Lanthanide-Doped Luminescent Nanophosphors via Ionic Liquids

Abstract

Lanthanide (Ln3+) ion(s)-doped or rare-earth ion(s)-doped nanomaterials have been considered a very important class of nanophosphors for various photonic and biophotonic applications. Unlike semiconductors and organic-based luminescent particles, the optical properties of Ln3+-doped nanophosphors are independent of the size of the nanoparticles. However, by varying the crystal phase, morphology, and lattice strain of the host materials along with making core-shell structure, the relaxation dynamics of dopant Ln3+ ions can be effectively tuned. Interestingly, a judicious choice of dopant ions leads to unparallel photophysical dynamics, such as quantum cutting, upconversion, and energy transfer. Recently, ionic liquids (ILs) have drawn tremendous attention in the field of nanomaterials synthesis due to their unique properties like negligible vapor pressure, nonflammability, and, most importantly, tunability; thus, they are often called “green” and “designer” solvents. This review article provides a critical overview of the latest developments in the ILs-assisted synthesis of rare-earth-doped nanomaterials and their subsequent photonic/biophotonic applications, such as energy-efficient lighting and solar cell applications, photodynamic therapy, and in vivo and in vitro bioimaging. This article will emphasize how luminescence dynamics of dopant rare-earth ions can be tuned by changing the basic properties of the host materials like crystal phase, morphology, and lattice strain, which can be eventually tuned by various properties of ILs such as cation/anion combination, alkyl chain length, and viscosity. Last but not least, different aspects of ILs like their ability to act as templating agents, solvents, and reaction partners and sometimes their “three-in-one” use in nanomaterials synthesis are highlighted along with various photoluminescence mechanisms of Ln3+ ion like up- and downconversion (UC and DC).

Multifunctional Lanthanide-Doped Binary Fluorides and Graphene Oxide Nanocomposites Via a Task-Specific Ionic Liquid

“…On the other hand, the cationic part (imidazolium, pyridinium, ammonium, ions, etc.) participates in the capping/templating agent. − For example, Zheng et al have shown that the [Emim] + ions can serve as capping agents based on their strong interactions with the (110) facets of rutile, and the [Emim]Br favors the formation of the rutile structure with a rod-like shape due to the mutual π-stacking interactions of imidazole rings . It has been experimentally as well as theoretically proven that the cationic moiety of an IL is self-assembled about the nucleation site during the growth of nanoparticles.…”

Lanthanide (Eu, Tb, La)-Doped ZnO Nanoparticles Synthesized Using Whey as an Eco-Friendly Chelating Agent

“…Additionally, according to the electric dipole selection rule, the 5 D 0 → 7 F 0 transition is only allowed for the following 10 site symmetries, C s , C 1 , C n , and C nv (n = 2, 3, 4, 6) [60,61]. Therefore, the only point groups without an inversion center and showing one band for the 5 D 0 → 7 F 0 transition, two bands for the 5 D 0 → 7 F 1 transition and three bands for the 5 D 0 → 7 F 2 transition are C 3 and C 3v .…”

Nanoengineering of Lanthanide‐Doped BaGdF5‐Graphene Oxide as a Tunable‐Nanocomposite Platform for Biological Applications

“…[6,7,[22][23][24][25] Lately, various GObased nanocomposites materials (NCM) like TiO 2 -graphene nanocomposite, ZnO nanorods/graphene, graphene nanosheet/ Al 2 O 3 , graphene/europium oxide (Eu 2 O 3 ), metal-organic framework (MOFs) composites have been synthesized, which finds huge application in the field of magnetic, lighting, photocatalysis/catalysis, solar cell etc. [7,19,[26][27][28][29][30][31][32] Interestingly, even though the Ln 3 + doped nanoparticles have superior optical and magnetic properties than semiconductor nanocrystals and organic fluorophores, [12][13]15,18,[32][33] the nanocomposite between Ln 3 + doped ions in ternary fluoride with GO as host to offer tunable functionalization capabilities are virtually non-existing. Thus, we undertook this study to describe a successful synthesis of two variants of a nanocomposite between Ln 3 + (Eu or Tb)-doped BaGdF 5 nanoparticles and GO as host material using room temperature, taskspecific ionic liquids based one-pot 'green' synthesis approach.…”