Three porous Al-BTCs (BTC: benzenetricarboxylate) have been synthesized in wide reaction conditions including heating methods (conventional electric and microwave heating) and reaction time. It has been found that an Al-BTC called MIL-100 converts into another phase (MIL-110) with increasing time and eventually a different phase (MIL-96) is observed. This phase-conversion is the first observation of the possibility to synthesize three MOFs from the very same reactant mixtures, and may be explained with the relative stability of the Al-BTCs (MIL-96 > MIL-110 > MIL-100) since the stability of a porous material may increase with decreasing porosity or pore size of the phases. The inter-conversion of a less stable Al-BTC into a more stable one is carried out via recombination of the degraded precursors. Moreover, due to the advantage of rapid crystallization of microwave heating, it can be found that microwave synthesis selectively leads to highly porous materials like MIL-100 or MIL-110. This phase-selective synthesis with microwaves is similar to the synthesis of another MOFs (Cr-BDCs) and aluminophosphates, and may lead to a new way to synthesize highly porous (unstable) materials.
Bibliographical noteFunding Information:
This work was supported by a grant (B551179-10-03-00) from the cooperative R&D Program funded by the Korea Research Council Industrial Science and Technology, Republic of Korea. Authors would like to express sincere thanks for the very helpful comments of Dr. Jong-San Chang of KRICT. S.H.J. also acknowledges supporting and collaboration of Catalysis Center for Molecular Engineering of KRICT.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials