Highly NIR-emitting ytterbium complexes containing 2-(tosylaminobenzylidene)-N-benzoylhydrazone anions: structure in solution and use for bioimaging

Current Development of Lanthanide Complexes for Biomedical Applications

Luminescent molecule-based bioimaging system is widely used for precise localization and distinction of cancer/tumor cells. Luminescent lanthanide (Ln(III)) complexes offer long-lived (sub-millisecond time scale) and sharp (FWHM <10 nm) emission, arising from the forbidden 4f-4f electronic transitions. Luminescent Ln(III) complex-based bioimaging has emerged as a promising option for both in vitro and in vivo visualizations. In this mini-review, the historical development and recent significant progress of luminescent Ln(III) probes for bioapplications are introduced. The recent studies are mainly focused on three points: (i) the structural modifications of Ln(III) complexes in both macrocyclic and small ligands, (ii) the acquirement of high resolution luminescence images of cancer/tumor cells and (iii) the constructions of ratiometric biosensors. Furthermore, our recent study is explained as a new Cancer GPS (cancer grade probing for determining tumor grade through photophysical property analyses of intracellular Eu(III) complex.

Recent Progress in Photonic Upconversion Materials for Organic Lanthanide Complexes

Organic lanthanide complexes have garnered significant attention in various fields due to their intriguing energy transfer mechanism, enabling the upconversion (UC) of two or more low-energy photons into high-energy photons. In comparison to lanthanide-doped inorganic nanoparticles, organic UC complexes hold great promise for biological delivery applications due to their advantageous properties of controllable size and composition. This review aims to provide a summary of the fundamental concept and recent developments of organic lanthanide-based UC materials based on different mechanisms. Furthermore, we also detail recent applications in the fields of bioimaging and solar cells. The developments and forthcoming challenges in organic lanthanide-based UC offer readers valuable insights and opportunities to engage in further research endeavors.

Modulating the Inclusive and Coordinating Ability of Thiacalix[4]arene and Its Antenna Effect on Yb3-Luminescence via Upper-Rim Substitution+

The present work introduces the series of thiacalix[4]arenes (H₄L) bearing different upper-rim substituents (R = H, Br, NO₂) for rational design of ligands providing an antenna-effect on the NIR Yb³⁺-centered luminescence of their Yb³⁺ complexes. The unusual inclusive self-assembly of H₃L⁻ (Br) through Br…π interactions is revealed through single-crystal XRD analysis. Thermodynamically favorable formation of dimeric complexes [2Yb³⁺:2HL³⁻] leads to efficient sensitizing of the Yb³⁺ luminescence for H₄L (Br, NO₂), while poor sensitizing is observed for ligand H₄L (H). X-ray analysis of the single crystal separated from the basified DMF solutions of YbCl₃ and H₄L(NO₂) has revealed the transformation of the dimeric complexes into [4Yb³⁺:2L⁴⁻] ones with a cubane-like cluster structure. The luminescence characteristics of the complexes in the solutions reveal the peculiar antenna effect of H₄L(R = NO₂), where the triplet level at 567 nm (17,637 cm⁻¹) arisen from ILCT provides efficient sensitizing of the Yb³⁺ luminescence.

Record efficiency of 1000 nm electroluminescence from a solution-processable host-free OLED

New ytterbium complexes K(Solv)_x[Yb(Lⁿ)₂] (Solv = ethanol and/or water) with 2-tosylaminobenzylidene-aryloylhydrazones (H₂L¹, aryloyl = benzoyl; H₂L², aryloyl = 2-naphthoyl) demonstrated high solubility and hole mobility (ca. 2.6 × 10^-6 cm² V^-1 s^-1), while their electron mobility and PLQY were different. The substitution of a benzoyl substituent with naphthoyl resulted in a significant increase of the electron mobility (6.9 × 10^-7vs. 1.7 × 10^-6 cm² V^-1 s^-1) and a decrease of the quantum yield (1.2% vs. 0.6%). As a result, the optimized OLEDs based on the K[Yb(Lⁿ)₂] layer demonstrated efficiencies up to 385 μW W^-1 and 441 μW W^-1, indicating the superior importance of charge mobility over the quantum yield. These are the highest efficiencies of the Yb electroluminescence.