Kinetic Stabilities and Exchange Dynamics of Water‐Soluble Bis‐Formamide Caviplexes Studied Using Diffusion‐Ordered NMR Spectroscopy (DOSY)

A deep cavitand binds long-chain trans , trans isomers in water solution giving a pair of caviplexes in a ca. 60:40 ratio. Both caviplexes display in/out guest exchange dynamics that are slow on the 1 H NMR chemical shift timescale, but fast on the EXSY timescale. We apply diffusion-ordered NMR spectroscopy (DOSY) to characterize the caviplexes. On the diffusion timescale, the guest in/out exchange processes feature intermediate dynamics allowing the assessment of their kinetic stabilities. We found that the trans , cis -bis-formamide isomers form kinetically more stable caviplexes than the trans , trans -counterparts. We also show that the kinetic stabilities of the bis-formamide caviplexes relate well with their relative thermodynamic stabilities. Fortunately, the tuning of the DOSY parameters allowed the observation of the exchange dynamics as slow processes on the experiment timescale.