Transparent and Hazy Eu_xTb_1–x-Nanopaper with Color-Tuning, Photo-Switching, and White Light-Emitting Properties for Anti-counterfeiting and Light-Softened WLEDs

Abstract

Lanthanide (Ln) metal–organic frameworks (Ln-MOFs) have attracted attention in anti-counterfeiting and white light-emitting diodes (WLEDs) due to their high quantum efficiency, long lifetimes, and characteristic linear spectrum. However, Ln-MOFs have some disadvantages, such as harsh luminescence modulation, low transparency, and poor film formation. In this study, Ln-MOF (Ln = Eu and/or Tb)-modified TEMPO-oxidized cellulose nanofibrils were employed for preparing transparent nanopapers and luminescence modulation. These luminescent nanopapers achieved an excellent light emission color tuning from green, yellow, and red under 365 nm excitation, while 254 nm radiation on these nanopapers only emitted characteristic pink light. Thus, the luminescent nanopapers combined color-tuning and photo-switching properties through the control of Eu3+/Tb3+ molar ratio and excitation wavelength (λEx at 365 and 254 nm), respectively, which greatly improved them for anti-counterfeiting applications. In addition, Ln-MOFs endowed these nanopapers with excellent optical haze (>90%), such that softening of white light from WLEDs was realized in 254 nm-driven UV-LED chips, corresponding white light with good color quality [Commission International de I’Eclairage coordinates, correlated color temperature, and color-rendering index of (0.34, 0.36), 5536 K and 86, respectively].

Lanthanide–Organic Frameworks with Uncoordinated Lewis Base Sites: Tunable Luminescence, Antibiotic Detection, and Anticounterfeiting

“…Crystalline porous metal–organic frameworks (MOFs) have attracted continuous attention in diverse realms, for example, gas selective sorption/separation, − sensing, − catalysis, − magnetism, − proton transport, − etc . Lanthanide-based MOFs (Ln-MOFs), which integrate the merits of large Stokes shifts, high photostability, high quantum yields, long luminescence lifetimes, and excellent luminescence monochromaticity, − are unique luminescence materials for significant applications in tunable luminescence, sensors, information storage, and anticounterfeiting applications. − …”

Near-Infrared Emissive Lanthanide Metal–Organic Frameworks for Targeted Biological Imaging and pH-Controlled Chemotherapy

“…Lanthanide metal–organic frameworks (Ln-MOFs) are a kind of crystalline material structured by self-assembly of trivalent lanthanide series metal ions and organic ligands. , Ln-MOFs possess unique properties that combine the excellent fluorescence properties of lanthanide series metal sites with the intrinsic properties of MOFs, such as high porosity, structural tunability, a modifiable surface, and good biocompatibility. , Ln-MOFs have been considered as novel multifunctional materials in catalysis, gas separation, chemical sensing, bioimaging, and drug delivery. − Originating from the “antenna effect” between trivalent lanthanide ions and ligands, Ln-MOFs exhibit characteristic fluorescence emission with high intensity, high stability, possibly high quantum yield, considerable lifetime, and large Stokes shifts (>150 nm) . Some Ln 3+ ions (Gd 3+ , Eu 3+ , Tb 3+ , Dy 3+ , and Sm 3+ ) have been proven to emit more efficiently in the visible region, and some (Nd 3+ , Yb 3+ , Er 3+ , Ho 3+ , and Tm 3+ ) are more suitable for emitting in the near-infrared region. − It is noted that the research on Ln-MOFs in the visible-light region mainly focuses on Tb-MOFs and Eu-MOFs.…”

“…Therefore, cancer cell growth can be inhibited by inhibiting autophagy. , Chloroquine (CQ) is a well-known potent antimalarial and amebicidal drug widely used and is also a potentially clinical autophagy inhibitor . In recent years, CQ was reported to effectively inhibit the growth and induce apoptosis of cancer cells. , Based on this, the small molecule, CQ, is hereby used in killing cancer cells as the model drug. As a CD44 receptor targeting agent, hyaluronic acid (HA) shows satisfying biocompatibility and biodegradability and can be degraded by the overexpressed hyaluronidase (HAase) in tumor cells, which is chosen to coat on the surface of the drug delivery system in this work …”

“…17,18 Ln-MOFs possess unique properties that combine the excellent fluorescence properties of lanthanide series metal sites with the intrinsic properties of MOFs, such as high porosity, structural tunability, a modifiable surface, and good biocompatibility. 19,20 Ln-MOFs have been considered as novel multifunctional materials in catalysis, gas separation, chemical sensing, bioimaging, and drug delivery. 21−26 Originating from the "antenna effect" between trivalent lanthanide ions and ligands, Ln-MOFs exhibit characteristic fluorescence emission with high intensity, high stability, possibly high quantum yield, considerable lifetime, and large Stokes shifts (>150 nm).…”

Insights into the Effect of Trans-to-Cis Photoisomerization of a Co-coordinated Stilbene Derivative on the Luminescence of Di-β-diketonate Lanthanide Complexes

“…In recent years, smart materials have been studied extensively for their important applications in molecular switches, 1−6 white light-emitting diodes, 7−9 information storage, 10,11 anti-counterfeiting, 12,13 separation and detection, 14−16 drug delivery, 17,18 and other fields. 19−24 Smart material molecules can reversibly change their physical and chemical properties under different external stimuli.…”