Effects of solvent on weak halogen bonds: Density functional theory calculations

Abstract

In recent years, many applications of solution-phase halogen bonding in anion recognition, catalysis, and pseudorotaxane formation have been reported. Moreover, a number of thermodynamic data of halogen bonding interactions in organic solution are now available. To obtain detailed information of the influence of the surrounding medium on weak halogen bonds, a series of dimeric complexes of halobenzene (PhX) with three electron donors (H 2 O, HCHO, and NH 3 ) were investigated by means of DFT/PBE calculations in this work. The PCM implicit solvation approach was utilized to include the effects of three solvents (cyclohexane, chloroform, and water) as representatives for a wide range of dielectric constant. In some cases, halogen-bond distances are shown to shorten in solution, accompanied by concomitant elongation of the CAX bonds. For the remaining systems, the intermolecular distances tend to increase or remain almost unchanged under solvent effects. In general, the solvent has a slight destabilizing effect on weak halogen bonds; the strength order of halogen bonds observed in vacuum remains unchanged in liquid phases. Particularly, the interaction strength attenuates in the order I > Br > Cl in solution, consistent with the experimental measurements of weak halogen bond door abilities. The similarities between halogen and hydrogen bonding in solution were also elucidated. The results presented herein would be very useful in future applications of Correspondence

Solvent effect on halogen bonding: The case of the I⋯O interaction

“…From the geometrical point of view, on the other hand, the presence of the solvent implies a systematic decrease in the I· · ·O distances at all theoretical levels, as previously reported for other halogen bonded dimers [18]. Moreover, we observe an increase (towards 180 • ) of the C I· · ·O angles on going from vacuo to diethylether and then to water, leading to halogen bonds very close to the linear arrangement.…”

“…Up to now, however, there are only few theoretical investigations of the solvent effect on the halogen bond properties [16][17][18].…”

“…Calculations have been performed on dimers constituted by iodobenzene derivatives with formaldehyde in two solvents (diethylether and water). In the present study, the results of previous investigations on halogen bonding in solution [16][17][18] are complemented by taking into consideration different substitution schemes on the iodobenzene ring, in order to systematically modulate the force of the halogen bond, from weak to moderate interaction. The choice of formaldehyde is due to the fact that a survey [23] of protein-halogenated ligand complexes has evidenced the frequent occurrence of halogen bonding with oxygen atoms of a peptidic bond.…”

Quantum chemical studies of non-covalent interactions between the ethyl cation and rare gases

“…As can be seen, the DZPE corrections outweigh BSSE, although in some cases, the BSSE values are negative [83], even though the interaction energy of -7.69 kJÁmol À1 reveals that III is the most stable complex. Contrary to what one might point out, intermolecular interactions with low energies are not unusual, as confirmed by a work by Lu et al [84]. Of course, small BSSE amounts were also obtained, and above all else, this was also verified in weakly bound complexes modeled through the B3LYP/6-311 + +G(d,p) theoretical level [85].…”

Rotaxanes and pseudorotaxanes with threads containing viologen units

“…Rotaxanes 1-5 and pseudorotaxanes [6][7][8][9] are examples of mechanically interlocked species, 10,11 besides them, to interlocked architectures belong also catenanes, [12][13][14][15] as well as more complex structures such as trefoil knots, 16 Solomon knots, 17 Borromean rings, 18 daisy chains 19 or ravels.…”