Premium
Solid‐State Gas Adsorption Studies with Discrete Palladium(II) [Pd 2 (L) 4 ] 4+ Cages
Author(s) -
Preston Dan,
White Keith F.,
Lewis James E. M.,
Vasdev Roan A. S.,
Abrahams Brendan F.,
Crowley James D.
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201701477
Subject(s) - chemistry , adsorption , enthalpy , cage , pyridine , binding energy , hydrogen bond , palladium , hydrogen , sorption , solvent , hydrogen storage , crystallography , molecule , thermodynamics , organic chemistry , catalysis , atomic physics , physics , mathematics , combinatorics
The need for effective CO 2 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 [Pd 2 ( L ) 4 ] 4+ lantern shaped coordination cages ( L = variants of 2,6‐bis(pyridin‐3‐ylethynyl)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 CO 2 . The best performing cage reversibly sorbed 1.4 mol CO 2 per mol cage at 298 K, and 2.3 mol CO 2 per mol cage at 258 K (1 bar). The enthalpy of binding was calculated to be 25–35 kJ mol −1 , across the number of equivalents bound, while DFT calculations on the CO 2 binding in the cage gave Δ E for the cage–CO 2 interaction of 23–28 kJ mol −1 , across the same range. DFT modelling suggested that the binding mode is a hydrogen bond between the carbonyl oxygen of CO 2 and the internally directed hydrogen atoms of the cage.