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Sensitization of NIR luminescence of Yb<sup>3+</sup> by Zn<sup>2+</sup> chromophores in heterometallic complexes with a bridging Schiff-base ligand

DOIFull Paper Access

19

Citations

50

References

2017

Year

Anatoly P. Pushkarev, Tatyana V. Balashova, Andrey A. Kukinov, Maxim V. Arsenyev, Artem N. Yablonskiy, D. I. Kryzhkov, B. A. Andreev, Roman V. Rumyantcev, Georgy K. Fukin, M.N. Bochkarev
Dalton Transactions

Abstract

Herein, complexes [ZnL]<sub>2</sub> (1), {(H<sub>2</sub>O)Zn(μ-L)Yb[OCH(CF<sub>3</sub>)<sub>2</sub>]<sub>3</sub>} (2), {[(CF<sub>3</sub>)<sub>2</sub>HCO]Zn(μ-L)Yb[OCH(CF<sub>3</sub>)<sub>2</sub>](μ-OH)}<sub>2</sub> (3), and [(H<sub>2</sub>O)Ln<sub>2</sub>(L)<sub>3</sub>] (Ln = Yb (4) and Gd (5)) containing a bridging Schiff-base ligand (H<sub>2</sub>L = N,N'-bis(3-methoxy salicylidene)phenylene-1,2-diamine) were synthesized. The compounds 1-4 were structurally characterized. The ytterbium derivatives 2-4 exhibited bright NIR metal-centred photoluminescence (PL) of Yb<sup>3+</sup> ion under one- (λ<sub>ex</sub> = 380 nm) and two-photon (λ<sub>ex</sub> = 750 nm) excitation. The superior luminescence properties of complex 2, which was suggested as a marker for NIR bioimaging, were explained via the strong absorption of the 375 nm LMCT state of the ZnL chromophore, efficient energy transfer from ZnL towards Yb<sup>3+</sup> through a reversible ligand-to-lanthanide electron transfer process, and absence of luminescence quenchers (C-H and O-H groups) in the first coordination sphere of the rare-earth atom.

References

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