Chalcogen Bonds: How to Characterize Them in Solution?

Abstract

Chalcogen bond (ChB) occurs between molecules containing Lewis acidic chalogen substituents and Lewis bases. Recently, ChB emerged as a pivotal interaction in solution-based applications such as anion recognition, anion transport and catalysis. However, before moving to applications, the involvement of ChB must be established in solution. In this Concept article, we provide a brief review of the currently available experimental investigations of ChB in solution.

Halide Complexes of 5,6‐Dicyano‐2,1,3‐Benzoselenadiazole with 1 : 4 Stoichiometry: Cooperativity between Chalcogen and Hydrogen Bonding

“…Therefore, taking into account previous results [72–86] and very tentatively, the 1 +[Hal] − ↔[ 1 −Hal] − equilibrium (Scheme 2) can be assumed for the reaction mixtures, with the formation/synthesis of [ 1 4 −Hal] − occurring during crystallization of the isolated products employing HB . In this particular study, the conventional solution NMR and ESI‐MS, which typically are reliable and informative, [40,72–74,76,78,104] yielded limited results. With variable‐temperature 35 Cl and ambient‐temperature 77 Se NMR, only the fact of interaction between 1 and [Hal] − in solution was confirmed; whereas with ESI‐MS, no anionic complexes were detected (SI).…”

“…Amongst SBIs used for anions recognition and sensing, hydrogen, [21–23] halogen [24–31] and chalcogen [26,29–48] bondings ( HB , XB and ChB , respectively), are, perhaps, the most important; [29,42] in the case of chalcogens, they embrace also hypervalent derivatives, e. g. EF 5 (E=S, Se, Te) [49] . Combination of anion‐ and cation‐receipting moieties in a single scaffold is possible to provide cooperative ion‐pair recognition [30,50] …”

“…[4,[7][8][9][10][11][12][17][18][19]20] Amongst anions, halides [Hal] À (Hal = F, Cl, Br, I) are essentially important for living beings and their environment. [19] Amongst SBIs used for anions recognition and sensing, hydrogen, [21][22][23] halogen [24][25][26][27][28][29][30][31] and chalcogen [26,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] bondings (HB, XB and ChB, respectively), are, perhaps, the most important; [29,42] in the case of chalcogens, they embrace also hypervalent derivatives, e. g. EF 5 (E = S, Se, Te). [49] Combination of anion-and cation-receipting moieties in a single scaffold is possible to provide cooperative ion-pair recognition.…”

Competition between Binding to Various Sites of Substituted Imidazoliums

“…It has been understood for some time that the formation of an HB induces changes in the chemical shielding of not only the bridging proton but also neighboring atoms such as the atom bonded to H and the electron-donating base atom. More recent work has documented evidence that the formation of other noncovalent bonds that are closely related to HBs, such as halogen and chalcogen bonds, also induces clear shifts in the NMR signal of the atoms involved. − Of this set of atoms, the one that appears to bear the closest correlation with the strength of the bond is the electron donor atom, ,, which in this case would be the N of NH 3 .…”

Chalcogen Bonding Catalysis: Tellurium, the Last Frontier?

“…In the initial works, trials and errors were the usual way, but now, several studies have been performed to better understand the ChB behaviour and strength in solution (Figure 4). [31] Data regarding the thermodynamics of the ChB in solution and the solvent influence are sparse. In 2010, Gabbaï et al designed a bidendate Lewis acid containing a telluronium cation as a recognition site for fluoride (Figure 4A).…”