New Family of Luminescent Tetranuclear Lanthanide-Based Germsesquioxanes: Luminescence and Temperature Sensing

We report the synthesis, structures, magnetic, and luminescence properties of a new series of tetranuclear lanthanide-based germsesquioxanes [NEt4]2[(Ph4Ge4O8)2(Ln4)(NO3)6(EtOH)2(MeCN)2]·n(CH3CN) (where Ln = Eu3+ (1), Tb3+ (2), Tb3+/Eu3+ (3), Dy3+/Y3+ (4), and Dy3+ (5)). These paramagnetic compounds exhibit characteristic Ln3+-based emission in solid state at room and liquid nitrogen temperature. Temperature-dependent luminescence investigated between 293 and 373 K reveals that mixed Tb3+/Eu3+ (3) compound works as a self-referenced ratiometric optical thermometer with a maximum relative sensitivity of 0.87%·°C-1 achieved at 57.6 °C. © 2023 American Chemical Society.