Metal organic framework synthesis in the presence of surfactants: towards hierarchical MOFs?Electronic supplementary information (ESI) available. See DOI: 10.1039/c4ce02324b

• Main Authors: Seoane, B, Dikhtiarenko, A, Mayoral, A, Tellez, C, Coronas, J, Kapteijn, F, Gascon, J
• Format: Article
• Language: English
• ISSN: 1466-8033
• DOI: 10.1039/c4ce02324b

The effect of synthesis pH and H 2 O/EtOH molar ratio on the textural properties of different aluminium trimesate metal organic frameworks (MOFs) prepared in the presence of the well-known cationic surfactant cetyltrimethylammonium bromide (CTAB) at 120 °C was studied with the purpose of obtaining a MOF with hierarchical pore structure. Depending on the pH and the solvent used, different topologies were obtained (namely, MIL-96, MIL-100 and MIL-110). On the one hand, MIL-110 was obtained at lower temperatures than those commonly reported in the literature and without additives to control the pH; on the other hand, MIL-100 with crystallite sizes as small as 30 ± 10 nm could be easily synthesized in a mixture of H 2 O and EtOH with a H 2 O/EtOH molar ratio of 3.4 at pH 2.6 in the presence of CTAB. The resulting material displays a hierarchical porosity that combines the microporosity from the MOF and the non-ordered mesopores defined in between the MOF nanoparticles. Interestingly, the maximum of the pore size distribution could be varied between 3 and 33 nm. Finally, at pH 2.5 and using water as a solvent, platelets of MIL-96, a morphology never observed before for this MOF, were synthesized with a (001) preferential crystal orientation, the (001) plane running parallel to the bipyramidal cages of the MIL-96 topology. We report the effect of synthesis parameters on the textural properties of Al based MOFs synthesized in the presence CTAB.