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Analysing π-π-stacking interactions in lignin nanoparticles from molecular simulations - insights and lessons learned
Klara Hackenstrass1, Nil Tabudlong Jonasson1, Marie Hartwig-Nair1
1Division of Applied Mechanics, Department of Materials Science and Engineering, Uppsala University, Uppsala, Sweden. malin.wohlert@angstrom.uu.se.
Faraday Discussions
|September 22, 2025
Summary
Researchers developed a method to identify pi-pi stacking in molecular dynamics. Analysis revealed that WAXS peaks previously attributed to stacking in lignin models were actually due to other structural features.
Area of Science:
- Computational chemistry
- Materials science
- Biochemistry
Background:
- Pi-pi stacking is a key interaction in aromatic compounds, influencing material properties.
- Understanding these interactions is crucial for designing advanced materials, particularly from biomass sources like lignin.
Purpose of the Study:
- To develop and validate a computational method for recognizing pi-pi stacking in molecular dynamics simulations.
- To investigate the structural origins of peaks observed in wide-angle X-ray scattering (WAXS) profiles of lignin models.
Main Methods:
- Developed a geometric criteria-based method to identify pi-pi stacking from molecular dynamics trajectories.
- Applied the method to lignin dimer, tetramer, and octamer systems.
- Calculated wide-angle X-ray scattering profiles from molecular dynamics data for comparison with experimental results.
Main Results:
- The developed method successfully identified pi-pi stacking interactions based on distance, angular, and displacement criteria.
- Calculated WAXS profiles for a lignin tetramer model showed agreement with experimental data.
- In-depth analysis indicated that a WAXS peak attributed to sandwich-like stacking was primarily caused by other intramolecular structural motifs, not pi-pi stacking.
Conclusions:
- The computational method provides a reliable way to detect pi-pi stacking in molecular simulations.
- Re-evaluation of WAXS data is necessary, as observed peaks in lignin materials may not solely represent pi-pi stacking.
- Combining X-ray scattering with molecular modeling offers powerful insights into complex material structures.
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