Constructing lanthanide [Nd(iii), Er(iii) and Yb(iii)] complexes using a tridentate N,N,O-ligand for near-infrared organic light-emitting diodes

Abstract

A novel type of NIR-emitting lanthanide complexes Ln(PND)3 (Ln = Nd, Er and Yb) was designed and synthesized based on a tridentate monoanionic N,N,O-ligand 6-(pyridin-2-yl)-1,5-naphthyridin-4-ol (PND). Such complex owns definite charge-neutral, coordination-saturated and mononuclear structure that is proved by X-ray single crystal diffraction of Nd(PND)3. Photophysical studies on the ligand and complexes reveal that the PND ligand has suitable energy level to sensitize the near-infrared (NIR) emitting lanthanide ions (Nd(3+), Er(3+), and Yb(3+)). Among the three compounds, Yb(PND)3 shows the highest photoluminescence quantum yield up to 0.9% in a mixture of acetonitrile and methanol solution (10 : 1, v/v, 10(-4) M). Thermal measurements indicate that these compounds have high decomposition (Td) and glass transition (Tg) temperature up to 420 and 265 °C, respectively, implying great advantage for constructing organic electronic devices via vacuum deposition method. At last, NIR organic light-emitting diodes (OLEDs) with simple three-layer structure were fabricated to test their electroluminescent performance, showing maximum NIR irradiance and maximum external quantum efficiency (EQE) of 25 μW cm(-2) and 0.019% for Nd(3+), 0.46 μW cm(-2) and 0.004% for Er(3+), and 86 μW cm(-2) and 0.14% for Yb(3+), respectively.

Review on the Electroluminescence Study of Lanthanide Complexes

“…In 2013, Wei et al introduced pyridine moiety into 1,5‐naphthyridine‐4‐ol to construct a novel neodymium(III) complex Nd‐9 (Scheme ). The triplet energy level of the tridentate ligand is 18 940 cm −1 (2.4 eV), which is higher than the 4 F 3/2 level of Nd 3+ (≈11 500 cm −1 ), indicating efficient energy transfer from ligand to Nd 3+ .…”

“…In 2013, Wei et al obtained Er‐14 (Scheme ) from a novel tridentate ligand which derived from 8‐hydroxyquinoline. The triplet energy level of the ligand was 18 940 cm −1 which is higher than the 4 I 13/2 energy level of Er 3+ (≈6600 cm −1 ).…”

“…In 2013, Wei and co‐workers synthesized complex Yb‐22 (Scheme ). The triplet energy level of the tridentate ligand was 18 940 cm −1 , which was higher than the 5 F 5/2 energy level of Yb 3+ (≈10 000 cm −1 ), indicating that the ligand could efficiently transfer energy to the center Yb 3+ .…”

Synthesis, Characterization and Properties of Novel Coumarin Derivatives and Their Europium Complexes

“…Their fascinating optical properties make the complexes attractive for multiple applications, such as MRI contrast agents [1,2], optical amplifiers [3,4], organic light emitting diodes (OLEDs) [5,6], probes [7,8], lasers [9], etc. The luminescence intensity of rare earth complexes is strongly dependent on the efficiency of ligand absorption in the UV region, the efficiency of ligand-to-metal energy transfer, and the efficiency of rare earth luminescence [10], thus the luminescence intensity of rare earth complexes is relationship to central ion and the structure of organic ligand.…”

Mass spectrometry of lanthanide(III) complexes with 2,6‐diformylpyridine bis(4‐pyridylcarbohydrazone) and its unusual methylation observed in matrix‐assisted laser desorption/ionization mass spectra

“…[10][11][12][13] Recently, much interest has been paid to the application of lanthanide complexes in light-emitting diodes. [14][15][16][17][18][19][20][21] Hydrazone complexes with ions of rare earth metals have found extensive use in medicine as, for example, contrast agents for imaging [22] or as radiopharmaceuticals. [23] One valuable method to study the interaction between ligands and metal ions is soft ionization mass spectrometry and, in particular, electrospray ionization (ESI) and matrixassisted laser desorption/ionization (MALDI).…”