Near-Infrared and Visible Luminescence from Terphenyl-Based Lanthanide(III) Complexes Bearing Amido and Sulfonamido Pendant Arms

Abstract

A series of m‐terphenyl‐based ligands bearing three coordinating oxyacetate and two amido or two sulfonamido groups, (1a‐b)H3 and (2)H3, respectively, have been synthesized and characterized. The structures of the corresponding neutral complexes have been studied using 1H‐NMR spectroscopy and luminescence experiments. The photophysical properties of the (1a‐b)Eu, (2)Eu, (1a)Tb, and (2)Tb complexes have been studied to determine the structure of the first coordination sphere in methanol. The first coordination sphere consists of eight donor atoms provided by the ligand (three chelating oxyacetate groups and two amide or sulfonamide oxygens), and one methanol molecule. The (1a)Dy and (1a)Sm complexes exhibited sensitized luminescence in the visible spectral region, but the luminescence intensity was very sensitive to quenching by C‐H groups. The near‐infrared emitting (1a)Ln and (2)Ln complexes exhibited sensitized luminescence at wavelengths (at 880, 1060, and 1330 nm for Nd3+, at 980 nm for Yb3+, and at 1550 nm for Er3+) of interest for applications in optical telecommunication devices. The luminescence lifetimes of these complexes in DMSO and [D6]DMSO are in the range of microseconds. The luminescent state of the NIR emitting lanthanide ions is very efficiently quenched by high frequency oscillators (such as C‐H groups) in the solvent and the ligand.

Lanthanide Complexes for Luminescence Imaging Applications

“…The authors suggest that low quantum yields are obtained due to transferred energy being lost via vibronic coupling of the lanthanide excited state with C -H oscillators in the solvent and within the ligand framework. Related terphenyl ligands incorporating sulphonamido (3a) and amide (3b) groups have also been reported providing at least eight donor atoms for metal ion chelation (58). Laser excitation at 350 nm again resulted in metal-based luminescence demonstrating that like europium(III) and terbium(III), neodymium(III), ytterbium(III), and erbium(III) can also accept energy from high lying ligand centred triplet states (in this case the terphenyl based triplet state is ca.…”

Increased Luminescent Lifetimes of Ln3+ Complexes Emitting in the Near-Infrared as a Result of Deuteration

“…[9] The ligand ( Figure 1) has advantages in terms of solubility, shielding of the ion to solvent molecules, and easy functionalization with chromophores and dyes. [8,12Ϫ14] …”

“…[8,9] Even with effective shielding of the ion from the solvent the lifetimes remain low relative to those in inorganic materials. [10] One strategy to increase the quantum yield of the lanthanide ions is to eliminate the CϪH oscillators in close proximity to the lanthanide ion by introduction of deuterium or fluorine in place of hydrogen.…”

The Influence of Synthesis Parameters on Particle Size and Photoluminescence Characteristics of Ligand Capped Tb3+:LaF3

“…Optically-active polymer nanocomposites are suitable materials for use in a series of optoelectronic applications due to their low cost and ease of processing [1,2]. Amorphous polymers such as polymethyl methacrylate (PMMA) are utilized in numerous optical applications because they are highly transparent in the visible.…”