Showing papers by "Juergen Eckert published in 2015"

Understanding the H2 Sorption Trends in the M-MOF-74 Series (M = Mg, Ni, Co, Zn)

Abstract: Electronic structure calculations and simulations of H2 sorption were performed in four members of the M-MOF-74 series: Mg-MOF-74, Ni-MOF-74, Co-MOF-74, and Zn-MOF-74. Notable differences were observed in the partial charge and polarizability of the metal ions derived from the electronic structure calculations. The modeling parameters obtained from the electronic structure calculations were found to influence certain features in the experimentally observed H2 sorption trends in the M-MOF-74 series. The simulations were performed with the inclusion of explicit many-body polarization, which was required to reproduce the experimental H2 sorption observables (i.e., sorption isotherms and isosteric heats of adsorption (Qst)) and the H2–metal interaction in all four MOFs using classical molecular simulation. Consistent with experimental measurements, the simulations captured the following trend for the H2–metal interaction strength: Ni-MOF-74 > Co-MOF-74 > Mg-MOF-74 > Zn-MOF-74. The calculations revealed that s...

Understanding Hydrogen Sorption in In-soc-MOF: A Charged Metal-Organic Framework with Open-Metal Sites, Narrow Channels, and Counterions

Abstract: Grand canonical Monte Carlo (GCMC) simulations of hydrogen sorption were performed in In-soc-MOF, a charged metal–organic framework (MOF) that contains In3O trimers coordinated to 5,5′-azobis(1,3-benzenedicarboxylate) linkers. The MOF contains nitrate counterions that are located in carcerand-like capsules of the framework. This MOF was shown to have a high hydrogen uptake at 77 K and 1.0 atm. The simulations were performed with a potential that includes explicit many-body polarization interactions, which were important for modeling gas sorption in a charged/polar MOF such as In-soc-MOF. The simulated hydrogen sorption isotherms were in good agreement with experiment in this challenging platform for modeling. The simulations predict a high initial isosteric heat of adsorption, Qst, value of about 8.5 kJ mol–1, which is in contrast to the experimental value of 6.5 kJ mol–1 for all loadings. The difference in the Qst behavior between experiment and simulation is attributed to the fact that, in experimental ...

Investigating H2 Sorption in a Fluorinated Metal–Organic Framework with Small Pores Through Molecular Simulation and Inelastic Neutron Scattering

Abstract: Simulations of H2 sorption were performed in a metal–organic framework (MOF) consisting of Zn2+ ions coordinated to 1,2,4-triazole and tetrafluoroterephthalate ligands (denoted [Zn(trz)(tftph)] in this work). The simulated H2 sorption isotherms reported in this work are consistent with the experimental data for the state points considered. The experimental H2 isosteric heat of adsorption (Qst) values for this MOF are approximately 8.0 kJ mol–1 for the considered loading range, which is in the proximity of those determined from simulation. The experimental inelastic neutron scattering (INS) spectra for H2 in [Zn(trz)(tftph)] reveal at least two peaks that occur at low energies, which corresponds to high barriers to rotation for the respective sites. The most favorable sorption site in the MOF was identified from the simulations as sorption in the vicinity of a metal–coordinated H2O molecule, an exposed fluorine atom, and a carboxylate oxygen atom in a confined region in the framework. Secondary sorption wa...

Inelastic Neutron Scattering and Theoretical Studies of H2 Sorption in a Dy(III)-Based Phosphine Coordination Material

Abstract: A combined inelastic neutron scattering (INS) and theoretical study of H2 sorption was performed in PCM-16, a phosphine coordination material (PCM) with the empirical formula [(CH3)2NH2][Dy2(tctpo)2(O2CH)] (tctpo = tris(p-carboxylato)triphenylphosphine oxide). INS measurements at different loadings of H2 revealed a peak occurring at low rotational tunnelling energies (ca. 5–8 meV), which corresponds to a high barrier to rotation and, therefore, a strong interaction with the host. Molecular simulations of H2 sorption in PCM-16 revealed that the H2 molecules sorbed at two main sites in the material: (1) the (CH3)2NH2+ counterions and (2) within the small pores of the framework. Two-dimensional quantum rotation calculations revealed that the peak occurring from approximately 5–8 meV in the INS spectra for PCM-16 is associated with sorption onto the (CH3)2NH2+ ions. These counterions provide for the strongest H2 sorption sites in the material, which corresponds to an isosteric heat of adsorption (Qst) value o...

Encapsulation of paclitaxel into a bio-nanocomposite. a study combining inelastic neutron scattering to thermal analysis and infrared spectroscopy

Abstract: The anticancer drug paclitaxel was encapsulated into a bio-nanocomposite formed by magnetic nanoparticles, chitosan and apatite. The aim of this drug carrier is to provide a new perspective against breast cancer. The dynamics of the pure and encapsulated drug were investigated in order to verify possible molecular changes caused by the encapsulation, as well as to follow which interactions may occur between paclitaxel and the composite. Fourier transformed infrared spectroscopy, thermal analysis, inelastic and quasi-elastic neutron scattering experiments were performed. These very preliminary results suggest the successful encapsulation of the drug.

Hydrogen Storage Materials

Abstract: An eventual realization of a Hydrogen Economy requires working solutions in three fundamental areas, namely hydrogen production, hydrogen storage, and fuel cells, in addition to the development of an extensive, new infrastructure. While neutron scattering experiments and the associated techniques of analysis have been of utility in all three of these research areas, they have had by far the most significant impact on the development and understanding of materials for hydrogen storage applications. This chapter examines some of these contributions.