A Charge-Transfer Salt Featuring a High-Entropy and Plastic Crystal

Area of Science:

• Materials Science
• Crystallography
• Solid-State Chemistry

Background:

• Ionic plastic crystals (IPCs) combine solid-state order with liquid-like molecular dynamics.
• Understanding IPCs is crucial for developing advanced functional materials.

Purpose of the Study:

• To synthesize and characterize a novel charge-transfer salt, [DMIm][Ni(mnt)2] (1).
• To investigate its structural, conductive, and magnetic properties, particularly its phase transition behavior.

Main Methods:

• Single-crystal X-ray diffraction to determine crystal structure.
• Differential scanning calorimetry to study phase transitions.
• Ionic conductivity measurements.
• Magnetic susceptibility measurements.

Main Results:

• Compound 1 undergoes a crystal-to-plastic crystal phase transition at 414 K.
• The low-temperature phase crystallizes in triclinic space group P-1 with complex ionic arrangements.
• Anisotropic dielectric permittivity observed due to layered structure.
• High ionic conductivity of 0.42 S cm-1 achieved in the plastic crystal phase.
• Strong antiferromagnetic interactions observed between anion radicals.

Conclusions:

• The synthesized material exhibits a unique combination of high configurational entropy, superior ionic conductivity, and tunable magnetic properties.
• This work provides a foundation for designing multifunctional molecular materials with integrated properties.