A new metal - organic framework [Zn-5(hfipbb)(4)(trz)(2)(H2O)(2)] (NNU-1) [H(2)hfipbb = 4,4'-(hexafluoroisopropylidene)bis(benzoic acid), Htrz = 1H-1,2,3-triazole] was assembled by hydrothermal synthesis. Single-crystal X-ray diffraction analysis reveals that NNU-1 displays a twofold interpenetrating three-dimensional (3D) framework with a {4(24).6(4)}-bcu topology. Interestingly, the 3D framework contains a two-dimensional (2D) layered structure that consists of alternating left- and right-handed double helical chains. On the basis of the hydrophobic -CF3 groups from H(2)hfipbb ligand, NNU-1 possesses excellent stability in water. It is worth noting that NNU-1 not only shows a highly selective fluorescence quenching effect to Fe3+ ion in aqueous solution but also resists the interference of other metals including Fe2+ ion. Accordingly, NNU-1 probably functions fluorescence sensor for detecting Fe3+ ion with high sensitivity and selectivity.