Rare-earth coordination polymers with multimodal luminescence on the nano-, micro-, and milli-second time scales

Abstract

Summary We present a coordination polymer based on rare-earth metal centers and carboxylated 4,4′-diphenyl-2,2′-bipyridine ligands. We investigate Y 3+ , Lu 3+ , Eu 3+ , and a statistical mixture of Y 3+ with Eu 3+ as metal centers. When Y 3+ or Lu 3+ is exclusively present in the coordination polymer, biluminescence from the ligand is observed: violet emission from the singlet state (417 nm, 0.9 ns lifetime) and orange emission from the triplet state (585 nm, 76 ms (Y 3+ ) and 31 ms (Lu 3+ )). When Eu 3+ is present in a statistical mixture with Y 3+ , red emission from the Eu 3+ (611 nm, ) is observed in addition to the ligand emissions. We demonstrate that this multi-mode emission is enabled by the immobility of singlet and triplet states on the ligand. Eu 3+ only receives energy from adjacent ligands. Meanwhile, in the broad inhomogeneous distribution of ligand energies, higher energy states favor singlet emission, whereas faster intersystem crossing in the more stabilized ligands enhances their contribution to triplet emission.

Air‐Stable Solid‐State Photoluminescence Standards for Quantitative Measurements Based on 4′‐Phenyl‐2,2′ : 6′,2′′‐Terpyridine Complexes with Trivalent Lanthanides

“…For their Tb 3+ analogues, they are 28.9(5) %/0.7077(6) ms for 2‐Tb and 23.0(4) %/0.4122(5) ms for 3‐Tb , noticeably lower than for 1‐Tb . The observed lifetimes and quantum yields of the complexes obtained are well comparable to trivalent europium and terbium coordination compounds with efficient sensitiser ligands, [57,72–76] especially with 2,2′ : 6′,2“‐terpyridine derivatives [50,52,55,67] . Simultaneous thermal analyses of 2‐Ln and 3‐Ln are presented in the SI (Figures S17‐S20).…”

Tuning the Red-to-Green-Upconversion Luminescence Intensity Ratio of Na3ScF6: 20% Yb3+, 2% Er3+ Particles by Changes in Size

“…Lanthanide-doped nanomaterials enable the conversion from near-infrared light to visible light due to the anti-Stokes effect when two or more low-energy photons are sequentially absorbed and higher-energy photons are emitted [ 1 , 2 , 3 , 4 ]. These nanomaterials have the advantages of long luminescence lifetimes, narrow emission bands, high penetration abilities and chemical stability, making them suitable for potential applications in bioimaging, infrared photothermal therapy, fluorescent biomarkers, anti-counterfeiting, photocatalysis, photodetectors, optoelectronic devices, sensors and other fields [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. In particular, red-upconversion-luminescence nanomaterials can be better suited to biological applications.…”