A new two-dimensional layered germanate with in situ embedded carbon dots for optical temperature sensing

Abstract

A new germanate |H₂(C₄N₃H₁₃)|₃[Ge₇O_14.5F₂][Ge₇O₁₄F₃]·2.5H₂O (denoted as JLG-16) has been synthesized by using diethylenetriamine as the structure-directing agent under solvothermal conditions. Single-crystal structural analysis reveals that JLG-16 crystallizes in the monoclinic space group C2/c with a = 38.2008(15) Å, b = 8.8262(4) Å, c = 31.1789(13) Å, and β = 108.5470(10)°. Its structure is made up of 4- and 5-coordinated Ge₇ clusters. The alternating connection of 4- and 5-coordinated Ge₇ clusters gives rise to a double-layered structure with 16- and 10-ring channels and a low framework density (11.2 Ge per 1000 ų). Carbon dots (CDs) formed in the mother liquid are in situ embedded into the JLG-16 crystals during the solvothermal crystallization process. The resulting CDs@JLG-16 composite thus exhibits excitation-dependent and temperature-responsive photoluminescence performances, which makes it possible to be used in optical temperature sensing.