Modified pyridine-2,6-dicarboxylate acid ligands for sensitization of near-infrared luminescence from lanthanide ions (Ln3+ = Pr3+, Nd3+, Gd3+, Dy3+, Er3+)

Abstract

A detailed study of the ability of pyridine-2,6-dicarboxylic acid (1) and its 4-mono-and 3,4,5-trisubstituted analogues to sensitize emission from Pr 3+ , Nd 3+ , Gd 3+ , Dy 3+ and Er 3+ is presented. Sensitization of Ln 3+ emission was demonstrated via the ligands in all complexes, excluding Gd 3+ , with emission covering the spectral range from 500 nm to 1850 nm obtained with variation of the Ln 3+ ion. From the study of the ligand-based photoluminescence obtained from Gd 3+ -complexes, and the relative ligand and Ln 3+ emission obtained from the other complexes, the singlet and triplet state energies of complexes of (1) are estimated to be at 3.1 eV and 2.6 eV respectively whilst for the 3,5-dibromo-substituted complexes (4) they are at 2.9 eV and 2.3 eV. Hypersensitivity of the Er 3+ 4 I15/2 → 2 H11/2 and 4 I15/2 → 4 G11/2 intraatomic transitions is also observed in the 4-chloro-substituted (3) complex. Enhanced sensitization of Nd 3+ (ca. 5-fold) and Er 3+ (ca. 2-fold) near-infrared emission is demonstrated for complexes of (3) and ( 4) respectively in comparison with those of (1).

Features of Luminescent Properties of Alginate Aerogels with Rare Earth Elements as Photoactive Cross-Linking Agents

“…The prospect of using rare earth elements (REE) in the creation of luminophores for analytical purposes, in particular for sensors, is usually associated not only with high quantum yields, long luminescence lifetimes, and a wide spectral range (from UV to IR), in which narrow-band luminescence of REE compounds is observed [ 1 ], but is determined by the possibility of regulating the functional characteristics of such systems when organic ligands of different natures are introduced (usually, the introduction of several ligands out of 4–6 possible options is conformationally acceptable) with the formation of specific photoactive centers “REE ion–ligands” [ 2 , 3 , 4 ]. Moreover, ligands also act as “antennas” [ 5 , 6 , 7 ] for radiation-initiating luminescence. This is even more important because of the low intensity of the luminescence of rare earth ions, caused by the forbidden electronic parity transitions [ 8 ].…”

Synthesis, Structure and Near Infrared Fluorescence Property of a New Nd-MOF Based on a Triangular Benzylamine Ligand

“…So near-infrared uorescence Ln-MOFs may be a much better candidate for the application in biological detection [12,13], biological imaging [14] and barcoding [15]. However, the near-infrared emission signals of Ln-MOFs are easily quenched due to nonradiative relaxation when there are N-H, O-H, and C-H oscil lators on ligands and coordinated solvents which are located close to lanthanide ions [16,17]. So, it's di cult to obtain a NIR uorescence Ln-MOFs with much strong luminescence intensity.…”

Blue-LED-excitable NIR-II luminescent lanthanide-doped SrS nanoprobes for ratiometric thermal sensing

“…To circumvent the limitation of Ln 3+ -doped NIR-II luminescent NCs, it is of fundamental importance to introduce an antenna that can effectively harvest the excitation light and sensitize the NIR-II luminescence of Ln 3+ emitters [30][31][32][33]. In this regard, optical entities of allowed transitions with large absorption cross-sections such as Ce 3+ , Bi 3+ , ligand-to-metal charge transfer states, and the host absorption of semiconductors can be effective sensitizers for Ln 3+ luminescence [34][35][36][37].…”