A Mg-CP with in Situ Encapsulated Photochromic Guest as Sensitive Fluorescence Sensor for Fe/Cr Ions and Nitro-Explosives.

Here we report a fluorescent magnesium coordination polymer (Mg-CP), namely, [CH-dpb][Mg(1,4-NDC)(μ-HO)(CHOH)(HO)]·1.5HO (1, 1,4-HNDC = 1,4-naphthalene dicarboxylic acid, dpb = 1,4-bis(pyrid-4-yl)benzene). Compound 1 possesses a three-dimensional (3D) host-guest structure constructed by the 1,4-NDC linkers bridging the linear trinuclear secondary building units of [Mg(COO)(μ-HO)]. The dpb molecules were in situ reacted with CHOH resulting in photochromic cations of [CH-dpb] that acted as guests located in the channels parallel to the b-axis. Photoluminescence (PL) studies indicated that 1 showed a strong green emission demonstrating sensitive fluorescence sensing of Fe/Cr metal ions and nitro-explosive compounds. Compound 1 represents the first PL Mg-CP as a fluorescent probe for detecting metal ions. Moreover, because of the in situ encapsulation of photochromic [CH-dpb] guests, 1 exhibited reversible photochromic behavior.