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A Promising MgII-Ion-Selective Luminescent Probe: Structures and Properties of Dy–Mn Polymers with High Symmetry



Two Dy–Mn polymers, {[Dy(L1)3Mn1.5(H2O)3]⋅3.125 H2O}n (1, L1=pyridine-2,6-dicarboxylic acid) and {[Dy(L2)3Mn1.5(H2O)6]⋅8.25 H2O}n (2, L2=4-hydroxylpyridine-2,6-dicarboxylic acid), with high symmetry (S6) have been prepared. Polymer 1 has a nanoporous 3D framework with channel of about 17.6 Å diameter, while 2 has a honeycomb-type 2D structure with the cavity of approximately 14.4 Å diameter. In the construction of multidimensional porous polymers with 3d–4f mixed metals, it is the first observation that a ligand substituent effect leads to dramatic differences in the structures formed. Luminescent studies reveal that the emission intensities of 1 and 2 increase significantly upon the addition of Mg2+, whereas the introduction of other metal ions leaves the intensity unchanged or even weakens it; hence, both of them may serve as good candidates of Mg2+ luminescent probes. To our knowledge, complex 1 is also the first example of a 3d–4f metal-based nanoporous polymer to exhibit luminescent selectivity for Mg2+. Magnetic susceptibility measurements reveal a rather rare ferromagnetic interaction in 2. Thermal gravimetric analyses and powder X-ray diffraction investigations have also been performed, suggestive of high thermal stability of 1.