Exploring Multifunctional Hydrogen-Bonded Organic Framework Materials

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Nanotechnology

Background:

• Hydrogen-bonded organic frameworks (HOFs) are emerging multifunctional materials assembled from organic molecules via hydrogen bonding and π–π interactions.
• Compared to zeolites, MOFs, and COFs, HOFs are less stable due to weaker hydrogen bonds but offer easier recovery and regeneration.
• HOFs exhibit flexibility, allowing tunable porosity for various applications, and are compatible with biomolecules for potential biomedical uses.

Purpose of the Study:

• To explore the development and diverse applications of porous Hydrogen-bonded organic frameworks (HOFs).
• To showcase the construction of HOFs using various organic functional groups and their systematic pore tuning.
• To highlight HOFs' potential in gas separations, enantioselective separations, sensing, and optical applications.

Main Methods:

• Self-assembly of organic molecules with functional sites like carboxylic acid, amine, aldehyde, and cyano groups to form HOFs.
• Systematic tuning of pore sizes and introduction of specific binding sites within the HOF framework.
• Utilizing framework flexibility and directional hydrogen bonding for controlled porosity and material properties.

Main Results:

• Successfully constructed porous HOFs using diverse organic building blocks, including 2,4-diaminotriazine (DAT), carboxylic acid (COOH), aldehyde (CHO), and cyano (CN).
• Achieved selective gas separations for various industrially relevant gas pairs (e.g., C2H2/C2H4, CO2/N2, Xe/Kr) and enantioselective separation of alcohols.
• Developed HOF materials for luminescent sensing and optical lasing applications using optically active organic molecules.

Conclusions:

• HOFs represent a promising class of porous materials with tunable properties and diverse applications.
• The weak and reversible nature of hydrogen bonds in HOFs allows for facile processing, regeneration, and flexible framework design.
• Ongoing research in HOFs is expected to yield novel materials with unprecedented functionalities beyond current imagination.