Three-dimensional metal-organic framework with highly polar pore surface: H2 and CO2 storage characteristics.
A three-dimensional (3D) pillared-layer metal-organic framework, [Cd(bipy)(0.5)(Himdc)](DMF)](n) (1), (bipy =4,4'-bipyridine and Himdc = 4,5-imidazoledicarboxylate) has been synthesized and structurally characterized. The highly rigid and stable framework contains a 3D channel structure with highly polar pore surfaces decorated with pendant oxygen atoms of the Himdc linkers. The desolvated framework [Cd(bipy)(0.5)(Himdc)](n) (1') is found to exhibit permanent porosity with high H(2) and CO(2) storage capacities. Two H(2) molecules occluded per unit formula of 1' and the corresponding heat of H(2) adsorption (ΔH(H2)) is about ∼9.0 kJ/mol. The high value of ΔH(H2) stems from the preferential electrostatic interaction of H(2) with the pendent oxygen atoms of Himdc and aromatic bipy linkers as determined from first-principles density functional theory (DFT) based calculations. Similarly, DFT studies indicate CO(2) to preferentially interact electrostatically (C(δ+)···O(δ-)) with the uncoordinated pendent oxygen of Himdc. It also interacts with bipy through C-H···O bonding, thus rationalizing the high heat (ΔH(CO2) ∼ 35.4 kJ/mol) of CO(2) uptake. Our work unveiled that better H(2) or CO(2) storage materials can be developed through the immobilization of reactive hetero atoms (O, N) at the pore surfaces in a metal-organic framework.
Molecular Materials Laboratory, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India.
Kolleboyina
K
Jayaramulu
Sandeep Kumar
SK
Reddy
Arpan
A
Hazra
Sundaram
S
Balasubramanian
Tapas Kumar
TK
Maji
D000327:Adsorption; D002104:Cadmium / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006859:Hydrogen / Q000737:chemistry*; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011789:Quantum Theory; D013499:Surface Properties
D009942:Organometallic Compounds; D002104:Cadmium; D002245:Carbon Dioxide; D006859:Hydrogen