The glass transition in the high-density amorphous Zn/Co-ZIF-4

Chem Commun (Camb). 2023 Sep 19. doi: 10.1039/d3cc02492j. Online ahead of print.ABSTRACTThe high-density amorphous phases (HDAs) of bimetallic zeolitic imidazolate frameworks (Zn/Co-ZIF-4) were prepared. The temperature dependence of the isobaric heat capacity (Cp) of ZIF-4 HDAs was measured to determine the glass transition temperature (Tg) of HDAs. The Tg non-linearly decreases with the molar ratio R, where R is Co/(Co + Zn), indicating the presence of a mixed-metal node effect. This effect arises from the non-linear increase of the degree of configurational freedom in the HDA as R increases. The degree of configurational freedom is inversely correlated with the network connectivity, which is, in turn, affected by variations in the MN4 (M: Zn or Co; N: nitrogen) tetrahedral symmetry in the ZIF-4 HDA. Overall, this work offers valuable insights into the glass transition of metal-organic frameworks.PMID:37723944 | DOI:10.1039/d3cc02492j

Source: Chemical Communications - September 19, 2023 Category: Chemistry Authors: Zijuan Du Ang Qiao Hemin Zhou Zhencai Li Wessel M W Winters Jiexin Zhu Guanjie He Ivan P Parkin Haizheng Tao Yuanzheng Yue Source Type: research