Two New NIR Luminescencent Er(III) Coordination Polymers with Potential Application Optical Amplification Devices

Synthesis, Structural, Magnetic and Computational Studies of A One-Dimensional Ferromagnetic Cu(II) Chain Assembled from a New Schiff Base Ligand

A new asymmetrically substituted ONOO Schiff base ligand N-(2′-hydroxy-1′-naphthylidene)-3-amino-2-naphthoic acid (nancH2) was prepared from the condensation of 2–hydroxy–1–naphthaldehyde and 3–amino–2–naphthoic acid. nancH2 reacts with Cu2(O2CMe)4·2H2O in the presence of Gd(O2CMe)3·6H2O to afford a uniform one-dimensional homometallic chain, [CuII(nanc)]n (1). The structure of 1 was elucidated via single crystal X-ray diffraction studies, which revealed that the Cu(II) ions adopt distorted square planar geometries and are coordinated in a tridentate manner by an [ONO] donor set from one nanc2− ligand and an O− of a bridging carboxylate group from a second ligand. The bridging carboxylato group of the nanc2− ligand adopts a syn, anti-η1:η1:μ conformation linking neighboring Cu(II) ions, forming a 1D chain. The magnetic susceptibility of 1 follows Curie–Weiss law in the range 45–300 K (C = 0.474(1) emu K mol-1, θ = +7.9(3) K), consistent with ferromagnetic interactions between S = ½ Cu(II) ions with g = 2.248. Subsequently, the data fit well to the 1D quantum Heisenberg ferromagnetic (QHFM) chain model with g = 2.271, and J = +12.3 K. DFT calculations, implementing the broken symmetry approach, were also carried out on a model dimeric unit extracted from the polymeric chain structure. The calculated exchange coupling via the carboxylate bridge (J = +13.8 K) is consistent with the observed ferromagnetic exchange between neighbouring Cu(II) centres.

Synthesis and microstructure of Al2O3 aerogel composite induced by different transition/lanthanide metal ions

The study of the influence of different substances introduced on the same matrix will provide a good guide for the construction of materials with good properties. A series of transitions/lanthanides metal ions doped or co-doped Al2O3 aerogel materials with three-dimensional nano porous structure were fabricated by a simple and facile modified sol-gel method. The effect of different transitions/lanthanides metal ions on the microstructure, textural properties, and luminescence properties of Al2O3 aerogels were investigated. By co-doping the Al2O3 aerogel matrix with Eu3+ and Tb3+, we fabricated Al2O3 aerogel luminescent materials with tunable color emissions under UV excitation. The characterization results showed that the microscopic morphology of these aerogels induced by transitions/lanthanides metal ions were obviously different. Interestingly, Al2O3-Eu/Tb (III) and Al2O3-Tb/Ce (III) aerogels exhibited a special flower-like structure. It is hoped that our work will offer some efforts for the preparation of functional materials with excellent properties.

Recent Advances of Near-Infrared (NIR) Emissive Metal Complexes Bridged by Ligands with N- and/or O-Donor Sites

Near-infrared (NIR) emissive metal complexes have shown potential applications in optical communication, chemosensors, bioimaging, and laser and organic light-emitting diodes (OLEDs) due to their structural tunability and luminescence stability. Among them, complexes with bridging ligands that exhibit unique emission behavior have attracted extensive interests in recent years. The target performance can be easily achieved by NIR light-emitting metal complexes with bridging ligands through molecular structure design. In this review, the luminescence mechanism and design strategies of NIR luminescent metal complexes with bridging ligands are described firstly, and then summarize the recent advance of NIR luminescent metal complexes with bridging ligands in the fields of electroluminescence and biosensing/bioimaging. Finally, the development trend of NIR luminescent metal complexes with bridging ligands are proposed, which shows an attractive prospect in the field of photophysical and photochemical materials.

Coordination polymers based on trans, trans-muconic acid: synthesis, structure, adsorption and thermal properties

Metal-organic frameworks (MOFs) are promising sacrificial templates for synthesis of carbon functional materials with a relatively high concentration of stabilized metallic species. In this work coordination polymers based on trans,trans-muconic acid and transition metals (Cu, Zn, Ni, Co) were prepared and selected as the precursors for supramolecular organization of nanocomposites. The coordination polymers and metal-containing thermolysis products obtained were characterized using a number of analytical techniques including powder X-ray diffraction, elemental analysis, thermal gravimetric analysis, scanning electron microscopy and volumetric nitrogen adsorption/desorption. This study extends the application of coordination polymers as precursors for designing of carbon materials incorporating metal nanoparticles. It is shown that appropriate choice of metal-organic precursors in solid-phase thermolysis allowed to get materials with determined morphologies.

Eu@PMMA and Sm@PMMA nanofibers prepared by electrospinning: structure, morphology, luminescence and magnetic properties

Eu³⁺ and Sm³⁺ coordination polymers and a series of Eu@PMMA and Sm@PMMA nanofibers were prepared. Color tunability was achieved with the luminescence changing from reddish orange in the bulk state to near-white light in the nanofiber stage.