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A new photochromic metal organic frameworks (MOFs) have been synthesized by using a viologen ligand, named 1,1′-bis(3,5-carboxylatobenzyl)-(4,4′-bipyridinium) dichloride (H 4 bdcbpy•2Cl) and Cd(NO 3) 2 ·4H 2 O. This MOF (Cd-bdcbpy) features a three-dimensional (3D) framework structure, exhibiting photochromic properties under the irradiation of white light, blue light, UV light and heat with obvious color change from light yellow to dark green. Meanwhile, Cd-bdcbpy displays a visible color change to the naked eye when exposed to different organic amine molecules (ammonia, aniline, o-methylaniline and diphenylamine). Moreover, the detection of ammonia has been confirmed by the visual color changing phenomenon and luminescence quenching experiment and it can detect ammonia in very low concentrations (10-6 ​M). Attractively, through luminescence quenching, Cd-bdcbpy can be used as a multi response sensor for Cr 2 O 7 2− anion in aqueous solution. Complex 1 shows high sensitivity to UV, sunlight white light, blue light and heat. It is selective and sensitive to different amine vapors through color change. It can be used as a Cr 2 O 7 2− detector. [Display omitted] • A novel photochromic metal organic framework was prepared under solvothermal conditions. • Complex 1 shows high sensitivity to UV, sunlight white light, blue light and heat. • Complex 1 exhibits amine selective sensing and Cr 2 O 7 2− detection. [ABSTRACT FROM AUTHOR]