Multifunctional luminescent magnetic cryocooler in a Gd5Mn2 pyramidal complex. Issue 33 (16th February 2018) - Huang, Wei
Abstract : A [GdIII5MnII2] pyramidal complex was developed for multifunctional PL, ML, and MCE applications involving red-light sources, thermometers, and stress imaging. In particular, this provides a novel resolution to design a visualized PL cooler. Abstract : Magnetic cooling is a highly efficient refrigeration technique with the potential of replacing expensive and rare helium-3 in the field of ultra-low temperature cooling. However, the visualization of a cryogen at an extremely low temperature and in a strong magnetic field is challenging, but it is crucial for the precise positioning and in situ thermal probe measurements in potential practical applications. Here, the activation of a red-emissive Mn(ii ) ion using 3d/4f chemistry produces a luminescent molecule cooler, [Gd5 Mn2 (L OMe )2 (OH)4 (Ac)6 (MeOH)10 Cl2 ]Cl3 ·2MeOH (1 ), with the core of an Mn(ii )-anchored heptanuclear [GdIII5MnII2] pyramid. The photoluminescence (PL) of the Mn 2+ emission, with a large Stokes shift ( λ em ∼ 690 nm) from 4 T1 ( 4 G) → 6 A1 ( 6 S), shows not only a sensitive temperature sensing property but also reversible mechanoluminescence (ML). More attractively, these findings reveal a considerable magnetocaloric effect (MCE) coupled with a tunable emission window, opening up new opportunities in the multifunctional applications of PL, ML, and the MCE involving red-light sources, thermometers, and stress imaging. In particular, this provides a novel resolution to design visualized PL coolers.