TY  - JOUR
A1  - Mondal, Suvendu Sekhar
A1  - Kreuzer, Alex
A1  - Behrens, Karsten
A1  - Schütz, Gisela
A1  - Holdt, Hans-Jürgen
A1  - Hirscher, Michael
T1  - Systematic experimental study on quantum sieving of hydrogen isotopes in metal-amide-imidazolate frameworks with narrow 1-D channels
JF  - ChemPhysChem : a European journal of chemical physics and physical chemistry
N2  - Quantum sieving of hydrogen isotopes is experimentally studied in isostructural hexagonal metal-organic frameworks having 1-D channels, named IFP-1, -3, -4 and -7. Inside the channels, different molecules or atoms restrict the channel diameter periodically with apertures larger (4.2 angstrom for IFP-1, 3.1 angstrom for IFP-3) and smaller (2.1 angstrom for IFP-7, 1.7 angstrom for IFP-4) than the kinetic diameter of hydrogen isotopes. From a geometrical point of view, no gas should penetrate into IFP-7 and IFP-4, but due to the thermally induced flexibility, so-called gate-opening effect of the apertures, penetration becomes possible with increasing temperature. Thermal desorption spectroscopy (TDS) measurements with pure H-2 or D-2 have been applied to study isotope adsorption. Further TDS experiments after exposure to an equimolar H-2/D-2 mixture allow to determine directly the selectivity of isotope separation by quantum sieving. IFP-7 shows a very low selectivity not higher than S=2. The selectivity of the materials with the smallest pore aperture IFP-4 has a constant value of S approximate to 2 for different exposure times and pressures, which can be explained by the 1-D channel structure. Due to the relatively small cavities between the apertures of IFP-4 and IFP-7, molecules in the channels cannot pass each other, which leads to a single-file filling. Therefore, no time dependence is observed, since the quantum sieving effect occurs only at the outermost pore aperture, resulting in a low separation selectivity.
KW  - gas adsorption
KW  - hydrogen isotopes
KW  - isotope separation
KW  - metal-organic frameworks
KW  - quantum sieving
Y1  - 2019
U6  - https://doi.org/10.1002/cphc.201900183
SN  - 1439-4235
SN  - 1439-7641
VL  - 20
IS  - 10
SP  - 1311
EP  - 1315
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Mondal, Suvendu Sekhar
A1  - Bhunia, Asamanjoy
A1  - Attallah, Ahmed G.
A1  - Matthes, Philipp R.
A1  - Kelling, Alexandra
A1  - Schilde, Uwe
A1  - Müller-Buschbaum, Klaus
A1  - Krause-Rehberg, Reinhard
A1  - Janiak, Christoph
A1  - Holdt, Hans-Jürgen
T1  - Study of the Discrepancies between Crystallographic Porosity and Guest Access into Cadmium-Imidazolate Frameworks and Tunable Luminescence Properties by Incorporation of Lanthanides
JF  - Chemistry - a European journal
N2  - An extended member of the isoreticular family of metal-imidazolate framework structures, IFP-6 (IFP=imidazolate framework Potsdam), based on cadmium metal and an in situ functionalized 2-methylimidazolate-4-amide-5-imidate linker is reported. A porous 3D framework with 1D hexagonal channels with accessible pore windows of 0.52nm has been synthesized by using an ionic liquid (IL) linker precursor. IFP-6 shows significant gas uptake capacity only for CO2 and CH4 at elevated pressure, whereas it does not adsorb N-2, H-2, and CH4 under atmospheric conditions. IFP-6 is assumed to deteriorate at the outside of the material during the activation process. This closing of the metal-organic framework (MOF) pores is proven by positron annihilation lifetime spectroscopy (PALS), which revealed inherent crystal defects. PALS results support the conservation of the inner pores of IFP-6. IFP-6 has also been successfully loaded with luminescent trivalent lanthanide ions (Ln(III)=Tb, Eu, and Sm) in a bottom-up one-pot reaction through the in situ generation of the linker ligand and in situ incorporation of photoluminescent Ln ions into the constituting network. The results of photoluminescence investigations and powder XRD provide evidence that the Ln ions are not doped as connectivity centers into the frameworks, but are instead located within the pores of the MOFs. Under UV light irradiation, Tb@IFP-6 and Eu@IFP-6 ((exc)=365nm) exhibit observable emission changes to a greenish and reddish color, respectively, as a result of strong Ln 4f emissions.
KW  - adsorption
KW  - cadmium
KW  - ionic liquids
KW  - luminescence
KW  - metal-organic frameworks
Y1  - 2016
U6  - https://doi.org/10.1002/chem.201504757
SN  - 0947-6539
SN  - 1521-3765
VL  - 22
SP  - 6905
EP  - 6913
PB  - Wiley-VCH
CY  - Weinheim
ER  -