Exploiting the Strong Hydrogen Bond Donor Properties of a Borinic Acid Functionality for Fluoride Anion Recognition.

Borinic acids have typically not been considered as hydrogen bond donor groups in molecular recognition. Described herein is a bifunctional borane/borinic acid derivative ( 2) in which the two functionalities are connected by a 1,8-biphenylenediyl backbone. Anion binding studies reveal that 2 readily binds a fluoride anion by formation of a unique B−F⋅⋅⋅H−O−B hydrogen bond. This hydrogen bond is characterized by a short H-F distance of 1.79(3) Å and a large coupling constant (1 JHF) of 57.2 Hz. The magnitude of this interaction, which has also been investigated computationally, augments the fluoride anion binding properties of 2, thus making it compatible with aqueous environments. [ABSTRACT FROM AUTHOR]