TY  - JOUR
A1  - Kröner, Dominik
A1  - Krüger, Hartmut
A1  - Thesen, Manuel W.
T1  - Electronic structure calculations for Hole-Transporting Triphenylamine Derivatives in Polymer Light-Emitting Diodes
JF  - Macromolecular theory and simulations
N2  - Hole-transporting polymers based on polyethene-triphenylamine derivatives are investigated with respect to their UV/Vis spectra. Two substituents, N-phenyl-1-naphthylamine and carbazole, are examined as their respective polymer light-emitting diodes (PLEDs) show very different luminous efficiencies. In order to identify the origin of these phenomena electronic structure calculations based on TD-DFT were performed using monomer models of the hole-transporting polymers. In experiment these hole-transporting polymers show very specific differences in their absorption and emission (fluorescence and phosphorescence) spectra. The analysis of the simulated absorption and emission spectra, the MOs as well as the ground and excited state geometries give explanations for the different optical performances of the corresponding PLEDs.
KW  - charge transport
KW  - luminescence
KW  - organic light-emitting diodes
KW  - polystyrenes
KW  - quantum chemistry
Y1  - 2011
U6  - https://doi.org/10.1002/mats.201100016
SN  - 1022-1344
VL  - 20
IS  - 9
SP  - 790
EP  - 805
PB  - Wiley-Blackwell
CY  - Malden
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  - 
TY  - JOUR
A1  - Burek, Katja
A1  - Dengler, Joachim
A1  - Emmerling, Franziska
A1  - Feldmann, Ines
A1  - Kumke, Michael Uwe
A1  - Stroh, Julia
T1  - Lanthanide Luminescence Revealing the Phase Composition in Hydrating Cementitious Systems
JF  - ChemistryOpen
N2  - The hydration process of Portland cement in a cementitious system is crucial for development of the high‐quality cement‐based construction material. Complementary experiments of X‐ray diffraction analysis (XRD), scanning electron microscopy (SEM) and time‐resolved laser fluorescence spectroscopy (TRLFS) using europium (Eu(III)) as an optical probe are used to analyse the hydration process of two cement systems in the absence and presence of different organic admixtures. We show that different analysed admixtures and the used sulphate carriers in each cement system have a significant influence on the hydration process, namely on the time‐dependence in the formation of different hydrate phases of cement. Moreover, the effect of a particular admixture is related to the type of sulphate carrier used. The quantitative information on the amounts of the crystalline cement paste components is accessible via XRD analysis. Distinctly different morphologies of ettringite and calcium−silicate−hydrates (C−S−H) determined by SEM allow visual conclusions about formation of these phases at particular ageing times. The TRLFS data provides information about the admixture influence on the course of the silicate reaction. The dip in the dependence of the luminescence decay times on the hydration time indicates the change in the structure of C−S−H in the early hydration period. Complementary information from XRD, SEM and TRLFS provides detailed information on distinct periods of the cement hydration process.
KW  - cement admixtures
KW  - cement hydration
KW  - Europium
KW  - luminescence
KW  - SEM
KW  - X-ray diffraction
Y1  - 2019
U6  - https://doi.org/10.1002/open.201900249
SN  - 2191-1363
VL  - 8
IS  - 12
SP  - 1441
EP  - 1452
PB  - Wiley-VCH-Verl.
