Symmetry and Rigidity for Boosting Erbium‐Based Molecular Light‐Upconversion in Solution

• Published in: Angewandte Chemie International Edition Vol. 62; no. 50; pp. e202314503 - n/a
• Main Authors: Naseri, Soroush, Taarit, Inès, Bolvin, Hélène, Bünzli, Jean‐Claude, Fürstenberg, Alexandre, Guénée, Laure, Le‐Hoang, Giau, Mirzakhani, Mohsen, Nozary, Homayoun, Rosspeintner, Arnulf, Piguet, Claude
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 11.12.2023; Wiley-VCH Verlag
• Edition: International ed. in English
• Subjects: Adducts; Chemical Sciences; Erbium; Heteroleptic Complexes; Ligands; Molecular Upconversion; Optics; Rigidity; Room temperature; Single Molecule; Upconversion
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202314503

Previously limited to highly symmetrical homoleptic triple‐helical complexes [Er(Lk)3]3+, where Lk are polyaromatic tridentate ligands, single‐center molecular‐based upconversion using linear optics and exploiting the excited‐state absorption mechanism (ESA) greatly benefits from the design of stable and low‐symmetrical [LkEr(hfa)3] heteroleptic adducts (hfa−=hexafluoroacetylacetonate anion). Depending on (i) the extended π‐electron delocalization, (ii) the flexibility and (iii) the heavy atom effect brought by the bound ligand Lk, the near‐infrared (801 nm) to visible green (542 nm) upconversion quantum yield measured for [LkEr(hfa)3] in solution at room temperature can be boosted by up to three orders of magnitude. Moving from homoleptic triple helical erbium complexes to heteroleptic adducts boosts the quantum yield of near‐infrared to visible molecular‐based light‐upconversion by three orders of magnitude in solution at room temperature.