Synthesis, structure, and photophysical property of series of Ln(III) coordination polymers with different carboxylato ligands (Ln = Sm, Eu)

Synthesis, Thermal, Structural Analyses, and Photoluminescent Properties of a New Family of Malonate-Containing Lanthanide(III) Coordination Polymers

Five new Lanthanide(III) complexes of malonic acid (HOOC-CH2-COOH); {[Gd(C3H2O4)(H2O)4]·NO3} n (1), {[Tb(C3H2O4)(H2O)4]·NO3} n (2), {[Ho(C3H2O4)(H2O)4]·NO3} n (3), [Er(C3H2O4)(C3H3O4)(H2O)2] n (4), and {[Eu2(C3H2O4)2(C3H3O4)2(H2O)6]·4H2O} n (5) were synthesized and characterized by elemental, infrared spectral, and thermal analyses. The structures of compounds 1-5 were determined by single crystal X-ray diffraction technique. The X-ray analysis reveals that compounds 1, 2, and 3 are isostructural and crystallized in the orthorhombic space group Pmn21. The lanthanide(III) ions are coordinated by four carboxylate and four water oxygen atoms adopting a distorted square antiprism geometry. The LnO8 square antiprisms are linked into infinite layers by malonate (C3H2O 4 2 - ) dianions sandwiching sheets of nitrate counter ions. Compound 4 contains ErO8 square antiprisms linked into a two-dimensional network by hydrogen malonate (C3H3O 4 - ) anions and malonate dianions. The europium complex, 5 is dinuclear having the two europium(III) ions (Eu1 and Eu2) bridged by carboxylate groups of hydrogen malonate ligands. The europium ions in 5 are nine-coordinate and exhibit a distorted monocapped square antiprism geometry. All the structures are consolidated by O-H⋯ O hydrogen bonds. The photoluminescence spectra of 1-5 exhibit characteristic emissions in the visible region. The IR spectra and thermal data are consistent with the structural results. The room-temperature effective magnetic moments for 1-4 are in good agreement with those expected for the free ions, while the data for 5 indicates that low-lying excited states contribute to the observed moment. The compound 1 was further subjected to quantum computational calculations to explore its optoelectronic properties including; density of states (DOS), dielectric function, refractive index, extinction coefficient, and absorption spectrum, to highlight the possible applications of such materials in the optoelectronics.

Crystal growth and structural remarks on malonate-based lanthanide coordination polymers

The synthesis, structural and thermal studies of several malonate-containing lanthanide(iii) complexes plus a structural overview of twenty-three known homometallic Ln(iii)-malonate systems are provided herein.