Synthesis, structure and properties of 2D lanthanide coordination polymers based on N-heterocyclic arylpolycarboxylate ligands

Abstract

The reaction of 3-(2,4-dicarboxyphenyl)-2,6-pyridinedicarboxylic acid (H4dppd) with rare earth nitrates under hydrothermal conditions generated a series of new two-dimensional (2D) coordination polymers, namely {[La(Hdppd)(H2O)2·(H2O)2]n (1), [Ln2(Hdppd)2(H2O)4·(H2O)3]n [Ln = Sm (2), Eu (3)] and [Ln(Hdppd)(H2O)3·H2O]n [Ln = Gd (4), Tb (5), Dy (6), Ho (7), Er (8)] [Hdppd = 3-(2,4-dicarboxyphenyl)-2,6-pyridinedicarboxylic trivalent anion]}. The complexes were characterized by X-ray single-crystal diffraction, infrared spectroscopy, elemental analysis and thermogravimetric analysis. Luminescence spectroscopy of 3 and 5 showed bright red and green luminescences due to the 4f(n)-4f(n) transitions in Eu(3+) and Tb(3+) respectively, although the luminescence lifetime is shortened by non-radiative decay due to the presence of coordinating water molecules. The magnetic properties of 2-8 were measured and discussed. Compound 6 exhibits frequency dependent out-of-phase signals, and ferromagnetic coupling exists in 8.

A series of new lanthanide complexes with 2‐bromo‐5‐methoxybenzoic acid and 5,5′‐dimethyl‐2,2′‐bipyridine: Crystal structures, thermal behavior, luminescent and magnetic properties

“…The 5,5′‐DM‐2,2′‐bipy ligand chelates the Tb 3+ ion center with two Tb1‐N (N1 and N2) lengths of 2.561(6) Å and 2.601(7) Å, respectively. The average bond distances of Tb1‐O and Tb1‐N are 2.450 Å and 2.581 Å, respectively, which are within the bond distances of Tb‐O and Tb‐N of the previous terbium complexes . Each independent binuclear unit is linked together by weak C‐H···Br hydrogen bonding between carbon atoms of bridging bidentate 2‐Br‐5‐MOBA ligand and bromine atoms of chelating bidentate 2‐Br‐5‐MOBA ligand to form an infinite 1D chain along the b axis (Figure a).…”

Construction of lanthanide complexes supported by 2,3‐dimethoxybenzoic acid and 5,5’‐dimethy‐2,2’‐bipyridine: crystal structures, thermoanalysis, magnetic and fluorescence properties

“…Rare‐earth complexes have attracted much interest for their wide application in many fields because of not only their abundant chemical, physical properties and intriguing architectures, but also their potential applications such as luminescent sensing, molecular magnetism, and catalysis fields . For photoluminescence, rare‐earth ions are usually used as luminescent centers for their high luminescence efficiency and adjustable emission color .…”

Silver(I) coordination polymers assembled from flexible cyclotriphosphazene ligand: structures, topologies and investigation of the counteranion effects

“…Over the past two decades, coordination polymers have attracted a great deal of attention from researchers due to their intriguing variety of structures (Zhang et al, 2012;Khlobystov et al, 2001;Robin & Fromm, 2006), topologies (Batten et al, 2009;Hong & Chen, 2009) and promising applications in materials science (You et al, 2014;Beobide et al, 2006;Wang et al, 2014;Cui et al, 2012;Suh et al, 2012;Sumida et al, 2012) such as luminescence, magnetism, catalysis and gas storage. Despite remarkable progress on theoretical approaches in the structural prediction of transition metal complexes (Minenkov et al, 2012;Zhang et al, 2008;Berces, 1997;Kim & Kim, 2012), predicting the structure of coordination polymers remains one of the most challenging issues in coordination chemistry caused by various factors such as ISSN 2052-5206 # 2016 International Union of Crystallography ligand type (Mu et al, 2012), M/L ratio (Guo et al, 2013), metal centers (Masu et al, 2006), counterions (Wang et al, 2009), solvents (Li & Du, 2011), pH (Yu et al, 2009) and temperature (Forster et al, 2004).…”