Lanthanide Clusters with Chalcogen Encapsulated Ln: NIR Emission from Nanoscale NdSe_x

Abstract

Ln(SePh) 3 (Ln ) Ce, Pr, Nd) reacts with elemental Se in the presence of Na ions to give (py) 16 Ln 17 NaSe 18 (SePh) 16 , a spherical cluster with a 1 nm diameter. All three rare-earth metals form isostructural products. The molecular structure contains a central Ln ion surrounded by eight five-coordinate Se 2that are then surrounded by a group of 16 Ln that define the cluster surface, with additional µ 3 and µ 5 Se 2-, µ 3 and µ 4 SePh -, and pyridine donors saturating the vacant coordination sites of the surface Ln, and a Na ion coordinating to selenolates, a selenido, and pyridine ligands. NIR emission studies of the Nd compound reveal that this material has a 35% quantum efficiency, with four transitions from the excited state 4 F 3/2 ion to 4 I 9/2 , 4 I 11/2 , 4 I 13/2 , and 4 I 15/2 states clearly evident. The presence of Na + is key to the formation of these larger clusters, where reactions using identical concentrations of Nd(SePh) 3 and Se with either Li or K led only to the isolation of (py) 8 Nd 8 Se 6 (SePh) 12 .

Rare‐Earth Metal Oxo/Hydroxo Clusters – Synthesis, Structures, and Applications

“…[6] In addition, their optical properties have been exploited for use in luminescent materials. [7][8][9] Furthermore, rare-earth metal clusters have been applied in catalytic processes or as precursors for lanthanide-based oxide materials. [10,11] The term "cluster" was originally used for the description of compounds containing several metals connected by metal-to-metal bonds.…”

Beyond 1000 nm Emission Wavelength: Recent Advances in Organic and Inorganic Emitters for Deep‐Tissue Molecular Imaging

“…Except the visible/NIR‐I upconversion emission, RENPs also possess highly efficient downconversion NIR‐II emission . Thanks to the 14 rare‐earth elements which furnish diverse energy level transitions, thus an extended scope of emission profiles can be achieved by changing diverse doping ions . Their advantages in various emission wavelength, elongated lifetime of luminescence, nonphoto bleaching activity, and high biocompatibility have been tapped for biomedical imaging over these years .…”

“…Their advantages in various emission wavelength, elongated lifetime of luminescence, nonphoto bleaching activity, and high biocompatibility have been tapped for biomedical imaging over these years . RENPs used for the potential of fluorescence imaging in the NIR‐II were exploited in recent decades …”

“…Molecular NIR‐II emitters without D–A–D scaffold have also been highlighted and enriched the library of NIR‐II dyes (Figure b). Interestingly, recent some high quantum yield of NIR‐I fluorophores such as ICG (Em max : 822 nm), IRDye 800 (Em max : 789 nm), and IR‐12N3 (Em max : 800 nm) with long NIR‐II emission tails extending beyond 1500 nm have been highlighted for bioimaging applications such as observing brain vessels and lymphatic nodes by off‐peak NIR‐II fluorescence detection and their brightness indeed produced comparable brightness levels to the early‐generation D–A–D dyes 27c,47. For example, IRDye800CW displayed 3.8‐fold higher brightness compared to CH1050 between 1000 and 1300 nm 27c,47.…”

“…Interestingly, recent some high quantum yield of NIR‐I fluorophores such as ICG (Em max : 822 nm), IRDye 800 (Em max : 789 nm), and IR‐12N3 (Em max : 800 nm) with long NIR‐II emission tails extending beyond 1500 nm have been highlighted for bioimaging applications such as observing brain vessels and lymphatic nodes by off‐peak NIR‐II fluorescence detection and their brightness indeed produced comparable brightness levels to the early‐generation D–A–D dyes 27c,47. For example, IRDye800CW displayed 3.8‐fold higher brightness compared to CH1050 between 1000 and 1300 nm 27c,47. To further accelerating the clinical use of new NIR‐II imaging technique, the utilization of FDA‐approved ICG also has been extend to bioimaging at >1300 nm in the NIR‐II channel with increased brain vasculature contrast by about 1.4‐fold versus the traditional NIR‐I channel 27c,47.…”