Investigation on structures, luminescent and magnetic properties of Ln(III)-M (M = Fe-HS(II), Co-II) coordination polymers

The structures, luminescent and magnetic properties of three series of coordination polymers with formulas-{[Fe(3)Ln(2)(L-1)(6)(H2O)(6)]center dot xH(2)O}(n) (Ln = Pr-Er; 1-9), {[Co(3)Ln(2)(L-1)(6)(H2O)(6)]center dot yH(2)O}(n) (Ln = Pr-Dy, Yb; 10-17) and {[Co(2)Ln(L-2)(HL2)(2)(H2O)(7)]center dot zH(2)O}n (Ln = Eu-Yb; 18-25) (H2L1 = pyridine-2,6-dicarboxylic acid, H3L2 = 4-hydroxyl-pyridine-2,6-dicarboxylic acid) were systematically explored in this contribution. [Fe-HS(II)-L-1-Ln(III)] (1-9) and [Co-II-L-1-Ln(III)] (10-17) series are isostructural, and display 3D porous networks with 1D nanosized channels constructed by Fe/Co-OCO-Ln linkages. Furthermore, two types of water pipes are observed in 1D channels. [Co-II-L-2-Ln(III)] (18-25) series exhibit 2D open frameworks based on double-stranded helical motifs, which are further assembled into 3D porous structures by intermolecular hydrogen bonds between hydroxyl groups. The variety of the resulting structures is mainly due to the HO-substitution effect. These 3D coordination polymers show considerably high thermal stability, and do not decomposed until 400 degrees C. The high-spin Fe-II ion in [Fe-HS(II)-L-1-Ln(III)] was confirmed by X-ray photoelectron spectroscopy, Mossbauer spectroscopy and magnetic studies. The luminescent spectra of coordination polymers associated with Sm-III, Eu-III, Tb-III and Dy-III were systematically investigated, and indicate that different d-metal ions in d-f systems may result in dissimilar luminescent properties. The magnetic properties of [Fe-HS(II)-L-1-Ln(III)] (3, 6, 7, 9, 13), [Co-II-L-1-Ln(III)] (15-17) and [Co-II-L-2-Ln(III)] (19-24) coordination polymers were also studied, and the chi T-M values decrease with cooling. For the single ion behavior of Co-II and Ln(III) ions, the magnetic coupling nature between Fe-HS(II)/Co-II and Ln(III) ions cannot be clearly depicted as antiferromagnetic coupling.