Hydrothermal synthesis, structural investigation, and magnetic properties of 2-D layered lanthanide (Ln = Pr, Eu, Gd, Tb, and Er) coordination polymers possessing infinite 1-D nanosized cavities

Abstract

Tetrahedral SBUs to construct 2D net having nanosized cavities.Five 2-D Ln(III) coordination polymers, [Ln(PDA)(PDAH)] n (PDA = 2,6-pyridinedicarboxylate), have been obtained under mild hydrothermal condition. In each coordination polymer, PDA is tetradentate and pentadentate, while lanthanides have coordination number eight to generate trigonal prismatic, triangular face bicapped LnO 6 N 2 geometry having 9 triangular and 2 square faces. Two different types of bridging oxygens are responsible to grow the 2-D coordination polymers providing open channels possessing infinite 1-D nanosized cavities. Adjacent 2-D chains are further extended to a 3-D hydrogen-bonded layered network through intermolecular π-π interactions and C-H⋯O hydrogen bonds. Four lanthanides are arranged roughly at the vertices of a square and bridged by eight carboxylates leading to the overall tetrahedral shape of the secondary building units. The abnormal behavior of lanthanide contraction for the atomic radii of europium can be attributed to overlapping of electron clouds. The overall magnetic behavior is typical for the presence of antiferromagnetic exchange coupling interactions. Thermal decomposition analysis reveals that the coordination polymers have significant thermal stability. The coordination polymers are further characterized using elemental analysis and FT-IR spectroscopy.

Complexes of Eu(III), Tb(III) and Cu(II) with proton transfer compound between 2,6-pyridinedicarboxylic acid and 2-aminobenzothiazole: characterization of the structures and physical properties

“…These ladder structures are connected to each other via hydrogen bonds. Similar structures were reported for a series of [ln(Pydc)(PydcH)] n complexes (ln = Pr, Eu, Gd, Tb, Er) prepared by hydrothermal synthesis [38]: each ln(III) is eight-coordinate by two nitrogens and four oxygens from Pydc ligands and two oxygens from bridging carboxylate groups, generating an infinite 1-D (ln-OCO-ln-OCO-ln) n wavelike chain motif. Adjacent 1-D chains are interconnected into ordered 2-D layered structures.…”

Synthesis, crystal structure and magnetic properties of an octanuclear cerium(III) complex of pyridine-2,6-dicarboxylate

“…The asymmetric mode, ν as (COO) of the free ligand at 1688 cm −1 is shifted towards lower wavenumbers upon coordination (1645 cm −1 ), showing that the ligand is coordinated to the metal through the carboxylate oxygen atoms. The symmetric mode, ν s (COO) appears at higher wavenumber (1420 cm −1 ) with respect to the free ligand (1375 cm −1 ) [27]. The characteristic bands at 1585, 1475, and 960 cm −1 can be assigned to the stretching and bending vibrations of the pyridine rings.…”

“…Among the multidentate ligands, pyridine-2,6-dicarboxylic acid (H 2 Pydc) is widely applied as a bridging ligand to construct lanthanide-based metal-organic frameworks [21][22][23][24][25]. We were interested to explore the use of H 2 Pydc in developing supramolecular structures with different lanthanide(III) ions under appropriate conditions [26][27][28]. As an extension of such studies, we report here the synthesis, crystal structure, and magnetic properties of an octanuclear cerium(III) complex of Pydc.…”

Synthesis, Crystal Structure, Thermal, Magnetic Properties and DFT Computations of a Ytterbium(III) Complex Derived from Pyridine-2,6-Dicarboxylic Acid

“…The characteristic absorptions for the asymmetric and symmetric stretches of carboxylate group are found at 1607 and 1447 cm −1 respectively, while in the IR spectrum of free ligand, these bands are observed at 1688 and 1375 cm −1 respectively. A signi cant shift of the asymmetric mode, ν as (COO) towards the lower wavenumber upon coordination and that of the symmetric mode, ν s (COO) towards the higher wavenumber indicates the binding of Pydc ligand to the metal through the carboxylate oxygen atoms [20].…”