Zn/Cd/Cu- frameworks constructed by 3,3′-diphenyldicarboxylate and 1,4-bis(1,2,4-triazol-1-yl)butane: Syntheses, structure, luminescence and luminescence sensing for metal ion in aqueous medium

Three metal-organic frameworks (MOFs), [M(dpdc)(btb)0.5](n) (M = Zn 1, Cd 2; dpdc = 3,3'-diphenyldicarboxylate and btb = 1,4-bis(1,2,4-triazol-1-yl)butane) and [Cu-3(dpdc)(3)(btb)21, (3) were prepared and structurally determined. 1 is a 2D structure with the topology of {3(3)4(7).5(4).6}, while 2 possesses a 3D framework with the {3(12).4(29).5(14)} topology. Complex 3 displays a 3D framework with the topology of {3(15).4(35).5(5)}2{3(6).4(8).5(12).6.7}. 1-2 exhibit intense blue luminescence and high stability in water, which make them highly promising candidates as sensors using in aqueous medium. Complex 1 is a potential bi-functional chemosensor for Fe3+ and Al3+ ions while 2 displays a selective sensing ability to Fe3+ ion. Quenching mechanism of Fe3+ on the luminescence of 12 is attributed to the charge transfer process LMCT. 1 and 2 have same compositions but have different structures, thermally stabilities and different luminescence sensing functions. The relationship between MOF structures and luminescence sensing toward metal ions are further discussed.