Energetic Metal-Organic Frameworks Incorporating NH₃OH⁺ for New High-Energy-Density Materials

Area of Science:

• Materials Science
• Chemistry
• Energetic Materials

Background:

• Energetic metal-organic frameworks (E-MOFs) are a developing class of materials.
• The energetic cation hydroxylammonium (NH3OH+) has not been previously incorporated into transition-metal-based E-MOFs.

Purpose of the Study:

• To synthesize and characterize the first NH3OH+-containing E-MOFs.
• To evaluate the thermal stability, energy density, and sensitivity of these novel materials.

Main Methods:

• Synthesis of copper and manganese-based E-MOFs using bis(tetrazole)methane (H2btm) ligand.
• Crystal structure determination.
• Experimental evaluation of thermal decomposition temperature, heat of combustion, heat of detonation, and impact/friction sensitivity.

Main Results:

• Two novel 2D layered E-MOFs, [(NH3OH)2(Cu(btm)2)] and [(NH3OH)2(Mn(btm)2)], were successfully synthesized.
• Both compounds exhibit high thermal decomposition temperatures (>200 °C), with the Cu-based E-MOF showing exceptional stability (230.3 °C).
• The Cu-based E-MOF demonstrates superior energy density (heat of combustion: 11447 kJ kg-1; heat of detonation: 713.8 kJ mol-1) and distinct sensitivity properties compared to the Mn-based counterpart, which is classified as an insensitive high-energy-density material.

Conclusions:

• This research presents the first examples of NH3OH+-containing transition-metal E-MOFs.
• These novel materials offer a unique combination of high energy density, tunable thermal stability, and controllable sensitivity.
• The findings open new avenues for designing advanced energetic materials with tailored properties for diverse applications.