Interaction of Small Gases with the Unsaturated Metal Centers of the HKUST-1 Metal Organic Framework

Abstract

The interactions of CO, CO 2 , OCS, SO 2 , NO, NO 2 , N 2 O, NH 3 , PH 3 , and other small molecules with the undercoordinated metal centers of the HKUST-1 metal organic framework are studied by means of density functional theory. These molecules are potentially harmful for humans and the environment and are widely studied because of their spectroscopic properties. In this work, the energetic and vibrational characteristics of the adsorbed species are calculated. Adsorption energies on the Cu 2+ sites of the paddlewheel have been calculated, and the order is:The results show that the interactions can be classified into three categories: (1) weak physisorption, (2) polarization and electrostatics, and (3) strong acid−base. Moreover, interesting vibrational properties are calculated especially for carbonyl sulfide and dinitrogen monoxide, which can be bound via two different configurations on the metal atoms. The vibrational modes are shifting in different directions depending on the binding way of the molecule; e.g., the symmetric stretching of OCS is shifted by +17 or −16 cm −1 when bound via the oxygen or the sulfur atom, respectively.

Multifunctional metal–organic frameworks: from academia to industrial applications

“…152 To tackle these phenomena, several research groups have reported the development and use of MOF structures with potential to interact, and consequently remove, many hazardous chemicals.…”

Molecular simulation of adsorption of NO and CO2 mixtures by a Cu-BTC metal organic framework

“…The binding energy of CO 2 was higher compared with the results calculated by Farrusseng [23]. The error was largely due to another gas existed in the system and caused by different representative fragment, function and basis set.…”

“…Much research focused on NO delivery materials for medical devices to prevent thrombosis formation [22]. Despite their harmfulness for humans and the environment, they are vital for life as signaling molecules and are produced endogenously by the body [23]. High concentration of blood CO 2 levels occurs in patients with respiratory diseases such as COPD [24].…”

“…In theoretical work, Ding et al [31] adopted Grand canonical Monte Carlo (GCMC) analysis to study the adsorption isotherms of a range of small gaseous molecules that could impact CO 2 adsorption in MOFs and used a density functional theory (DFT) method to calculate the binding energy. Supronowicz et al [23] used DFT to investigate NO and CO 2 as independent components interacting with the metal center in Cu-BTC. Despite these works, research into the microscopic nature of the interaction between MOFs and NO and CO 2 molecules is still limited.…”

Density functional theory meta-GGA + U study of water incorporation in the metal-organic framework material Cu-BTC

“…A recent X-ray powder diffraction refinement, [21] on the other hand, shows evidence for 2.3 bound water molecules per Cu atom, in three different partially occupied binding sites, although it was not possible to determine the hydrogen positions for these water molecules. Previous electronic structure calculations and molecular simulations have generally investigated the structure of H 2 O in Cu-BTC only up to one H 2 O per Cu ion, [22][23][24][25] in which case one water molecule binds to each Cu position, with the water oxygen atom (O W ) closest to the Cu. In this work, we use density functional theory at the "meta-GGA + U" level to investigate the structure of water absorption in Cu-BTC up to 3.5 H 2 O per Cu.…”