Studies on supramolecular gel formation using DOSY NMR.

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Analytical Chemistry

Background:

• Low-molecular-weight gelators (LMWGs) form supramolecular gels through self-assembly.
• Understanding molecular mobility and self-assembly is crucial for gel properties.

Purpose of the Study:

• To investigate the supramolecular self-assembly and molecular mobility of LMWGs in organic solvents.
• To determine the critical gelation concentration (CGC) and gel-to-sol transition temperatures.
• To elucidate the stepwise self-assembly process leading to gelation.

Main Methods:

• Pulsed field gradient (PFG) diffusion ordered spectroscopy (DOSY) Nuclear Magnetic Resonance (NMR) was employed.
• Concentration-dependent and variable-temperature DOSY NMR experiments were conducted.
• Data analysis included monoexponential processing and Bayesian transformation for 2D DOSY plots.

Main Results:

• DOSY NMR successfully monitored the self-assembly of LMWGs.
• Critical gelation concentrations (CGC) were determined for selected LMWGs.
• Gel-to-sol transition temperatures were identified using variable-temperature experiments.

Conclusions:

• PFG DOSY NMR is a powerful tool for studying LMWG self-assembly and gelation.
• The method provides insights into the stepwise assembly of molecules into supramolecular gels.
• This approach is applicable for characterizing CGC and gel melting points of supramolecular gels.