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 ‐ and trans , cis ‐bis‐formamide 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.