Hydrogen-Bond-Driven Peptide Nanotube Formation: A DFT Study.

Area of Science:

• Supramolecular Chemistry
• Computational Chemistry
• Materials Science

Background:

• Self-assembly of peptide-based nanomaterials is crucial for advanced applications.
• Understanding the driving forces behind nanotube formation is key to controlling their structure and properties.

Purpose of the Study:

• To investigate the role of hydrogen bonding in the self-assembly of peptide nanotubes.
• To determine the contribution of various hydrogen bond types, including weak C-H· · ·O bonds, to nanotube stability.
• To analyze the influence of molecular structure, specifically hydrocarbon chain length, on nanotube formation and energetics.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to model the system.
• The wB97XD/DGDZVP method was used for accurate energy calculations.
• Geometries and binding energies of H-bond-driven peptide nanotubes were examined.

Main Results:

• Nanotube formation is driven by both direct hydrogen bonds (carboxy/amide groups) and weaker C-H· · ·O hydrogen bonds.
• Intratubular O-H· · ·O=C hydrogen bonds contribute approximately one-third of the total binding energy.
• Hydrocarbon chains play a stabilizing role, and nanotube diameter increases with monomer number.
• Lengthening occurs via intertubular O-H· · ·O=C hydrogen bonds, with average binding energy stabilizing around 15 kcal/mol.

Conclusions:

• Hydrogen bonds, including weak C-H· · ·O interactions, are critical for peptide nanotube self-assembly.
• The molecular design, particularly the hydrocarbon linker, significantly impacts nanotube stability and structure.
• DFT calculations provide valuable insights into the energetics and mechanisms governing peptide nanotube formation.