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A novel europium metal-organic frameworks (Eu-MOFs), based on 1,3,5-benzotricarboxylic acid (H 3 BTC), 4,4′-azopyridine (4,4′-AZ) and N , N -dimethyllformamide (DMF), was synthesized by the solvothermal method. The crystal structure, thermal stability, morphology and luminescent properties are characterized by the X-ray diffraction (XRD), thermogravimetry (TG), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and optical spectroscopic techniques. The Eu-MOFs display a unique luminescence quenching effect to nitrobenzene (NB) and copper (Cu2+) ions. The turn-off luminescence can be induced by 210 ​ppm NB or by 1000 ​μM Cu2+ ions. Furthermore, the high sensitivities (K SV ​= ​0.039 ​ppm−1 for NB, and K SV =0.029 ​μM−1 for Cu2+) and low detection limits (0.656 ​ppm for NB, and 1.395 ​μM for Cu2+) are obtained. The sensing mechanisms are reasonably explained based on the electron and energy transfer. The experimental results show that the Eu-MOFs can be used as a potential sensing luminescence quenching probes for NB and Cu2+ ions. Figure. (a) Three dimensional structure of Eu-MOFs,(b) coordination environment around Eu3+, and (c) coordination mode of H 3 BTC [Display omitted] • Eu(III) metal-organic-framework (Eu-MOF) fluorescent probe was solventhermally synthesized. • Eu-MOF probe can sensitively and selectively detect nitrobenzene and Cu2+ ions. • The mechanism of sensing properties were investigated and discussed in details. • Eu-MOF can be used as a potential luminescence quenching material in practical application. [ABSTRACT FROM AUTHOR]