EPR-refined atomistic molecular dynamics delivers predictive spectroscopy in self-organised soft matter systems [dataset]

Electron paramagnetic resonance (EPR) spectroscopy with nitroxide spin probes is a sensitive probe of structural dynamics in soft matter. Here we report the use EPR to test and refine atomistic molecular dynamics (MD) force fields for the discotic liquid crystal 2,3,6,7,10,11 hexa(hexyloxy)triphenylene (HAT6). We show that subtle variations in partial charge schemes, aromatic core Lennard Jones interactions, and alkoxy torsional potentials cause pronounced changes in predicted EPR line shapes. By comparing experimental and MD-predicted spectra at a reference temperature, we identify refined parameters that reproduce both the measured spectra and the isotropic–columnar phase transition temperature. The predictions reveal pretransitional growth of short molecular stacks in the isotropic phase and the emergence of columnar order on cooling. This work establishes EPR spectroscopy as a powerful benchmark for testing and improving molecular force fields and delivers the first fully atomistic prediction of variable temperature EPR spectra of a discotic liquid crystal.