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  - Balischewski, Christian
A1  - Bhattacharyya, Biswajit
A1  - Sperlich, Eric
A1  - Günter, Christina
A1  - Beqiraj, Alkit
A1  - Klamroth, Tillmann
A1  - Behrens, Karsten
A1  - Mies, Stefan
A1  - Kelling, Alexandra
A1  - Lubahn, Susanne
A1  - Holtzheimer, Lea
A1  - Nitschke, Anne
A1  - Taubert, Andreas
T1  - Tetrahalidometallate(II) ionic liquids with more than one metal
BT  - the effect of bromide versus chloride
JF  - Chemistry - a European journal
N2  - Fifteen N-butylpyridinium salts - five monometallic [C4Py](2)[MBr4] and ten bimetallic [C4Py](2)[(M0.5M0.5Br4)-M-a-Br-b] (M=Co, Cu, Mn, Ni, Zn) - were synthesized, and their structures and thermal and electrochemical properties were studied. All the compounds are ionic liquids (ILs) with melting points between 64 and 101 degrees C. Powder and single-crystal X-ray diffraction show that all ILs are isostructural. The electrochemical stability windows of the ILs are between 2 and 3 V. The conductivities at room temperature are between 10(-5) and 10(-6) S cm(-1). At elevated temperatures, the conductivities reach up to 10(-4) S cm(-1) at 70 degrees C. The structures and properties of the current bromide-based ILs were also compared with those of previous examples using chloride ligands, which illustrated differences and similarities between the two groups of ILs.
KW  - electrochemistry
KW  - ionic liquids
KW  - metal-containing ionic liquids;
KW  - N-butylpyridinium bromide
KW  - tetrahalidometallates
Y1  - 2022
U6  - https://doi.org/10.1002/chem.202201068
SN  - 1521-3765
VL  - 28
IS  - 64
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Mondal, Suvendu Sekhar
A1  - Behrens, Karsten
A1  - Kelling, Alexandra
A1  - Nabein, Hans-Peter
A1  - Schilde, Uwe
A1  - Holdt, Hans-Jürgen
T1  - Two Cd-II/Co-II-Imidazolate Coordination Polymers: Syntheses, Crystal Structures, Stabilities, and Luminescent/Magnetic Properties
JF  - Zeitschrift für anorganische und allgemeine Chemie
N2  - Cadmium(II) based 2D coordination polymer [Cd(L1)(2)(DMF)(2)] (1) (L1 = 4,5-dicyano-2-methylimidazolate, DMF = N,N'-dimethylformamide) and 2D cobalt(II)-imidazolate framework [Co(L3)(4)] (2) (L3 = 4,5-diamide-2-ethoxyimidazolate) were synthesized under solvothermal reaction conditions. The materials were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X-ray diffraction measurement (PXRD) and single-crystal X-ray diffraction. Compound 1 has hexacoordinate Cd-II ions and forms a zigzag chain-like coordination polymer structure, whereas compound 2 exhibits a 2D square grid type structure. The thermal stability analysis reveals that 2 showed an exceptional thermal stability up to 360 degrees C. Also, 2 maintained its fully crystalline integrity in boiling water as confirmed by PXRD. The solid state luminescent property of 1 was not observed at room temperature. Compound 2 showed an independent high spin central Co-II atom.
