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Spin diffusion transfer difference (SDTD) NMR: An advanced method for the characterisation of water structuration
Valeria Gabrielli1, Agne Kuraite1, Marcelo Alves da Silva2
1School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
Journal of Colloid and Interface Science
|March 23, 2021
Summary
A new Spin Diffusion Transfer Difference (SDTD) NMR method quantifies solvent structuration in colloidal systems. This technique overcomes limitations of classical STD NMR, offering insights into particle/solvent interfaces.
Area of Science:
- Supramolecular chemistry
- Colloid and interface science
- Nuclear Magnetic Resonance (NMR) spectroscopy
Background:
- Classical Saturation Transfer Difference (STD) NMR for monitoring solvent interactions in gels is limited by gelator and solvent concentrations.
- It does not accurately report on the degree of solvent structuration at the particle/solvent interface.
- Characterizing solvent structuration is crucial for understanding the behavior of colloidal systems.
Purpose of the Study:
- To develop a novel NMR protocol for characterizing solvent structuration at the particle/solvent interface in colloidal systems.
- To overcome the concentration dependencies of classical STD NMR.
- To investigate solvent organization in dispersions of large gelator particles.
Main Methods:
- A systematic study was conducted on the effects of gelator and solvent concentrations, and gelator surface charge, on STD NMR build-up curves.
- Solvent interactions were characterized in dispersions of starch and cellulose-like particles using deuterated water and alcohol/D2O mixtures.
- A new Spin Diffusion Transfer Difference (SDTD) NMR protocol was developed, incorporating 1H-1H spin diffusion transfer and a 1D diffusion equation.
Main Results:
- The developed SDTD NMR protocol is independent of gelator and solvent concentrations, enabling accurate estimation of solvent structuration.
- This method allows for the determination of minimum distances (r) and spin diffusion rates (D) at the particle/solvent interface through simulation of SDTD build-up curves.
- The protocol successfully characterized solvent interactions in starch and cellulose-like particle dispersions.
Conclusions:
- The SDTD NMR protocol provides a robust method for quantifying solvent structuration in colloidal systems.
- This technique offers a significant advancement over classical STD NMR for studying particle/solvent interfaces.
- The protocol is readily extendable to diverse colloidal systems composed of large particles.
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