Precise heteroatom doping determines aqueous solubility and self-assembly behaviors for polycyclic aromatic skeletons

Area of Science:

• Materials Science
• Organic Chemistry
• Physical Chemistry

Background:

• Improving the hydrophilicity and aqueous solubility of hydrophobic molecules is crucial for diverse applications.
• Hydrophobic molecular scaffolds limit their utility in aqueous environments, necessitating solubility enhancement strategies.

Purpose of the Study:

• To investigate the effect of stepwise and precise N/O heteroatom doping on the hydrophilicity and aqueous solubility of polycyclic aromatic skeletons.
• To explore the relationship between heteroatom doping and molecular solubility using Hansen solubility parameters (HSP).
• To examine the self-assembly behavior and properties of water-soluble doped molecules.

Main Methods:

• Stepwise and precise doping of polycyclic aromatic skeletons with nitrogen (N) and oxygen (O) heteroatoms.
• Hansen solubility parameters (HSP) analysis to quantify solubility and interactions.
• Nuclear Magnetic Resonance (NMR) spectroscopy and single crystal X-ray analysis to characterize molecular structure and interactions.
• Investigation of self-assembly into nanoparticles and their properties (luminescence, quasi-solid behavior).

Main Results:

• Gradual alteration of molecular structures from hydrophobic to hydrophilic through N/O heteroatom doping.
• Hansen solubility parameters (HSP) correlated with doping species, number, and position, indicating enhanced hydrogen bonding interactions with water.
• Three optimized molecules exhibited excellent aqueous solubility and self-assembled into stable nanoparticles in water.
• NMR and luminescence studies revealed quasi-solid properties of the self-assembled ensembles in aqueous media.

Conclusions:

• Stepwise and precise N/O heteroatom doping is an effective strategy to achieve tunable hydrophilicity and excellent aqueous solubility in hydrophobic molecular scaffolds.
• Hansen solubility parameters (HSP) provide valuable insights into the role of hydrogen bonding in enhancing solubility.
• The resulting water-soluble molecules can form stable nanoparticles with unique quasi-solid properties, opening avenues for advanced material applications.