Probing the bent bonds in cyclopropane systems for gas storage and separation process: A computational study

Metal ion-decorated hexasilaprismane and its derivative as a molecular container for the separation of CO2 from flue gas molecules: a computational study

The electronic structure of hexasilaprismane (HSP) was examined with different computational techniques to elucidate the bonding features and the electrostatic surface potential of HSP. The carbon dioxide adsorption and separation capacities of metal-ion-decorated hexasilaprismane (HSP) were examined with DFT and CBS-QB3. Furthermore, the 1,2,3,4,5,6-hexaphenylprismasilane (HPPS) molecule was examined for its binding with metal ions and gas adsorption capacity. The Mg²⁺ ion complexed HPPS molecule adsorbs 15CO₂ molecules with an average binding free energy of -0.98 eV per molecule. The calculated gravimetric densities of 45.1 and 48.4 wt% show that these systems can be employed for CO₂ capture. The substantial difference in the affinity of the designed systems for CO₂ gas molecules compared to N₂ and CH₄ molecules show the potential of the systems for CO₂ separation from N₂ and CH₄ gas molecules.

Computational Study on Metal-Ion-Decorated Prismane Molecules for Selective Adsorption of CO2 from Flue Gas Mixtures

Selective adsorption of CO₂ from flue gas is extremely significant because of its increasing concentration in air and its deleterious effect on the environment. In this work, we have explored metal-ion-bound prismane molecules for selective CO₂ adsorption from the flue gas mixture. The Ca²⁺-bound prismane complex exhibits superior CO₂ selectivity and adsorption capacity. The calculated binding energy and molecular electrostatic potential (MESP) analysis showed that the rectangular face of prismane binds strongly with metal ions as compared to its triangular face. The CBS-QB3 and density functional theory-based functional M06-2X/6-311+G(d) calculations show that the prismane molecule can bind to one Li⁺, K⁺, Mg²⁺, and Ca²⁺ ion with favorable binding energy. The metal-ion-bound prismane complexes have been examined for their CO₂, N₂, and CH₄ adsorption capacity. Prismane-Ca²⁺ can bind with six CO₂ molecules strongly with an average binding energy of -18.1 kcal/mole as compared to six N₂ (-12.6) and five CH₄ (-13.4) gas molecules. The gravimetric density calculated for the CO₂-adsorbed prismane-Ca²⁺ complex has been found to be 69.1 wt %. The discrete hydrocarbon structure for selective separation of CO₂ is rare in the literature and can have potential applications for cost-effective CO₂ capture from the flue gas mixture.