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Tao, Lumi
A1  - Liu, Yuchuan
A1  - Wu, Dan
A1  - Wei, Qiao-Hua
A1  - Taubert, Andreas
A1  - Xie, Zailai
T1  - Luminescent Ionogels with Excellent Transparency, High Mechanical Strength, and High Conductivity
JF  - Nanomaterials
N2  - The paper describes a new kind of ionogel with both good mechanical strength and high conductivity synthesized by confining the ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide ([Bmim][NTf₂]) within an organic–inorganic hybrid host. The organic–inorganic host network was synthesized by the reaction of methyltrimethoxysilane (MTMS), tetraethoxysilane (TEOS), and methyl methacrylate (MMA) in the presence of a coupling agent, offering the good mechanical strength and rapid shape recovery of the final products. The silane coupling agent 3-methacryloxypropyltrimethoxysilane (KH-570) plays an important role in improving the mechanical strength of the inorganic–organic hybrid, because it covalently connected the organic component MMA and the inorganic component SiO₂. Both the thermal stability and mechanical strength of the ionogel significantly increased by the addition of IL. The immobilization of [Bmim][NTf₂] within the ionogel provided the final ionogel with an ionic conductivity as high as ca. 0.04 S cm⁻¹ at 50 °C. Moreover, the hybrid ionogel can be modified with organosilica-modified carbon dots within the network to yield a transparent and flexible ionogel with strong excitation-dependent emission between 400 and 800 nm. The approach is, therefore, a blueprint for the construction of next-generation multifunctional ionogels.
KW  - ionic liquid
KW  - ionogel
KW  - carbon dots
KW  - organic–inorganic hybrid
KW  - luminescence
KW  - mechanical strength
Y1  - 2020
U6  - https://doi.org/10.3390/nano10122521
SN  - 2079-4991
VL  - 10
IS  - 12
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Dettmann, Sophie
A1  - Huittinen, Nina Maria
A1  - Nicolas, Jahn
A1  - Kretzschmar, Jerome
A1  - Kumke, Michael
A1  - Kutyma, Tamara
A1  - Lohmann, Janik
A1  - Reich, Tobias
A1  - Schmeide, Katja
A1  - Azzam, Salim Shams Aldin
A1  - Spittler, Leon
A1  - Stietz, Janina
T1  - Influence of gluconate on the retention of Eu(III), Am(III), Th(IV), Pu(IV), and U(VI) by C-S-H (C/S = 0.8)
JF  - Frontiers in Nuclear Engineering
N2  - The retention of actinides in different oxidation states (An(X), X = III, IV, VI) by a calcium-silicate-hydrate (C-S-H) phase with a Ca/Si (C/S) ratio of 0.8 was investigated in the presence of gluconate (GLU). The actinides considered were Am(III), Th(IV), Pu(IV), and U(VI). Eu(III) was investigated as chemical analogue for Am(III) and Cm(III). In addition to the ternary systems An(X)/GLU/C-S-H, also binary systems An(X)/C-S-H, GLU/C-S-H, and An(X)/GLU were studied. Complementary analytical techniques were applied to address the different specific aspects of the binary and ternary systems. Time-resolved laser-induced luminescence spectroscopy (TRLFS) was applied in combination with parallel factor analysis (PARAFAC) to identify retained species and to monitor species-selective sorption kinetics. ¹³C and ²⁹Si magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were applied to determine the bulk structure and the composition of the C-S-H surface, respectively, in the absence and presence of GLU. The interaction of Th(IV) with GLU in different electrolytes was studied by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS). The influence of GLU on An(X) retention was investigated for a large concentration range up to 10⁻² M. The results showed that GLU had little to no effect on the overall An(X) retention by C-S-H with C/S of 0.8, regardless of the oxidation state of the actinides. For Eu(III), the TRLFS investigations additionally implied the formation of a Eu(III)-bearing precipitate with dissolved constituents of the C-S-H phase, which becomes structurally altered by the presence of GLU. For U(VI) sorption on the C-S-H phase, only a small influence of GLU could be established in the luminescence spectroscopic investigations, and no precipitation of U(VI)-containing secondary phases could be identified.
KW  - actinide
KW  - organic ligand
KW  - sorption
KW  - cementitious material
KW  - concrete
KW  - luminescence
Y1  - 2023
U6  - https://doi.org/10.3389/fnuen.2023.1124856
SN  - 2813-3412
VL  - 2
PB  - Frontiers Media
CY  - Lausanne
ER  -