High Proton Conduction in Two Highly Water-Stable Lanthanide Coordination Polymers from a Triazole Multicarboxylate...

Area of Science:

• Materials Science
• Inorganic Chemistry
• Solid-State Chemistry

Background:

• Lanthanide coordination polymers (CPs) are explored for their unique properties.
• Proton conductivity in solid-state materials is crucial for energy applications.
• Developing efficient proton conductors remains a significant challenge.

Purpose of the Study:

• To synthesize and characterize novel lanthanide coordination polymers (CPs).
• To investigate the proton conductivity of these CPs.
• To elucidate the mechanisms governing proton transport.

Main Methods:

• Solvothermal synthesis of lanthanide CPs.
• Single-crystal X-ray diffraction for structural analysis.
• Alternating current (AC) impedance spectroscopy for conductivity measurements.
• Water vapor adsorption studies.

Main Results:

• Two isostructural lanthanide CPs, [Er(Hmtbd)(H2mtbd)(H2O)3]·2H2O (1) and [Yb(Hmtbd)(H2mtbd)(H2O)3] (2), were synthesized.
• CP 1 achieved a proton conductivity of 5.09 × 10⁻³ S·cm⁻¹ and CP 2 achieved 3.09 × 10⁻³ S·cm⁻¹ at 100 °C and 98% RH.
• The conductivity of CP 1 is among the highest for lanthanide-based crystalline materials, and CP 2 shows the highest conductivity among reported Yb-CPs.
• Structural analysis and water adsorption data helped determine proton conduction mechanisms.

Conclusions:

• The synthesized lanthanide CPs exhibit significant proton conductivity.
• N-heterocyclic units, carboxyl groups, and hydrogen-bonding networks are key to proton transfer.
• These materials demonstrate potential as efficient proton conductors for various applications.