Antenna Effect in Halogen‐Containing ZnSm Coordination Compounds: Utilizing Colorimetry for a Room‐Temperature Tunable Ratiometric Molecular Thermometer

ABSTRACT Temperature‐dependent photoluminescence (TDPL) is an efficient optical characterization method. Compared to traditional ratiometric photothermal instruments that rely on doped materials and suffer from poor reproducibility, molecular ratiometric thermometers offer advantages such as high precision, fast response, remote temperature measurement capability, and good optical stability. We synthesized three halogen‐substituted bimetallic coordination compounds using a one‐pot method, which showed good reproducibility. The molecular complexs are abbreviated as ZnSm‐X (X = Cl, Br, I). Importantly, ZnSm‐X with different halogen substitutions exhibit different temperature dependencies at 253–333 K. Among them, the ZnSm‐Cl has a relative sensitivity of 12.14% K ⁻¹ at 268 K. This is attributed to the well‐matched relative energy levels between ligand and Sm ³⁺ , which facilitate energy transfer from the triplet state of the ligand to the excited state of Sm ³⁺ , resulting in temperature‐dependent photoluminescence. By using colorimetry, the temperature‐dependent photoluminescence of ZnSm‐Cl complexes within a room‐temperature adjustable range will provide new ideas for molecular ratiometric thermometers.