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Vibrational Quenching in Near‐Infrared Emitting Lanthanide Complexes: A Quantitative Experimental Study and Novel Insights
Author(s) -
Mara Dimitrije,
Artizzu Flavia,
Smet Philippe F.,
Kaczmarek Anna M.,
Van Hecke Kristof,
Van Deun Rik
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201904320
Subject(s) - lanthanide , triphenylphosphine oxide , molecule , quenching (fluorescence) , chemistry , coordination sphere , ligand (biochemistry) , integrating sphere , fluorescence , crystallography , photochemistry , triphenylphosphine , ion , organic chemistry , catalysis , biochemistry , physics , receptor , quantum mechanics , optics
Two series of novel NIR‐emissive complexes of Nd 3+ , Sm 3+ , Er 3+ and Yb 3+ with two different β‐diketonate ligands (L 1 =4,4,4‐trifluoro‐1‐phenyl‐1,3‐butadione and L 2 =4,4,4‐trifluoro‐1‐(4‐chlorophenyl)‐1,3‐butadione) are reported. The neutral triphenylphosphine oxide (tppo) ligand was used to replace coordinated water molecules in the first coordination sphere of the as‐obtained [Ln(L 1(2) ) 3 (H 2 O) 2 ] complexes to afford water‐free [Ln(L 1(2) ) 3 (tppo) 2 ] molecular species. Upon replacement of water molecules by tppo units, the NIR emission lifetimes of the Nd 3+ , Er 3+ and Sm 3+ complexes increase by about one order of magnitude up to values of ≈9, 8 and 113 ms while Yb 3+ complexes reach intrinsic quantum yields as high as to Φ Yb =6.5 %., which are remarkably high for fully hydrogenated complexes. Vibrational quenching by CH and OH oscillators has been quantitatively assessed by implementing the Förster's model of resonance energy transfer on the basis of experimental data. This study demonstrates that highly efficient NIR‐emitting lanthanide complexes can be obtained with facile, cheap and accessible syntheses through a rational design.