Investigating the chemical sensitivity of melting in zeolitic imidazolate frameworks

The number of zeolitic imidazolate frameworks (ZIFs) that form melt-quenched glasses remains limited, with most displaying the cag network topology. Here, we expand our studies to zni topology ZIFs, starting with ZIF-zni [Zn(Im)(2)] before changing its linker chemistry, by incorporating 2-methylimidazolate and 5-aminobenzimidazolate. ZIF-zni was found to melt and form a glass, with T-m = 576 degrees C and T-g = 322 degrees C, although it was not possible to prepare the glass without zinc oxide impurities. The addition of 2-methylimidazolate to the structure gave ZIF-61 [Zn(Im)(1.35)(mIm)(0.65)], which decomposed without passing through the liquid state. However, incorporating small quantities of 5-aminobenzimidazolate resulted in a ZIF [Zn(Im)(1.995)(abIm)(0.005)] with a lower melting temperature (T-m = 569 degrees C) than pure ZIF-zni, and no evidence of zinc oxide growth. This demonstrates the sensitivity of melting behaviour in ZIFs towards linker chemistry, with only a 0.25% variation capable of eliciting a 7 degrees C change in melting temperature. This study highlights the chemical sensitivity of melting in ZIFs and serves as a promising strategy for tuning their melting behaviour.

Automated summary

This study demonstrates the sensitivity of melting behavior in zeolitic imidazolate frameworks (ZIFs) towards linker chemistry, with small variations capable of eliciting significant changes in melting temperature. It provides a promising strategy for tuning the melting behavior of ZIFs.