Impact of ligands on CO2 adsorption in metal-organic frameworks: First principles study of the interaction of CO2 with functionalized benzenes. II. Effect of polar and acidic substituents.
J CHEM PHYS
, Article 044705. 10.1063/1.3276105.
Intermolecular interactions between the CO2 molecule and a range of functionalized aromatic molecules have been investigated using density functional theory. The work is directed toward the design of linker molecules which could form part of new metal-organic framework materials with enhanced affinity for CO2 adsorption at low pressure. Here, the focus was on the effect of introducing polar side groups, and therefore functionalized benzenes containing - NO2, - NH2, - OH, - SO3H, and - COOH substituents were considered. The strongest types of intermolecular interactions were found to be: (i) between lone pair donating atoms (N,O) of the side groups and the C of CO2 (enhancement in binding energy of up to 8 kJ mol(-1) compared to benzene); and (ii) hydrogen bond interactions between acidic protons (of COOH and SO3H groups) and CO2 oxygen (enhancement of 3-4 kJ mol(-1)). Both of these types of interaction have the effect of polarizing the CO2 molecule. Weaker types of binding include hydrogen-bond-like interactions with aromatic H and pi-quadrupole interactions. The strongest binding is found when more than one interaction occurs simultaneously, as in C6H5SO3H and C6H5COOH, where simultaneous lone pair donation and H-bonding result in binding energy enhancements of 10 and 11 kJ mol(-1), respectively.
|Title:||Impact of ligands on CO2 adsorption in metal-organic frameworks: First principles study of the interaction of CO2 with functionalized benzenes. II. Effect of polar and acidic substituents|
|Keywords:||ab initio calculations, adsorption, binding energy, bonds (chemical), carbon compounds, density functional theory, organic compounds, ZEOLITIC IMIDAZOLATE FRAMEWORKS, MOLECULAR SIMULATION, CARBON-DIOXIDE, MIL-53 AL, PORE-SIZE, HYDROGEN, METHANE, DESIGN, DIFFUSION, ENERGIES|
|UCL classification:||UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Maths and Physical Sciences
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