KW  - Cobalt
KW  - Cadmium
KW  - Coordination polymers
KW  - Crystal structures
KW  - Imidazole
Y1  - 2015
U6  - https://doi.org/10.1002/zaac.201500526
SN  - 0044-2313
SN  - 1521-3749
VL  - 641
IS  - 11
SP  - 1991
EP  - 1997
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - GEN
A1  - Taubert, Andreas
A1  - Balischewski, Christian
A1  - Hentrich, Doreen
A1  - Elschner, Thomas
A1  - Eidner, Sascha
A1  - Günter, Christina
A1  - Behrens, Karsten
A1  - Heinze, Thomas
T1  - Water-soluble cellulose derivatives are sustainable additives for biomimetic calcium phosphate mineralization
N2  - The effect of cellulose-based polyelectrolytes on biomimetic calcium phosphate mineralization is described. Three cellulose derivatives, a polyanion, a polycation, and a polyzwitterion were used as additives. Scanning electron microscopy, X-ray diffraction, IR and Raman spectroscopy show that, depending on the composition of the starting solution, hydroxyapatite or brushite precipitates form. Infrared and Raman spectroscopy also show that significant amounts of nitrate ions are incorporated in the precipitates. Energy dispersive X-ray spectroscopy shows that the Ca/P ratio varies throughout the samples and resembles that of other bioinspired calcium phosphate hybrid materials. Elemental analysis shows that the carbon (i.e., polymer) contents reach 10% in some samples, clearly illustrating the formation of a true hybrid material. Overall, the data indicate that a higher polymer concentration in the reaction mixture favors the formation of polymer-enriched materials, while lower polymer concentrations or high precursor concentrations favor the formation of products that are closely related to the control samples precipitated in the absence of polymer. The results thus highlight the potential of (water-soluble) cellulose derivatives for the synthesis and design of bioinspired and bio-based hybrid materials.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 354 
KW  - cellulose
KW  - polyamine
KW  - polyammonium salt
KW  - polycarboxylate
KW  - polyzwitterion
KW  - calcium phosphate
KW  - biomineralization
KW  - brushite
KW  - hydroyxapatite
KW  - biomaterial
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-400453
ER  - 
TY  - JOUR
A1  - Taubert, Andreas
A1  - Balischewski, Christian
A1  - Hentrich, Doreen
A1  - Elschner, Thomas
A1  - Eidner, Sascha
A1  - Günter, Christina
A1  - Behrens, Karsten
A1  - Heinze, Thomas
T1  - Water-Soluble Cellulose Derivatives Are Sustainable Additives for Biomimetic Calcium Phosphate Mineralization
JF  - Inorganics : open access journal
N2  - The effect of cellulose-based polyelectrolytes on biomimetic calcium phosphate mineralization is described. Three cellulose derivatives, a polyanion, a polycation, and a polyzwitterion were used as additives. Scanning electron microscopy, X-ray diffraction, IR and Raman spectroscopy show that, depending on the composition of the starting solution, hydroxyapatite or brushite precipitates form. Infrared and Raman spectroscopy also show that significant amounts of nitrate ions are incorporated in the precipitates. Energy dispersive X-ray spectroscopy shows that the Ca/P ratio varies throughout the samples and resembles that of other bioinspired calcium phosphate hybrid materials. Elemental analysis shows that the carbon (i.e., polymer) contents reach 10% in some samples, clearly illustrating the formation of a true hybrid material. Overall, the data indicate that a higher polymer concentration in the reaction mixture favors the formation of polymer-enriched materials, while lower polymer concentrations or high precursor concentrations favor the formation of products that are closely related to the control samples precipitated in the absence of polymer. The results thus highlight the potential of (water-soluble) cellulose derivatives for the synthesis and design of bioinspired and bio-based hybrid materials.
KW  - cellulose
KW  - polyamine
KW  - polyammonium salt
KW  - polycarboxylate
KW  - polyzwitterion
KW  - calcium phosphate
KW  - biomineralization
KW  - brushite
KW  - hydroyxapatite
KW  - biomaterial
Y1  - 2016
U6  - https://doi.org/10.3390/inorganics4040033
SN  - 2304-6740
VL  - 4
PB  - MDPI
CY  - Basel
ER  - 
TY  - GEN
A1  - Mondal, Suvendu Sekhar
A1  - Behrens, Karsten
A1  - Matthes, Philipp R.
