8-Hydroxyquinoline and Eu³⁺ Incorporated Metal–Organic Framework Nanosystems with Tunable Emissions for White Light and Anticounterfeiting Applications

Metal–organic frameworks (MOFs) are a platform with multiple luminescent centers resulting from the multifaceted nature of their structure. Herein, via a facile postsynthetic modification method applied to the MOF (1,4-dicarboxybenzene, 2,6-pyridinedicarboxylic acid, and zirconium chloride were used as the linkers and metal precursor), the lanthanide-functionalized hybrid nanomaterial Eu3+/MOF(xHQ) (HQ = 8-hydroxyquinoline) is prepared. Luminescence of the Eu3+/MOF(xHQ) nanomaterial was investigated at the excitation wavelength of 308–365 nm, where there are two kinds of luminescence, that is, the MOF(xHQ) emission and the Eu3+ emission. After studying the luminescence of the MOF(xHQ), the luminescence mechanism, that is, the preferential absorption enhancement (PAE) mechanism, was proposed, to reveal the PAE of the MOF over HQ. Notably, the Eu3+/MOF(xHQ) achieves multicolor emissions by changing the excitation wavelength that shows great potential applications in the field of white light materials and anticounterfeiting. Moreover, the PAE mechanism makes the existing MOF more extensive and opens the strategy to the reasonable design of dimming aspects for this type of MOF materials.