Interaction between anions and substituted molecular bowls

Abstract

Complexes formed by anions and substituted molecular bowls were studied by means of computational methods. The bowls consisted of corannulene molecules substituted with five or ten F, Cl, or CN groups, whereas Cl(-), Br(-) and BF(4)(-) were the anions considered. Substitution with F, Cl and CN hardly affects the geometry of the bowl, but produces an inversion of the molecular electrostatic potential of the bowls, which becomes positive over the two faces of the bowl, therefore interacting favorably with anions. In all cases considered, the most stable complex presents the anion interacting with the concave side of the bowl. The strength of the interaction roughly follows the values of molecular electrostatic potential, being more stable as more positive is the potential. The preference of anions to interact with the concave side of the bowls has its origin in stronger electrostatic and dispersion interactions. Though the solvent produces an important decrease in the stability of the complexes, the results suggest the possibility of employing these substituted buckybowls as anion receptors with a preferential concave complexation, especially for large anions.

Interaction between ions and substituted buckybowls: A comprehensive computational study

“…[2,3,11,12,14] Also, anionÁÁÁp interactions between an anion and an electron-deficient aromatic system have recently aroused interest. [20,25] It has also been shown that aromaticity can change on ion complexation by aromatic species. [20,21] However, it has been shown that in cationÁÁÁp systems, the role played by polarization can be important, especially in extended aromatic systems, [22][23][24] where it can be the main responsible of the stability of a cationÁÁÁp complex.…”

“…[20,21] However, it has been shown that in cationÁÁÁp systems, the role played by polarization can be important, especially in extended aromatic systems, [22][23][24] where it can be the main responsible of the stability of a cationÁÁÁp complex. [18,20,24,25] Polycyclic aromatic hydrocarbons (PAHs) have attracted much interest related to possible application to materials science. [20,25] It has also been shown that aromaticity can change on ion complexation by aromatic species.…”

“…[39,40] The simplest of these bowls, corannulene C 20 H 10 , has already been considered in different studies to determine its structure, barrier for inversion and also its capability for coordinating cations. [24,25] The other smallest bowl that can be mapped onto C 60 is sumanene C 21 H 12 , quite recently synthesized and which corresponds to a bowl with a six-carbon ring at the bottom. The MEP of corannulene is more negative by the convex face so coordination of cations is mostly favored by this face.…”

“…[52] The coordination of metals to this bowl has also been considered showing similar characteristics as those observed for corannulene. [25] Even though this kind of ionÁÁÁp complex is expected to be stabilized mainly by electrostatics, the interaction in these systems is quite difficult to describe. [24,[39][40][41]44,45,[47][48][49]51] However, in a previous work by our group, it has been shown that corannulene substituted with electron-withdrawing groups is able to form stable complexes with anions.…”

Syntheses and Properties of Buckybowls Bearing Electron-withdrawing Groups

“…All studied compounds were shown to interact favorably with the anions Cl ¹ , Br ¹ , and BF 4 ¹ via the conjugated system, preferentially on the concave side. 32 Complementarily, Josa et al studied dimers of corannulene bearing electron-withdrawing groups for fullerene recognition. 33 Dos Santos et al investigated 13 fluorinated corannulenes ( Figure 5) by density functional theory calculations.…”