborg University, a senior author of the paper, added:
A big challenge for up-scaling the MOF glass production is the difficulty in synthesizing large-sized MOF crystals and glasses. However, the new method exhibits a potential to fabricate large-size bulk MOF glasses. To improve the chemical stability and quality of such bulk glasses, it is crucial to understand their structure.
To reveal the local structure of the fabricated MIOC glass, the research team analyzed the X-ray PDF results obtained from Diamond Beamline I15-1. By doing so, they were able to accurately determine how the chemical bonding of MIOC glass responded to the interaction of ZIF crystals with ethanol/HNO3 solutions. Furthermore, they unraveled the atom-atom correlations in both ZIF-7-III crystals and MIOC glasses using PDF data (Figure 2), that cannot be observed by other structural characterization techniques. The PDF data confirms that the as-synthesized MIOC glass possesses molecular nature, where the observed Zn-Zn correlation in the PDF data of ZIF-7-III crystal was interrupted by nitrates, and hence, the medium-range order correlations (i.e., r >6 Å) were not observed in the PDF data of the glass sample. This verified the conversion of a 2D ZIF-7-III network into a 3D hydrogen-bonded molecular network. The X-ray PDF measurements are an important technique to evaluate the atomic bond distances in matter and examine whether the local structure has been changed after certain chemical modifications. The PDF results also improve their understanding for the amorphization mechanisms of metal coordination compounds.
Dr. Mohamed Ali, a postdoctoral researcher in the Lab of Prof. Jianrong Qiu and the first author of the paper, commented:
Diamond Light Source has been a cornerstone of our research. Access to the beamlines allowed us to generate high quality PDF data which helped determine local structure of MIOC glass and understand how the glass is formed. This allowed us to answer structural questions regarding MIOC glass.
After researchers realized the structural aspects of their MIOC glass using X-ray PDF analysis and fabricated transparent and large-sized MIOC glass at 373 K and under ambient conditions, they explored the photonic functionalities of MIOC glass through incorporating luminescent organic dyes into the glass network (Figure 3). The dye-doped MIOC glasses showed sharp and efficient blue to red luminescence. In addition, they succeeded in fabricating dye-doped MIOC glasses in different shapes such as 3D bulk objects, sheets, and fibers. Owing to the low glass transition temperature of MIOC glass (i.e., < 300 K) as well as the presence of a small amount of ethanol in the glass network, the sample is dynamically flexible at room temperature. Thus the first MIOC fibers doped with dyes were fabricated, which can generate polarized light with a large polarization ratio up to 47 %. The observed polarization ratio from dye-doped MIOC fibers is larger than those of perovskite nanocrystal embedded polymer composite films, dye intercalated in ordered layered films, and oxide nanocrystal. These results suggest the potential of dye-doped metal coordination compound glasses as a polarized light source.
To find out more about the I15-1 beamline or discuss potential applications, please contact Principal Beamline Scientist Dr. Phil Chater: firstname.lastname@example.org
Ali M. A., Winters, W. M. W., Mohamed M. A., Tan, D., Zheng G., Madsen R. S. K., Magdysyuk O. V., Diaz-Lopez M., Cai B., Gong N., Xu Y., Hung I., Gan Z., Sen S., Sun H-T., Bennett T. D., Liu X., Yue Y., Qui J. Fabrication of Super-Sized Metal Inorganic-Organic Hybrid Glass with Supramolecular Network via Crystallization-Suppressing Approach, Angew. Chemie. Int. Ed. (2023), e202218094. DOI: 10.1002/anie.202218094.
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