Dataset from DFT Calculations and RDG Analysis for Interactions in a Chitosan/Cassava Starch/Anthocyanin Composite Film

1 Research Hypothesis:
This research hypothesizes that at the pH condition (4.4) of the film-forming solution, chitosan (CH), cassava starch (CS), and purple sweet potato anthocyanin (PSPA) can form stable complexes through non-covalent interactions. These molecular-level interactions, primarily hydrogen bonds and van der Waals forces, are responsible for the enhanced mechanical properties and structural compactness observed in the composite film, and underpin its function as a pH-responsive indicator for pork freshness.
2 What the Data Shows:
Individual Component Calculations:
Chitosan.gjf, Chitosan.chk, Chitosan-ESP.txt: DFT input, output, and electrostatic potential data for chitosan tetramer
cassava_starch.gjf, cassava_starch.chk, cassava_starch-ESP.txt: DFT input, output, and ESP data for starch tetramer
carbinol_pseudobase.gjf, carbinol_pseudobase.chk, carbinol_pseudobase-ESP.txt: DFT input, output, and ESP data for anthocyanin derivative
Complex Calculations:
Chitosan-carbinol_pseudobase.gjf, Chitosan-carbinol_pseudobase.chk: DFT input and output for chitosan-anthocyanin complex
cassava_starch-carbinol_pseudobase.gjf, cassava_starch-carbinol_pseudobase.chk: DFT input and output for starch-anthocyanin complex
Chitosan-carbinol_pseudobase-RDG-output.txt, cassava_starch-carbinol_pseudobase-RDG-output.txt: Non-covalent interaction analysis results
3 Notable Findings and Interpretation:
The ESP analysis revealed that protonated chitosan has a strong positive potential around its -NH₃⁺ groups, making it an excellent hydrogen bond donor. PSPA and starch showed significant negative potential around their oxygen atoms, acting as hydrogen bond acceptors.
Molecular docking corroborated this, identifying five hydrogen bonds in the CH-PSPA complex and two in the CS-PSPA complex. The short bond distances (< 2.9 Å) indicate stable and favorable interactions.
The NCI analysis provided direct evidence of these non-covalent interactions, with clear blue isosurfaces (signifying strong hydrogen bonds) and green regions (signifying van der Waals interactions) between the molecules. This computational evidence strongly supports the experimental FTIR and XRD findings that hydrogen bonding is a key mechanism within the film matrix.