A Zn (II)-viologen MOF material: Photochromic, photoswitchable luminescent properties and UV sensing

In this study, one Zn-viologen complex, named [Zn3(Hbdpd)(bdpd)(Cl)(Bbpy)] (1) (BbpyCl2 = 1,1′'-[(4,4′-biphenylylene)bismethylene]bis(4,4′-bipyridine)·2chloride; H4bdpd = 2,6-bis (3′,5′-dicarboxyphenyl) pyridine) has been constructed via a self-assembly method. Compound 1 features a 3D pillared layer dense framework and shows excellent photochromic properties from yellow to blue when exposed to 365 nm light at intensity of 500 µw/cm2 for 30 min. More interestingly, complex 1 displays light green fluorescence with quantum yield of 6.1% and reversible naked-eye photoswitchable luminescence at room-temperature in the solid state upon 365 nm UV excitation. Based on the multicolor photochromic behavior and photoswitchable luminescent property of compound 1, the finely powdered sample has the potential application for UV detection in real world.