An Interplay of Cooperativity between Cation⋅⋅⋅π, Anion⋅⋅⋅π and CH⋅⋅⋅Anion Interactions

Abstract

Mixed cation (Li(+), Na(+) and K(+)) and anion (F(-), Cl(-), Br(-)) complexes of the aromatic π-surfaces (top and bottom) are studied by using dispersion-corrected density functional theory. The selectivity of the aromatic surface to interact with a cation or an anion can be tuned and even reversed by the electron-donating/electron-accepting nature of the side groups. The presence of a methyl group in the -OCH3, -SCH3, -OC2H5 in the side groups of the aromatic ring leads to further cooperative stabilization of the otherwise unstable/weakly stable anion⋅⋅⋅π complexes by bending of the side groups towards the anion to facilitate C-H⋅⋅⋅anion interactions. The cooperativity among the interactions is found to be as large as 100 kcal mol(-1) quantified by dissection of the three individual forces from the total interaction energy. The crystal structures of the fluoride binding tripodal and hexapodal ligands provide experimental evidence for such cooperative interactions.

The mutual interactions based on amphipathic tetraoxacalix[2]arene[2]triazine: recognition cases of anion and cation investigated by a computational study

“…Therefore, exploration of a highly efficient and stable host to recognize them is a raising considerable interest nowadays. 4,9,10,29,80,81 In this section, Na + and K + , as well as Mg 2+ and Ca 2+ are used as the target guest molecules to study their interaction natures and recognition characters with the 1. The geometry schemes of four cationÁ Á Áp complexes calculated are displayed in Fig.…”

“…[14][15][16][17][18][19][20][21][22] Two general types of anionÁ Á Áp interaction motifs were explored, one is typical anionÁ Á Áp interaction (attraction of an anion species to the centroid of an aromatic ring) and another is weak s-interaction (an anion is located over the periphery of an aromatic ring). 3,21 The anionÁ Á Áp noncovalent force, which is mainly dominated by electrostatic interaction or polarization, 12,14,23,24 has been shown to be energetically favorable by theoretical [24][25][26][27][28][29][30][31][32][33][34][35] and experimental studies. [34][35][36][37][38][39] Compared to numerous investigations of the anionÁ Á Áp interaction based on molecular recognition models that combine anionÁ Á Áp interactions with other noncovalent bond interactions (such as hydrogen bonding and halogen bonding), studies on the interactions of combining anions, p and cations are limited.…”

Interplay between Beryllium Bonds and Anion-π Interactions in BeR2:C6X6:Y− Complexes (R = H, F and Cl, X = H and F, and Y = Cl and Br)

“…Somewhat related to the anion-π interactions topic is the use of aromatic compounds as charge insulators. Many examples have been reported: Na + :C 6 H 6 :F − and Na + :C 6 F 6 :F − [13]; Li + :C 6 H 6 : F − ; K + :C 6 F 6 :Br − [14]; M + :C 6 H 3 F 3 :C 6 H 3 F 3 :X − [15]; M + :C 6 F 6 :Cr:C 6 H 6 :X − [16]; M + :C 6 H 6 :C 6 F 6 :X − [17]; cyclopropenyl + :C 6 H 6 :phenalenyl − [18]; Na + :1,3,5-triethynylbenzene: Cl − [19]; Li + :C 6 R 6 :F − , R = H, F, Cl, Br, OMe [20], and −Na + :C 6 H 3 F 3 :Cl − [21]. These have been extended to other insulators like hexafluoroethane [Na + :C 2 F 6 :Cl − ] [22], saturated cycloalkanes like Li + :adamantane:F − [23], cationic complexes like ZY 4 + :C 6 R 6 :YX, example: NH 4 + :C 6 H 6 :HF [24] as well as anionic complexes as XH:C 2 F 4 :Y − [25].…”

Hexaethylbenzene: A Sterically Crowded Arene and Conformationally Versatile Ligand

“…In the case of Li + ···(C 6 Et 6 )···F À (80;F igure 29), the calculated binding energy was 146 kcal mol À1 . [131] The well-established propensity of HEB to form adducts with threefold symmetry is also found for 1,3,5triethylbenzenea nd its derivatives. This is the basis of the widely used scaffolding approacht of orm species such as 81, reportedb yA nslyn et al, [132] whereby the 1,3,5-substituents are convergent, as in the previously mentioned study by Kilway and Siegel.…”

“…The presence of a cation on the other face of the HEB amplifies this effect leading to strong interactions with the anion. In the case of Li + ⋅⋅⋅(C 6 Et 6 )⋅⋅⋅F − ( 80 ; Figure ), the calculated binding energy was 146 kcal mol −1 . The well‐established propensity of HEB to form adducts with threefold symmetry is also found for 1,3,5‐triethylbenzene and its derivatives.…”