Water-free rare-earth-metal ionic liquids/ionic liquid crystals based on hexanitratolanthanate(III) anion

Area of Science:

• Inorganic Chemistry
• Materials Science
• Crystallography

Background:

• Ionic liquids offer unique solvent properties, but water-free systems are less explored.
• Lanthanum nitrate complexes present an opportunity for novel ionic liquid development.

Purpose of the Study:

• Synthesize and characterize novel water-free lanthanum nitrate ionic liquids.
• Investigate the structural, thermal, and liquid-crystalline properties of these compounds.

Main Methods:

• Synthesis of eleven hexanitratolanthanate complexes with varying alkyl chain lengths.
• Characterization using NMR, IR spectroscopy, elemental analysis, and X-ray diffraction.
• Thermal stability assessed by TGA; liquid crystallinity studied by DSC and POM.

Main Results:

• Eleven new hexanitratolanthanate complexes, [C(n)mim]3[La(NO3)6], were successfully synthesized and characterized.
• Crystal structure of [C1mim]3[La(NO3)6] revealed a coordination polyhedron with twelve oxygen atoms and no water.
• Four complexes (n=12, 14, 16, 18) exhibited ionic liquid crystal behavior with a smectic A phase.

Conclusions:

• Water-free hexanitratolanthanate ionic liquids are thermally and moisture stable.
• The alkyl chain length influences the liquid-crystalline properties of these lanthanum complexes.
• These novel materials hold promise for applications requiring stable, water-free ionic liquids with liquid-crystalline phases.