A new post-synthetic polymerization strategy makes metal-organic frameworks more stable

Area of Science:

• Materials Science
• Chemistry

Background:

• Metal-organic frameworks (MOFs) show promise for host-guest applications.
• MOFs often lack stability in aqueous solutions, especially at extreme pH levels, hindering their practical use.

Purpose of the Study:

• To develop a facile post-synthetic method for enhancing the stability of diverse MOFs in aqueous environments.
• To create hydrophobic MOF composites with improved durability for host-guest applications.

Main Methods:

• A two-step, post-synthetic polymerization technique involving polydopamine coating.
• Grafting hydrophobic molecules onto the MOF surface via Michael addition after polydopamine coating.
• Testing the stability of modified MOFs (HKUST-1, ZIF-67, ZIF-8, UiO-66, Cu-TDPAT, Mg-MOF-74, MIL-100) in acidic and basic conditions using powder X-ray diffraction and surface area analysis.

Main Results:

• The post-synthetic modification significantly enhanced the hydrophobicity and stability of various MOFs.
• Modified MOFs retained their structural integrity and surface area in harsh wet, acidic, and basic conditions.
• The method proved effective across a structurally diverse range of MOFs.

Conclusions:

• This simple, mild post-synthetic polymerization method offers a viable strategy to improve MOF stability in aqueous environments.
• The developed hydrophobic MOF composites are suitable for host-guest applications requiring durability in challenging conditions.