A promising MgII-ion-selective luminescent probe:: Structures and properties of Dy-Mn polymers with high symmetry

Two Dy-Mn polymers, {[Dy(L-1)(3)Mn-1.5(H2O)(3)](.)3.125H(2)O}(n) (1, L-1 = pyridine-2,6-dicarboxylic acid) and {[Dy(L-2)(3)Mn-1.5(H2O)(6)]8.25H(2)O}(n) (2, L-2 = 4-hydroxylpyridine-2,6-dicarboxylic acid), with high symmetry (S-6) have been prepared. Polymer 1 has a nanoporous 3D framework with channel of about 17.6 angstrom diameter, while 2 has a honeycomb-type 2D structure with the cavity of approximately 14.4 angstrom 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.