Manganese(III)-containing ionic liquids with liquid crystalline properties: Synthesis, structural insights, and functional applications

The development of multifunctional materials combining thermal stability, magnetic behavior, and liquid crystalline properties remains a critical challenge in advanced material science. Addressing this, the present study explores a novel manganese-based ionic liquid complex, [Mn(cyclam)(4-CH₃(CH₂)₉OC₆H₄COO)₂].(4-CH₃(CH₂)₉OC₆H₄COO).2H₂O, featuring long-chain ester ligands and pseudohalide coordination. The central research question investigates how strategic ligand selection influences the structural, thermal, and magnetic properties of heavy metal-assisted ionic liquids. The synthesized complex was characterized using FTIR and UV-Vis spectroscopy, which confirmed the distorted octahedral geometry of the Mn(III) ion through electronic transitions at 434 nm and 1381 nm. Thermal analysis via thermogravimetric analysis (TGA) revealed high stability, with decomposition beginning at 242 °C, while differential scanning calorimetry (DSC) detected two phase transitions at 95 °C and 115 °C. Polarized optical microscopy (POM) identified an ordered mesophase, affirming the complex's liquid crystalline behavior. Magnetic measurements indicated a high-spin d⁴ configuration with a magnetic moment of 4.6 B.M. The novelty of this work lies in its molecular design—specifically, the use of cyclam and long-chain carboxylate ligands to enhance both stability and mesogenic properties. These findings underscore the potential of this Mn(III) complex for optoelectronic, catalytic, and smart material applications, providing a platform for future research focused on tuning optical and rheological properties through ligand engineering. • Synthesis and characterization of a novel manganese-based ionic liquid complex [Mn(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO).2H 2 O. • Confirmation of distorted octahedral coordination of Mn(III) ions through spectroscopic studies. • Excellent thermal stability with a decomposition temperature of 242 °C. • Observation of liquid crystalline behavior with distinct phase transitions.