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

Abstract

The hydrogen, carbon dioxide, and carbon monoxide gas adsorption and storage capacity of lithium‐decorated cyclopropane ring systems were examined with quantum chemical calculations at density functional theory, DFT M06‐2X functional using 6‐31G(d) and cc‐pVDZ basis sets. To examine the reliability of M06‐2X DFT functional, a few representative systems are also examined with complete basis set CBS‐QB3 method and CCSD‐aug‐cc‐pVTZ level of theory. The cyclopropane systems can bind to one Li+ ion; however, the corresponding the methylated systems can bind with two Li+ ions. The cyclopropane systems can adsorb six hydrogen molecules with an average binding energy of 3.8 kcal/mol. The binding free energy (ΔG) values suggest that the hydrogen adsorption process is feasible at 273.15 K. The calculation of desorption energies indicates the recyclable property of gas adsorbed complexes. The same number of CO2 and CO gas molecules can also be adsorbed with an average binding energy of −14.4 kcal/mol and −10.7 kcal/mol, respectively. The carbon dioxide showed ~3–4 kcal/mol better binding energy as compared to carbon monoxide and hence such designed systems can function as a potential candidate for the separation of these flue gas molecules. The nature of interactions in complexes was examined with atoms in molecules analysis revealed the electrostatic nature for the interaction of Li+ ion with cyclopropane rings. The chemical hardness and electrophilicity calculations showed that the gas adsorbed complexes are rigid and therefore robust as gas storage materials.

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

“… 20 , 25 , 32 , 33 Many molecular systems have been examined for hydrogen adsorption such as metal-decorated benzene, cyclohexane, adamantane, cyclopropane systems, and B- and N-substituted carbon rings. 34 − 36 Such molecular systems can be altered with appropriate modifications or decorated with metal ions for the use of flue gas separation. Prismane is known to be an interesting molecule with unusual bonding features such as cyclopropanes.…”

“…The Li + -ion binding with the prismane molecule (−35.5 kcal/mole) was found to be superior to the binding with the cyclopropane bent bonds (−32.2 kcal/mole) at the same level of theory. 36 The mode of binding differs for prismane as the metal ion binds on the rectangular face, whereas cyclopropanes bind the Li + ion with the edge −C−C− bonds. The binding affinity trend of Li + , K + , Mg 2+ , and Ca 2+ ions with the prismane molecule was examined with molecular electrostatic potential (MESP) surfaces.…”

“…A variety of materials have been developed for flue gas separation such as zeolites, MOFs, polymers, and carbon-based materials such as activated carbon, graphene, and potassium-tethered carbons . Recently, metal-ion doping is used as a strategy for improving the gas adsorption capacity of materials. ,,, Many molecular systems have been examined for hydrogen adsorption such as metal-decorated benzene, cyclohexane, adamantane, cyclopropane systems, and B- and N-substituted carbon rings. − Such molecular systems can be altered with appropriate modifications or decorated with metal ions for the use of flue gas separation. Prismane is known to be an interesting molecule with unusual bonding features such as cyclopropanes .…”

“…Therefore, the greater permanent electrical quadruple moment contributes to the higher adsorption of CO 2 gas molecules compared to N 2 and CH 4 gas. The metal-ion-decorated organic systems have been examined for different applications using experimental and computational techniques. − ,− Nonetheless, it is also important to gauge the role of counterions in such systems toward their efficacy in the gas adsorption process. We have examined the gas adsorption capacity with a representative system such as the Mg 2+ -decorated prismane molecule in the presence of chloride ions as counterions.…”

Hydrogen storage capacity of Be2(NLi)2cluster with ultra‐shortberyllium–berylliumdistance

“…metal aromatic cluster, 20 namely, Be 3 M 2 , Mg 3 M 2 , Al 4 M 2 (M = Li, Na, K). In 2012, Giri et al designed a star like C 6 Li 6 cluster as 6-12 hydrogen storage material.…”