Combined Theoretical and Experimental Investigation of CO Adsorption on Coordinatively Unsaturated Sites in CuBTC MOF
Abstract
The adsorption of CO in metalorganic framework CuBTC material is investigated by a combination of theoretical and experimental approaches. The adsorption enthalpy of CO on CuBTC determined experimentally to be -29 kJ?mol-1 at the zero-coverage limit is in very good agreement with the adsorption enthalpy calculated at the combined DFTab initio level with the periodic model.
Calculations show that polycarbonyl complexes cannot be formed on regular coordinatively unsaturated sites in CuBTC. Experimental IR spectra of the CO probe molecule adsorbed in CuBTC are interpreted based on calculated CO stretching frequencies.
Calculations show that long-range interactions are insignificant for the CO/CuBTC system and that this system can be accurately modeled with just a Cu2(HCOO)4 cluster model of the paddle wheel. The reliability of various methods for the description of CO interaction with the Cu2+ site in CuBTC is discussed based on the experimental results and accurate coupled-cluster calculations.
It is shown that standard exchange-correlation functionals do not provide a reliable description of CO interaction with coordinatively unsaturated Cu2+ sites in CuBTC.