High-Fidelity Multistate Switching with Anion-Anion and Acid-Anion Dimers of Organophosphates in Cyanostar Complexes.

The acid-base switching of complexes formed from anti-electrostatic anion-anion homodimers of organophosphates and cyanostar macrocycles was investigated for the first time. High-fidelity 2:2 complexes were selected by using suitably sized organo substituents. Reversible and direct switching occurs with triflic acid and hydroxide base. An unexpected acid⋅⋅⋅anion heterodimer was discovered with weaker picric acid, which helped reveal some of the elementary steps. Switching can also proceed in a cooperative (strong anion then weak acid) or stepwise manner (weak acid then strong anion).