Synthesis, Structure, and Thermal Stability of a Mesoporous Titanium(III) Amine-Containing MOF

Area of Science:

• Materials Science
• Inorganic Chemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) offer tunable porosity and high surface areas for diverse applications.
• Previous research focused on monometallic MOFs, limiting exploration of synergistic effects in bimetallic systems.
• Amine functionalization in MOFs can enhance interactions with specific guest molecules.

Purpose of the Study:

• To synthesize and characterize the first mesoporous bimetallic Ti/Al MOF with amine functionalities.
• To investigate the structural stability and hydrogen sorption properties of the novel material.
• To compare its performance with existing monometallic titanium MOFs.

Main Methods:

• Solvothermal synthesis using a Ti-Al precursor and 2-aminoterephthalic acid.
• Thermal gravimetric analysis (TGA) and in situ powder X-ray diffraction (PXRD) for stability assessment.
• Nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, and inductively coupled plasma (ICP) for structural and compositional analysis.
• Gas sorption experiments to evaluate hydrogen affinity.

Main Results:

• Successful synthesis of a Ti/Al MOF, NH ₂-MIL-101(Ti^III), structurally related to NH ₂-MIL-101(M).
• The MOF demonstrated structural stability up to 200 °C and contains trinuclear Ti ₃ clusters.
• NH ₂-MIL-101(Ti^III) exhibited a higher affinity for hydrogen compared to monometallic Ti^III MOFs.

Conclusions:

• A novel, air-sensitive, mesoporous bimetallic Ti/Al MOF with amine linkers was successfully synthesized.
• The material shows promising structural stability and enhanced hydrogen sorption properties.
• This work opens avenues for developing advanced bimetallic MOFs for gas storage applications.