A Luminescent Sensing Experiment of Cage-like Europium-Germanate Oxo Cluster for Advanced Undergraduate Students

To improve the experimental interest and innovative ability of advanced undergraduate students, a luminescent sensing laboratory experiment with visual performance characteristics is introduced. Students have synthesized an organic hybrid cage-like europium-germanate oxo cluster with the formula of [Eu-8(phen)(2)Ge-12(mu(3)-O)(24)(CH2CH2COO)(12)(H2O)(16)]2phen14H(2)O (Eu8Ge12, phen = 1,10-phenanthroline) by a facile solvothermal reaction of phen, Eu2O3 and bis(carboxyethylgermanium)-sesquioxide in H2O solution at 150 degrees C and structurally characterized by single crystal X-ray diffraction. The luminescence and luminescent sensing properties of Eu8Ge12 are analyzed visually by naked eye and ultraviolet lamp and quantitatively by a fluorimeter, revealing that Eu8Ge12 can not only exhibit a bright red-light emission but also show a good potentiality serving as a dual-responsive sensor for the detection of Fe3+ and Cr2O72- ions, due to the existence of the rare free phen with Lewis basic N-donor. This experiment design is very essential to (a) gain the profound understanding of students in the crystal structure of the new complicated cage and its structure-property-application relationship, (b) cultivate students' innovative ability of scientific research by the utilization of modern analytical instruments, and (c) encourage students to develop the new detection method for the actual target ions by the exploration of the luminescent sensing properties, thereby enhancing their comprehensive experimental skills.