Terbium-modified two-dimensional zirconium-based metal-organic frameworks for photoluminescence detection of nitrite

In this study, spatially isolated terbium ions are post-synthetically installed on a two-dimensional (2D) water-stable zirconium-based metal-organic framework (MOF), ZrBTB (BTB = 1,3,5-tri(4-carboxyphenyl)benzene), and the loading of installed terbium ions is adjusted by tuning the synthetic temperature of the post-synthetic process. The crystallinity, porosity, morphology, chemical state, and terbium loading of the obtained materials are characterized. Tb-modified MOFs synthesized at various temperatures were subjected to photoluminescence tests in aqueous environments, and the energy transfer from the BTB linkers to the installed terbium sites is highly tunable by adjusting the temperature for installing terbium. Since the photoluminescence of the installed terbium sites can be quenched by the nitrite ions present in the solution, as a demonstration, the terbium-incorporating MOFs are applied for nitrite quantification by utilizing the Stern-Volmer equation; a high Stern-Volmer constant of 472 000 M⁻¹ and a low limit of detection of 0.08 μM can be achieved.