London Dispersion Governs the Interaction Mechanism of Small Polar and Nonpolar Molecules in Metal–Organic Frameworks

Abstract

In this work, we investigate the adsorption of chlorinated methanes (CH x Cl4–x , x = 0–4) in a representative layer-pillar metal–organic framework, the flexible MOF Ni2(ndc)2(dabco) (ndc = 2,6-naphthalene-dicarboxylate, dabco = 1,4-diazabicyclo-[2.2.2]-octane), also known as DUT-8­(Ni). The guest molecules show a systematic increase of polarizability with increasing number of chlorine atoms, whereas the dipole moment exceeds 2 debye for x = 2 and 3. Our ligand field molecular mechanics simulations show that, at first, counter-intuitively, the host–guest interactions are mainly characterized by London dispersion despite the molecular dipole moments reaching magnitudes as large as water. This highlights the importance of London dispersion interactions in the description of host–guest interactions.

Tailoring adsorption induced switchability of a pillared layer MOF by crystal size engineering

“…In order to reduce the stress during solvent removal, DMF was exchanged with dichloromethane (DCM) before desolvation under reduced pressure at 423 K during 16 h (procedure b). DCM is a molecule with a smaller kinetic diameter (4.70 Å) 63 , smaller dipole moment (1.62 D) 64 and low boiling point (312.6 K), therefore, in comparison to DMF, it should be easier to remove. According to PXRD (Figure 4), the desolvation of the macro-sized 1b and micron-sized crystals 2b triggers the structural transformation from op to cp phase, in which the framework undergoes a significant shearing to minimize the amount of void space.…”

“…However, as the size differs considerably, significant differences in maximal loadings per formula unit of MOF (nmax) can be estimated (Table 1). 63 Hence, the total adsorption energy (nmaxEads) per Zn2(2,6ndc)2dabco formula unit (fu) of MOF decreases continuously from chloromethane to tetrachloromethane (Tab. 1).…”

Integration of High‐Performance Cost‐Effective Copper‐Metal‐Organic‐Nanocluster‐based Gate Dielectric for Next‐Generation CMOS Applications

“…Under the dynamically applied bias, the inherent dipole moments align themselves in the direction of the external stimuli applied electric fields. [ 66 ] Figure 6d shows the energy band diagram of Cu‐MOCs based on Al/Cu‐MOCs/Si MIS‐CAP structures. The actual band positions of MOCs differ with the metal centers and organic ligands systems.…”

Investigation of CO2 Orientational Dynamics through Simulated NMR Line Shapes

“…We employ our previously published Ligand-Field Molecular Mechanics (LFMM) simulation setup for DUT-8(Ni). [34,35] We perform three types of MD simulations: 1) CO2 in the rigid A conformer of DUT-8(Ni) using a fully flexible cell (NσT ensemble); 2) CO2 in the B conformer with a fully flexible cell (NσT ensemble); 3) CO2 in the B conformer with a fixed cell (NVT ensemble) in the op state. For details of the LFMM parametrization see ref [34] , details of the MD simulations are given in the Supporting Information and adhere to the previous publications.…”