2 research outputs found
Solid-State Gas Adsorption Studies with Discrete Palladium(II) [Pd<sub>2</sub>(L)<sub>4</sub>]<sup>4+</sup> Cages
The need for effective CO2 capture systems remains high, and due to their tunability, metallosupramolecular architectures are an attractive option for gas sorption. While the use of extended metal organic frameworks for gas adsorption has been extensively explored, the exploitation of discrete metallocage architectures to bind gases remains in its infancy. Herein the solid state gas adsorption properties of a series of [Pd2(L)4]4+ lantern shaped coordination cages (L = variants of 2,6âbis(pyridinâ3âylethynyl)pyridine), which had solvent accessible internal cavities suitable for gas binding, have been investigated. The cages showed little interaction with dinitrogen gas but were able to take up CO2. The best performing cage reversibly sorbed 1.4â
mol CO2 per mol cage at 298â
K, and 2.3â
mol CO2 per mol cage at 258â
K (1â
bar). The enthalpy of binding was calculated to be 25â35â
kJâmolâ1, across the number of equivalents bound, while DFT calculations on the CO2 binding in the cage gave ÎE for the cageâCO2 interaction of 23â28â
kJâmolâ1, across the same range. DFT modelling suggested that the binding mode is a hydrogen bond between the carbonyl oxygen of CO2 and the internally directed hydrogen atoms of the cage