Anion Recognition by Organometallic Calixarenes: Analysis from Relativistic DFT Calculations

The physical nature
of the noncovalent interactions involved in
anion recognition was investigated in the context of metalated calix[4]­arene
hosts, employing Kohn–Sham molecular orbital (KS-MO) theory,
in conjunction with a canonical energy decomposition analysis, at
the dispersion-corrected DFT level of theory. Computed data evidence
that the most stable host–guest bonding occurs in ruthenium
complexed hosts, followed by technetium and molybdenum metalated macrocyclic
receptors. Furthermore, the guest’s steric fit in the host
scaffold is a selective and crucial criterion to the anion recognition.
Our analyses reveal that coordinated charged metals provide a larger
electrostatic stabilization to anion recognition, shifting the calixarenes
cavity toward an electron deficient acidic character. This study contributes
to the design and development of new organometallic macrocyclic hosts
with increased anion recognition specificity.