Precedent and Theory Unite in the Hypothesis of a Highly Selective Fluoride Receptor

Abstract

Platz für was Kleines: Für mehrere [1,3,5]Cyclophan‐basierte Rezeptoren, die Triazin‐, Cyanursäure‐ oder Boroxinringe enthalten, wird vorhergesagt, dass sie Fluoridionen mit einer Kombination aus Anion‐π‐Wechselwirkungen und Ionenpaar‐verstärkten H‐Brückenbindungen fest komplexieren und zugleich das Chloridion wegen seiner Größe ausschließen. Die berechnete Struktur des Triazinkäfigs mit eingeschlossenem Fluoridion ist gezeigt.

Fluoride‐Selective Host Based on Anion–π Interactions, Ion Pairing, and Hydrogen Bonding: Synthesis and Fluoride‐Ion Sandwich Complex

“…In the theoretical treatment of this receptor, the complexation of fluoride ion was shown to benefit from intrinsically stronger π⋅⋅⋅X − ⋅⋅⋅π and + NH⋅⋅⋅X − interactions than for chloride. This difference, in addition to acute steric issues associated with accommodating the larger chloride anion in the cavity, led to a calculated 23.5 kcal mol −1 difference in binding energy between the two halides in aqueous solution 9. Herein, we present the proof of principle behind the design of 2 .…”

“…We ourselves described a hypothetical series of purpose‐designed fluoride receptors that took advantage of the cylindrophane effect, that is, the high conformational stability and limited vertical flexibility of [1,3,5]cyclophanes bridged by chains with odd numbers of atoms, such as 1 (Scheme ). While 1 has been shown to be a selective silver(I) and copper(I) host,8 it was demonstrated that an inversion of its electronic character from electron‐rich to electron‐poor, such as in 2 , would produce an anion host 9. In the theoretical treatment of this receptor, the complexation of fluoride ion was shown to benefit from intrinsically stronger π⋅⋅⋅X − ⋅⋅⋅π and + NH⋅⋅⋅X − interactions than for chloride.…”

Substituent Effects on Non‐Covalent Interactions with Aromatic Rings: Insights from Computational Chemistry

“…They found that fluoride forms a covalent bond with an aryl carbon, while chloride and azide exhibit a non-covalent minimum with the anion located above the ring. In later work, Mascal [84] used B3LYP to investigate complexes of s-triazine, cyanuric acid, and boroxine ring with fluoride and chloride, finding that the complexes with fluoride are more favorable than the corresponding Cl À complexes.…”

Comparison of σ‐Hole and π‐Hole Tetrel Bonds Formed by Pyrazine and 1,4‐Dicyanobenzene: The Interplay between Anion–π and Tetrel Bonds

“…Numerous experimental and theoretical research findings have demonstrated that the anion-p interaction is of importance in molecular recognition and transmembrane anion transport. [8][9][10][11][12][13][14][15] It hasb een revealed that the anion-p interaction is mainly caused by electrostatic and anion-induced polarization interactions. [16][17][18] Recently,m uch attention has been focusedo nt etrel bonding (TB) due to its roles in chemical reactions, crystal engineering, and biological systems.…”