Electrochemical Activation of TTF-Based Halogen Bond Donors: A Powerful, Selective and Sensitive Analytical Tool for Probing a Weak Interaction in Complex Media

Herein we demonstrate the electrochemical activation and detection of intermolecular halogen bonding (XB) in solution by generating the cation radical of iodo-trimethyltetrathiafulvalene (I-Me3TTF center dot(+)) in the presence of various Lewis-basic anions. This work is leading to the endorsement and generalization of the concept of electrostimulating XB for molecular recognition by adjusting the properties of the XB donor via the electrochemical reversible generation of charged species. The formation of the interaction between I-Me3TTF center dot+ and Lewis bases has been investigated by cyclic voltammetry allowing to quantify the strength of the interaction (K-ox = 100 to 400 M-1 and Delta G = -12 to -15 kJ mol(-1)). Moreover spectroelectrochemical measurements along with TD-DFT calculations have confirmed XB formation upon generation of the radical cation. The present work opens broad perspectives for the development of redox switchable XB donors in the field of molecular recognition in chemical and biological systems where non-covalent interactions are usually key governing parameters.