Halogen bonding: a general route in anion recognition and coordination

Abstract

This critical review describes how halocarbons can function as effective binding sites of anions via halogen bonding, the noncovalent interaction whereby halogen atoms accept electron density. The focus is on the binding and coordination of oxyanions, by far the most numerous class of anions in organic chemistry. It is shown how a large variety of inorganic and organic oxyanions can form discrete adducts and 1D, 2D, or 3D supramolecular networks with chloro-, bromo-, and iodocarbons. Specific examples are discussed in order to identify new supramolecular synthons based on halogen bonding and to outline some general principles for the design of effective and selective receptors based on this interaction. The interaction allows for several other anions to self-assemble with halocarbons and mention is also given to the halogen bonding-based coordination of halides, polycyano- and polyoxometallates (72 references).

Superfluorinated Ionic Liquid Crystals Based on Supramolecular, Halogen‐Bonded Anions

“…Incorporation of Eu‐containing counteranions can give mesophases that show the luminescence of the anion,26 whereas iodide appears promising when using the ILC as a hole‐transporting layer in dye‐sensitized solar cells 12, 13, 14. Halide‐containing anions are encountered rather frequently in ionic liquids and importantly, they can also serve as electron‐donating moieties in halogen bonding 27, 28, 29…”

“…The electron‐donating halogen bond acceptors can be neutral Lewis bases such as pyridine groups,44 or charged species such as mono‐ to tetradentate iodide anions 27. In the latter case, the number of halogen bonds in which the anion is involved depends on both the shape and the valence of the partner 28. Taking into account: 1) the potential of halogen bonding in constructing supramolecular liquid crystals, and 2) the ability of the commonly used halide counteranions of ionic liquids to act as halogen‐bond acceptors, it seems feasible to utilize halogen bonding in designing novel types of ILCs with potentially unprecedented properties and tunability.…”

Natural Abundance 15N and 13C Solid‐State NMR Chemical Shifts: High Sensitivity Probes of the Halogen Bond Geometry

“…10-14 XB plays also a key role in anion recognition and coordination both in solid state and in solution, 15,16 ability of relevant interest especially for biological systems. 17 The 2013 IUPAC XB definition states: "A halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity".…”

Communication: Competition between π⋯π interaction and halogen bond in solution: A combined 13C NMR and density functional theory study

“…The hydrogen bond is probably the most important noncovalent bond. 1,2 Other important noncovalent driving forces for supramolecular assembly include π · · ·π stacking interaction, [3][4][5][6][7][8][9][10][11][12][13] halogen bond, [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] etc. Noncovalent bonds are much weaker than the covalent bonds.…”