Temperature-controlled optical response characteristic of an ionic liquid-based neodymium complex

Lanthanide-based metal-organic coordination polymers (Ln-MOCPs) have been widely used in luminescent temperature sensing. Among them, Nd³⁺ has become a highly promising luminescent center due to its intense radiative transition properties in the first and second near-infrared regions. In this work, {[NdIMDC(H₂O)₄]Cl₂.2H₂O} _n (NdIMDC, IMDC = C₇H₇N₂O₄) was synthesized using Brønsted acidic ionic liquid, 1,3-bis(carboxymethyl)imidazolium chloride ([H₂IMDC]Cl), as light-harvester. The crystal structure of NdIMDC was characterized by single-crystal X-ray diffraction (SCXRD), its composition and morphology were determined by fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM), and its thermal stability is evaluated by thermogravimetric analysis (TGA). The temperature-dependent luminescence properties of NdIMDC were assessed with the relative sensitivity (Sr) and temperature uncertainty (ΔT) of 0.618% K^-1 and ±0.29 K. These findings confirm that NdIMDC establishes a well-defined linear relationship between its characteristic emission intensity ratio and temperature, suggesting its promising application in near-infrared luminescent temperature sensing.