TY - BOOK

T1 - Modeling of metal-organic frameworks for optical applications

AU - Treger, Marvin

PY - 2023

Y1 - 2023

N2 - Metal-organic frameworks (MOFs) are an important class of porous hybrid materials. They consist of metal ions or metal-oxo clusters forming the so-called inorganic building units connected by organic ligands acting as linker molecules leading to an intrinsic porosity of the framework. MOFs have been discussed intensively with regard to classical applications of porous materials like catalysis and gas separation. In this work, a different aspect is focused, namely the use of MOFs as optical materials. One fundamental property in this respect is the refractive index (RI). To ensure the reliable and precise calculation of the RI of MOFs a novel ab initio simulation protocol was developed in this work. By applying density functional theory (DFT), accurate models of MOF crystal structures were prepared and the optical properties were calculated precisely. Starting with the well-known UiO-66 MOF and its established nitro- and aminofunctionalized derivatives UiO-66-NO2 and UiO-66-NH2, this simulation protocol was used to calculate the electronic structures and the corresponding optical properties. Furthermore, the incorporation of “push–pull” linkers into the UiO-66 framework was studied to allow a further tuning of the RI of the parent UiO-66 MOF. In this context, a novel UiO-66 analogue denoted as UiO-66-(NH2,NO2) was presented. In addition, the use of halogenated linkers yielding the well-known monohalogenated UiO-66 derivatives denoted as UiO-66-X (𝑋 = F, Cl, Br, I) was studied. To obtain high RI values while preserving the transparency in the visible spectral region, a novel dihalogenated UiO-66 derivative denoted as UiO-66-I2 was introduced. The simulation protocol developed in the first part of this work allows a detailed study of the electronic structure of MOFs and a better understanding how the the various modular components of a MOF influence its RI. This protocol is computationally demanding. As a consequence, a second, more efficient simulation protocol was presented allowing the screening of MOFs with regard to their RI. This simulation protocol is based on a fragmentation scheme for MOFs allowing the separate calculation of the polarizability of the modular components of MOFs using DFT. These polarizabilities were used to compute the total polarizability of a MOF and subsequently the corresponding RI by applying the Lorenz-Lorentz equation.

AB - Metal-organic frameworks (MOFs) are an important class of porous hybrid materials. They consist of metal ions or metal-oxo clusters forming the so-called inorganic building units connected by organic ligands acting as linker molecules leading to an intrinsic porosity of the framework. MOFs have been discussed intensively with regard to classical applications of porous materials like catalysis and gas separation. In this work, a different aspect is focused, namely the use of MOFs as optical materials. One fundamental property in this respect is the refractive index (RI). To ensure the reliable and precise calculation of the RI of MOFs a novel ab initio simulation protocol was developed in this work. By applying density functional theory (DFT), accurate models of MOF crystal structures were prepared and the optical properties were calculated precisely. Starting with the well-known UiO-66 MOF and its established nitro- and aminofunctionalized derivatives UiO-66-NO2 and UiO-66-NH2, this simulation protocol was used to calculate the electronic structures and the corresponding optical properties. Furthermore, the incorporation of “push–pull” linkers into the UiO-66 framework was studied to allow a further tuning of the RI of the parent UiO-66 MOF. In this context, a novel UiO-66 analogue denoted as UiO-66-(NH2,NO2) was presented. In addition, the use of halogenated linkers yielding the well-known monohalogenated UiO-66 derivatives denoted as UiO-66-X (𝑋 = F, Cl, Br, I) was studied. To obtain high RI values while preserving the transparency in the visible spectral region, a novel dihalogenated UiO-66 derivative denoted as UiO-66-I2 was introduced. The simulation protocol developed in the first part of this work allows a detailed study of the electronic structure of MOFs and a better understanding how the the various modular components of a MOF influence its RI. This protocol is computationally demanding. As a consequence, a second, more efficient simulation protocol was presented allowing the screening of MOFs with regard to their RI. This simulation protocol is based on a fragmentation scheme for MOFs allowing the separate calculation of the polarizability of the modular components of MOFs using DFT. These polarizabilities were used to compute the total polarizability of a MOF and subsequently the corresponding RI by applying the Lorenz-Lorentz equation.

U2 - 10.15488/15766

DO - 10.15488/15766

M3 - Doctoral thesis

CY - Hannover

ER -