Two strategies for encapsulating caffeine in ZIF-8 were carried out in this work: (1) one-step, in situ encapsulation where caffeine is added to a ZIF-8 synthesis solution and the MOF structure is formed around the entrapped molecule; and (2) ex situ encapsulation whereby caffeine is put into contact with previously synthesized or purchased ZIF-8. The products obtained were analyzed with XRD, TGA, Vis-UV, GC-MS, FTIR, (13)C NMR, and N 1s XPS to compare both encapsulation methods. Chemical and structural evidence indicated that the preferential adsorption site of caffeine molecules inside the ZIF-8 structure is near the methyl and CH groups of 2-methylimidazole ligand. These two groups interact with caffeine by van der Waals forces with methyl groups and via CH···O hydrogen bonds with C═O groups, respectively. In addition, the one-step encapsulation of caffeine in ZIF-8 produced high guest loading (ca. 28 wt % in only 2 h at 25 °C) and controlled release (during 27 days).

A simple and efficient one-step encapsulation of caffeine was carried out in MOF NH2-MIL-88B(Fe) and compared to the traditional three-stage synthesis–activation–encapsulation procedure.

JDF-L1 is a microporous titanosilicate exhibiting a layer structure with pore sizes of about 3 Å. It is consequently an attractive material to separate H 2-containing mixtures. This is the reason why JDF-L1, after disaggregation by means of hexadecyltrimethylammonium surfactant, has been combined with a carboxyl group containing copolyimide (6FDA-4MPD/6FDA-DABA 4:1) to produce mixed matrix membranes, which were applied to the separation of H 2 /CH 4 and O 2 /N 2 mixtures. Additionally, due to the sheet growth habit of JDF-L1 crystals, a preferential horizontal orientation of the JDF-L1 filler particles dispersed into the polymer was expected. This preferential orientation, which was achieved when the polymer solution concentration used during the membrane casting process was relatively low, has been studied by optical and electronic microscopy, X-ray diffraction and polarized Raman spectroscopy.