Chain length dependent alkane/β-cyclodextrin nonamphiphilic supramolecular building blocks

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Physical Chemistry

Background:

• Nonamphiphilic supramolecular building blocks are crucial for self-assembly.
• Host-guest inclusion complexes, such as alkanes and beta-cyclodextrins (β-CD), offer unique properties.
• Understanding the influence of guest molecule chain length on host-guest complex behavior is essential for designing novel materials.

Purpose of the Study:

• To investigate the chain length dependent behavior of nonamphiphilic supramolecular building blocks.
• To elucidate the structural transitions of alkane@β-CD complexes.
• To identify the driving forces and mechanisms behind vesicle formation.

Main Methods:

• Proton Nuclear Magnetic Resonance ((1)H NMR) spectroscopy.
• Electrospray Ionization Mass Spectrometry (ESI-MS).
• Small-Angle X-ray Scattering (SAXS).
• Fourier-Transform Infrared (FT-IR) spectroscopy.
• Thermogravimetric Analysis (TGA).

Main Results:

• The structure of alkane@β-CD building blocks transitions from channel type 2alkane@2β-CD to channel type alkane@2β-CD, and finally to non-channel type 2alkane@2β-CD as alkane chain length increases.
• Hydrogen bonding was identified as a primary driving force for vesicle formation.
• Water molecules are integral to vesicle formation, acting as structural water, with an average of 16-21 water molecules associated per building block.

Conclusions:

• Alkane chain length dictates the supramolecular structure of alkane@β-CD complexes.
• Vesicle formation is driven by hydrogen bonding and stabilized by structural water.
• The findings offer a fundamental understanding of self-assembly in nonamphiphilic systems.