Shape-independent model (SHIM) approach for studying aggregation by NMR diffusometry

Santiago, Adrian A. Hernandez and Buchelnikov, Anatoly S. and Rubinson, Maria A. and Yesylevskyy, Semen O. and Parkinson, John A. and Evstigneev, Maxim P. (2015) Shape-independent model (SHIM) approach for studying aggregation by NMR diffusometry. Journal of Chemical Physics, 142 (10). 104202. ISSN 0021-9606

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    NMR diffusometry has been gaining wide popularity in various areas of applied chemistry for investigating diffusion and complexation processes in solid and aqueous phases. To date, the application of this method to study aggregation phenomena proceeding beyond the dimer stage of assembly has been restricted by the need for a priori knowledge of the aggregates’ shape, commonly difficult to know in practice. We describe here a comprehensive analysis of aggregation parameter-dependency on the type and shape selected for modeling assembly processes, and report for the first time a shape-independent model (designated the SHIM-model), which may be used as an alternative in cases when information on aggregates’ shapes are unavailable. The model can be used for determining equilibrium aggregation parameters from self-diffusion NMR data including equilibrium self-association constant and changes in enthalpy, ΔH, and entropy, ΔS.