Amorphous (non-glassy) properties of Ti-based metal-organic frameworks A. Kono,1 and T. D. Bennett 2 1 University of Cambridge, UK and ENEOS Corporation, Japan, takeshita.ayano@eneos.com, 2 University of Cambridge, UK, tdb35@cam.ac.uk Research on metal-organic frameworks (MOFs), porous materials composed of inorganic nodes connected by organic linkers, have revealed their potentials in applications such as gas storage, gas separation and catalysis. Structural heterogeneity can be effective to enhance chemical and physical properties of MOFs. 1,2 Among MOFs with structural heterogeneity including defective, disordered, and amorphous systems, MOF glasses have attracted much attention in terms of processability. MOF glasses are amorphous solids with glass transition behaviour, which are induced mainly by the structural collapse of crystalline MOFs via melt-quenching, heating, high-pressure or mechanochemical methods. Ti-based MOFs reported by Zhao et al . are among the few examples of direct synthesis, and it is also reported to have a surface area greater than expected for an amorphous MOFs. 3 The glassy nature of MOFs not only improves the processability of MOF glasses themselves but also enables the synthesis of MOF crystal-glass-composites, 4 thereby broadening the strategies of material synthesis. For this aim, we investigated the thermal behaviour of Ti-based MOFs composed of titanium node and bisphenol A (Ti-BPA). In order to analyze the glass transition behaviour, we conducted the fast scanning calorimetry, which has been used to observe the glass transition temperature of polymers with intrinsic microporosity (PIMs) with a small number of conformational degrees of freedom. 5 Through its fast heating rates, this method allows the sample to be heated up to high temperatures for a short time and thus it is expected to avoid thermal decomposition, which might affect the observation of glass transition behavior. An irreversible endothermic feature was observed and Ti-BPA was shown to be an amorphous solid, showing no glass transition behaviour. References 1. T. D. Bennett, A. K. Cheetham, A. H. Fuchs and F. X. Coudert, Nat. Chem., 2016, 9 , 11. 2. A. F. Sapnik et al. , J. Mater. Chem. A, 2021, 9 , 27019. 3. Z. Yingbo, S. Y. Lee, N. Becknell, O. M. Yaghi, and C. A. Angell, J. Am. Chem. Soc. , 2016, 138, 10818. 4. S. Li et al. , Chem. Sci. , 2020, 11 , 9910. 5. H. Yin et al. , J. Phys. Chem. Lett. , 2018, 9 , 2003.
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