A1  - Schönfeld, Fabian
A1  - Nitsch, Jörn
A1  - Steffen, Andreas
A1  - Primus, Philipp-Alexander
A1  - Kumke, Michael Uwe
A1  - Müller-Buschbaum, Klaus
A1  - Holdt, Hans-Jürgen
T1  - White light emission of IFP-1 by in situ co-doping of the MOF pore system with Eu3+ and Tb3+
N2  - Co-doping of the MOF 3∞[Zn(2-methylimidazolate-4-amide-5-imidate)] (IFP-1 = Imidazolate Framework Potsdam-1) with luminescent Eu3+ and Tb3+ ions presents an approach to utilize the porosity of the MOF for the intercalation of luminescence centers and for tuning of the chromaticity to the emission of white light of the quality of a three color emitter. Organic based fluorescence processes of the MOF backbone as well as metal based luminescence of the dopants are combined to one homogenous single source emitter while retaining the MOF's porosity. The lanthanide ions Eu3+ and Tb3+ were doped in situ into IFP-1 upon formation of the MOF by intercalation into the micropores of the growing framework without a structure directing effect. Furthermore, the color point is temperature sensitive, so that a cold white light with a higher blue content is observed at 77 K and a warmer white light at room temperature (RT) due to the reduction of the organic emission at higher temperatures. The study further illustrates the dependence of the amount of luminescent ions on porosity and sorption properties of the MOF and proves the intercalation of luminescence centers into the pore system by low-temperature site selective photoluminescence spectroscopy, SEM and EDX. It also covers an investigation of the border of homogenous uptake within the MOF pores and the formation of secondary phases of lanthanide formates on the surface of the MOF. Crossing the border from a homogenous co-doping to a two-phase composite system can be beneficially used to adjust the character and warmth of the white light. This study also describes two-color emitters of the formula Ln@IFP-1a–d (Ln: Eu, Tb) by doping with just one lanthanide Eu3+ or Tb3+.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 190 
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-79953
SP  - 4623
EP  - 4631
ER  - 
TY  - JOUR
A1  - Mondal, Suvendu Sekhar
A1  - Behrens, Karsten
A1  - Matthes, Philipp R.
A1  - Schönfeld, Fabian
A1  - Nitsch, Jörn
A1  - Steffen, Andreas
A1  - Primus, Philipp-Alexander
A1  - Kumke, Michael Uwe
A1  - Müller-Buschbaum, Klaus
A1  - Holdt, Hans-Jürgen
T1  - White light emission of IFP-1 by in situ co-doping of the MOF pore system with Eu3+ and Tb3+
JF  - Journal of materials chemistry : C, Materials for optical and electronic devices
N2  - Co-doping of the MOF 3∞[Zn(2-methylimidazolate-4-amide-5-imidate)] (IFP-1 = Imidazolate Framework Potsdam-1) with luminescent Eu3+ and Tb3+ ions presents an approach to utilize the porosity of the MOF for the intercalation of luminescence centers and for tuning of the chromaticity to the emission of white light of the quality of a three color emitter. Organic based fluorescence processes of the MOF backbone as well as metal based luminescence of the dopants are combined to one homogenous single source emitter while retaining the MOF's porosity. The lanthanide ions Eu3+ and Tb3+ were doped in situ into IFP-1 upon formation of the MOF by intercalation into the micropores of the growing framework without a structure directing effect. Furthermore, the color point is temperature sensitive, so that a cold white light with a higher blue content is observed at 77 K and a warmer white light at room temperature (RT) due to the reduction of the organic emission at higher temperatures. The study further illustrates the dependence of the amount of luminescent ions on porosity and sorption properties of the MOF and proves the intercalation of luminescence centers into the pore system by low-temperature site selective photoluminescence spectroscopy, SEM and EDX. It also covers an investigation of the border of homogenous uptake within the MOF pores and the formation of secondary phases of lanthanide formates on the surface of the MOF. Crossing the border from a homogenous co-doping to a two-phase composite system can be beneficially used to adjust the character and warmth of the white light. This study also describes two-color emitters of the formula Ln@IFP-1a–d (Ln: Eu, Tb) by doping with just one lanthanide Eu3+ or Tb3+.
Y1  - 2015
U6  - https://doi.org/10.1039/C4TC02919D
SN  - 2050-7534
SN  - 2050-7526
VL  - 18
IS  - 3
SP  - 4623
EP  - 4631
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Mondal, Suvendu Sekhar
A1  - Behrens, Karsten
A1  - Matthes, Philipp R.
A1  - Schönfeld, Fabian
A1  - Nitsch, Jörn
A1  - Steffen, Andreas
A1  - Primus, Philipp-Alexander
A1  - Kumke, Michael Uwe
A1  - Müller-Buschbaum, Klaus
A1  - Holdt, Hans-Jürgen
T1  - White light emission of IFP-1 by in situ co-doping of the MOF pore system with Eu3+ and Tb3+
JF  - Journal of materials chemistry : C, Materials for optical and electronic devices
Y1  - 2015
U6  - https://doi.org/10.1039/c4tc02919d
SN  - 2050-7526
SN  - 2050-7534
VL  - 3
IS  - 18
SP  - 4623
EP  - 4631
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -