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7730560 
Journal Article 
Sorption and breathing properties of difluorinated MIL-47 and Al-MIL-53 frameworks 
Biswas, S; Couck, S; Denysenko, D; Bhunia, A; Grzywa, M; Denayer, JFM; Volkmer, D; Janiak, C; Van Der Voort, P 
2013 
1 
Microporous and Mesoporous Materials
ISSN: 1387-1811 
ELSEVIER SCIENCE BV 
AMSTERDAM 
181 
175-181 
English 
WOS:000325676500025 
Synthesis of two difluorinated metal hydroxo terephthalates [M III(OH)(BDC-F2)]·n(guests) (MIII = V, MIL-47-F2-AS or 1-AS; Al, Al-MIL-53-F2-AS or2-AS) (BDC-F2 = 2,5-difluoro-1,4-benzenedicarboxylate; AS = as-synthesized) has been accomplished by a hydrothermal method using microwave irradiation (1-AS) or electric heating (2-AS), respectively. The empty-pore forms of the title compounds [VIV(O)(BDC-F2] (MIL-47-F2, 1) and [AlIII(OH)(BDC-F2)] (Al-MIL-53-F2, 2) have been prepared after removal of the unreacted or guest H2BDC-F 2 molecules under vacuum by direct thermal treatment or solvent-exchange of occluded molecules followed by thermal activation. The high thermal stability of the compounds (340 C, 1; 480 C, 2) has been revealed by thermogravimetric analysis. N2, CO2 and n-hexane sorption analyses confirm that the thermally activated compounds possess noticeable microporosity. An ideal CO2/N2 selectivity value of 11 has been deduced for 2 from the single component adsorption isotherms. The breathing behavior of 2 upon adsorption of CO2 and n-hexane are similar to monofluorinated Al-MIL-53, but different from parent Al-MIL-53. H2O sorption analyses demonstrate that the fluorination induce a certain extent of hydrophobicity in the frameworks, similar to their monofluorinated counterparts. Remarkably, the n-hexane adsorption capacity of both mono- and difluorinated MIL-47 at 50 C and p/p0 = 0.5 exceeds that of parent MIL-47 owing to the enhanced hydrophobicity achieved through fluorination of their frameworks. © 2013 Elsevier Inc. All rights reserved. 
V and Al-based MOFs; Terephthalate linker; Fluorination; Gas/vapor adsorption; Breathing behavior