Interaction between ions and substituted buckybowls: A comprehensive computational study

Abstract

Complexes formed by substituted buckybowls derived from corannulene and sumanene with sodium cation or chloride anion have been computationally studied by using a variety of methods. Best results have been obtained with the SCS-MP2 method extrapolated to basis set limit, which reproduces the highest-level values obtained with the MP2.X method. All bowls form stable complexes with chloride anion, with stabilities ranging from -6 kcal/mol in the methylated corannulene derivative to -45 kcal/mol in the CN-substituted sumanene. The opposite trend is observed in sodium complexes, going from deeply attractive complexes with the methylated derivatives (-36 kcal/mol with sumanene derivative) to slightly repulsive ones in the CN-substituted bowls (2 kcal/mol in the corannulene derivative). Anion complexes are stabilized by large electrostatic interactions combined with smaller though significant dispersion and induction contributions. Conversely, cation complexes are stabilized by large induction contributions capable of holding together the bowl and the cation even in cases where the electrostatic interaction is repulsive. The effect of substitution is mainly reflected on changes in the molecular electrostatic potential of the bowl and, thus, in the electrostatic contribution to the interaction. Therefore, the variations in the stability of the complexes on substitution could be roughly predicted just considering the changes in the electrostatic interaction. However, other contributions also register changes mainly as a consequence of displacements on the position of the ion at the minimum, so the accurate prediction of the stability of this kind of complexes requires going further than the electrostatic approach.

Dissecting the concave–convex π‐π interaction in corannulene and sumanene dimers: SAPT(DFT) analysis and performance of DFT dispersion‐corrected methods

“…Corannulene has a bowl depth amounting to 0.86 Å, in agreement with previous calculations and the X‐ray structure . Sumanene is a deeper bowl, with a depth of 1.11 Å to the carbon atoms in the rim of the hexagonal rings (0.86 Å to the pentagonal rings), also in agreement with previous results in the literature . The inclusion of sulphur atoms in sumanene to give sumaS leads to a significant flattening of the bowl, reducing the depth to just 0.68 Å.…”

“…The bowl asymmetry is clearly revealed by the molecular electrostatic potentials (MEPs) plotted in Figure , showing the MEPs from below (convex face) and from above (concave face) the bowls, varying from −15 (red) to 15 (blue) kcal/mol on isodensity surfaces of 0.002 a.u. As in previous work, corannulene and sumanene have negative MEP on the central region of both sides of the bowl, although slightly more negative on the convex face. While corannulene shows a negative surface inside the bowl and positive on the rim, in sumanene the negative surface of the convex side is disrupted by positive regions corresponding to the CH 2 groups.…”

How carbo-benzenes fit molecules in their inner core as do biologic ion carriers?

“…Comparing entries 1 and 2 in Table 3, the effect of dispersion on the geometries turns out to be quantitatively not that relevant, by less than 1 kcal/mol. In comparison with previous results of the interaction of cations with carbon-based structures [33], MP2 and CCSD [34] give more favourable interactions of the potassium ion with the empty carbo-benzene by 3.0 and 0.4 kcal/mol only, respectively, taking into account the energy values in solution. Moreover, the intermolecular basis set superposition error (BSSE) is not very relevant since it is just 0.9 kcal/mol with potassium ion, for the 6-311G(d,p) basis set.…”

On the interaction between the imidazolium cation and aromatic amino acids. A computational study

“…5,7 The same could be said of the hydrogen bond-like interactions between X-H groups and aromatic rings, mostly involving OH, NH and CH bonds. 8,10 Finally, the interaction between aromatic rings and charged species is controlled by the combination of electrostatic and induction contributions in cation···π contacts, 9,[11][12][13][14] whereas the role of induction is less significant when anions are involved. 14,15 In any case, the interaction between a cation and a polarisable π cloud is usually strong in the gas phase, being a contact frequently observed in biological systems.…”

“…8,10 Finally, the interaction between aromatic rings and charged species is controlled by the combination of electrostatic and induction contributions in cation···π contacts, 9,[11][12][13][14] whereas the role of induction is less significant when anions are involved. 14,15 In any case, the interaction between a cation and a polarisable π cloud is usually strong in the gas phase, being a contact frequently observed in biological systems. [16][17][18][19][20] However, the strength of the cation···π interactions can be modulated by changes on the environment or on the nature of the aromatic ring involved.…”