Computational details
MPBCP, [La-MPBCP]+3 and La-MPBCP complexes were optimized using the density functional theory. Calculations in this paper were performed with the Perdew-Burke-Ernzerhof (PBE0-D3)39-40 functional and the def2-TZVP basis set,41 using the Gaussian 09 program.42 In order to characterize all optimized structures, we have computed their vibrational modes at the same level of theory. Geometries from local minima were used to carry out their respective NBO analysis, at the same level of theory.43 The band gap of the system was calculated from the difference between HOMO and LUMO orbitals. The adsorption energy, Eads , is defined as the difference between the sum of the energy of the isolated molecule gas and of [La-MPBCP]+3 and La-MPBCP complex and the energy of the system with a bonded gas molecule. Adsorption energy (E ads) of different systems are calculated with the following equation:
Eads (gas molecule) = E ([MPBCP] -gas molecule) - (E [MPBCP] + E gas molecule)
Eads (gas molecule) = E([La-MPBCP]+3 -gas molecule) - (E[La-MPBCP]+3 + E gas molecule)
Eads (gas molecule) = E (La-MPBCP -gas molecule) - (E La-MPBCP + E gas molecule)
Where E (E La-MPBCP or [La-MPBCP]+3-gas molecule) is the total energy of the system of E [La-MPBCP]+3 or ELa-MPBCP and gas molecules, and E[La-MPBCP]+3, La-MPBCP and E gas molecule are the total energies of the functionalized structure with lanthanum and a molecule of gas present, respectively.
The quantum molecular descriptors for [La-MPBCP]+3, La-MPBCP consist of ionization potential (I), electron affinity (A), global hardness (η),44 electronegativity (χ), electronic chemical potential (μ),45 electrophilicity index (ω)46 and chemical softness (S) are calculated according to follows equations: I = −EHOMO,A = −ELUMO, η = (I – A)∕2, χ= I + A∕2, µ = −(I + A)∕2, ω= ‑ µ2∕2η and S = 1∕2­η
All generated files from Gaussian 09 were analyzed with the Chemcraft program v1.8