Syntheses, crystal structures and magnetic properties of a series of luminescent lanthanide complexes containing neutral tetradentate phenanthroline-amide ligands

Abstract

Six lanthanide compounds have been prepared from a neutral tetra-dentate ligand. Their luminescent and magnetic properties were investigated in detail.

High-Coordinate Mononuclear Ln(III) Complexes: Synthetic Strategies and Magnetic Properties

“…None of these complexes showed any peaks in the frequency-dependent out-of-phase (χ″) AC magnetic measurements at 2 K even at high frequency. Modifying the phenanthroline backbone Lau and co-workers synthesized a phenanthrolineamide ligand, N 2 ,N 9 -dibutyl-1,10-phenanthroline-2,9-dicarboxamide (L2) [48]. In comparison to the ligands discussed above, L2 is now a tetradentate ligand symmetrically substituted by amide functionalities at the 2 and 9 positions of the phenanthroline moiety.…”

“…In comparison to the ligands discussed above, L2 is now a tetradentate ligand symmetrically substituted by amide functionalities at the 2 and 9 positions of the phenanthroline moiety. The reaction of L2 with Ln(NO3)3•6H2O in MeOH in the presence of NaClO4•H2O afforded three isostructural mononuclear complexes, [Ln(L2)2(NO3)](ClO4)2 (Ln = Eu (22), Sm (23), Tb (24) and Dy ( 25)) [48]. The ten-coordinate geometry of Ln(III) in 22-25 resulted from the coordination of four N atoms and four O atoms from two L2 ligands, and two O atoms from a κ 2 O-nitrate (Figure 13).…”

“…It was surprising that complex 24 showed two maxima in the out-of-phase(χ″) susceptibility component below 3 K while only one maximum was observed in the temperature range 3 to 5.5 K. The double relaxation behavior was further confirmed in the Cole-Cole plots with two obvious semicircles. The complex relaxation behavior of 24 was analyzed considering three relaxation processes namely Raman, Orbach, and quantum tunneling, following the equation, Modifying the phenanthroline backbone Lau and co-workers synthesized a phenanthroline-amide ligand, N 2 ,N 9 -dibutyl-1,10-phenanthroline-2,9-dicarboxamide (L2) [48]. In comparison to the ligands discussed above, L2 is now a tetradentate ligand symmetrically substituted by amide functionalities at the 2 and 9 positions of the phenanthroline moiety.…”

“…(a,b) Perspective viewings for the cationic structures of 24 and 25, (c,d) frequency dependence of in-phase (χ ) and out-of-phase (χ") AC magnetic susceptibility for 24 and 25 under a 1.5 kOe (for 24) and 1.0 kOe (for 25) DC field, and (e,f) the ln(τ) vs. T −1 plots for 24 and 25 (red lines are the best fits). Figures and captions are reproduced from Reference[48] with permission from the Royal Society of Chemistry.…”

Multifunctional Binuclear Ln(III) Complexes Obtained viaIn SituTandem Reactions: Multiple Photoresponses to Volatile Organic Solvents and Anticounterfeiting and Magnetic Properties

“…Molecular-based multifunctional materials give two or more functions to a molecular entity and have received considerable attention for more than a decade because of their potential applications in different fields. − A molecular-based crystalline multifunctional material is easy to process and modify due to its specific shape, crystalline state, and fixed melting point. , The search for and selection of ideal candidates for constructing molecular-based crystalline multifunctional materials have been a considerable challenge. ,,− Due to their the complex and variable coordination modes, high coordination numbers, and flexible geometric configurations of lanthanide metal ions, lanthanide metal complexes show structural diversity. − Furthermore, because of the special 4f n electronic structure of lanthanide metal ions, Ln­(III) complexes have optical and magnetic properties that are considerably different from those of transition-metal complexes. ,− At the photoluminescence level, Ln­(III) complexes can exhibit broad-spectrum emission from the visible to near-infrared region, often resulting in a variety of special properties, including large Stokes shifts, pure monochromatic luminescence, high quantum yield, and long-lived excited state. The aforementioned properties can be further extended to practical applications in several aspects, such as OLEDs, bioprobes, and lasers. − Although the luminescence quantum yield and emission lifetime of lanthanide complexes are susceptible to their coordination environment, they generally exhibit an emission spectrum that is very characteristic and easily distinguishable directly by the naked eye.…”