An operationally-simple deuterium isotopic perturbation method has been developed as an extension of SIMPLE (secondary isotope multiplets of partially labeled entities) NMR to characterize intramolecular OH/OH hydrogen bonds. This method has been developed through measuring equilibrium isotope effects (EIEs) in a variety of different molecules that possess weak as well as strong intramolecular H-bonds. Through measuring the response to varying amounts of H-bond additives (such as CD3OD), we have identified intriguing relationships between the measured EIE and the relative strength of the intramolecular H-bond. Furthermore, a series of computational investigations (MM and QM) have been conducted that further elucidate the relative strength of intramolecular H-bonds. These computational calculations have also identified key stoichiometric amounts of H-bond additives needed to disrupt weak and strong intramolecular OH/OH bonds. Overall, the computational EIE predictions corroborate experimental observations and further support the NMR titration method. In summary, through a parallel experimental and computational investigation, the newly-developed method is a versatile technique for the probing the strength of strong as well as weak intramolecular OH/OH bonds.

Measuring the relative strength of intramolecular OH/OH bonds through equilibrium isotope effects (EIEs)

255th National Meeting (2018)

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