Upconversion in molecular hetero-nonanuclear lanthanide complexes in solution

Knighton, Richard C.; Soro, Lohona K.; Lecointre, Alexandre; Pilet, Guillaume; Fateeva, Alexandra; Pontille, Laurie; Francés‐Soriano, Laura; Hildebrandt, Niko; Charbonnière, Loı̈c J.

doi:10.1039/d0cc07337g

Cited by 44 publications

(63 citation statements)

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“…Having significantly improved both accuracy and reliability of the latter technique for measuring weak emitters thanks to the thorough procedures described by Charbonnière and co-workers 21 and by Wurth et al ., 42 c we ultimately found ϕ up tot ([Er(Et-bzimpy) 3 ] 3+ ) = 1.7(2) × 10 −9 and ϕ up tot ([Er(Et-tpy) 3 ] 3+ ) = 5.5(6) × 10 −11 for the upper and lower limits in these erbium complexes ( Table 2 , column 6; preliminary estimations in the 1.6 × 10 −8 and 4.1 × 10 −9 range). 22 As expected for the ESA mechanism ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“… 18 Synthetic chemists, probably unaware of this major physical deadlock, were nonetheless able to overcome this limitation, firstly with the preparation of multi-components supramolecular assemblies exhibiting light-upconversion assigned to the ETU mechanism ( Fig. 3 ), 12,19,20 secondly via the closely related cooperative upconversion (CU) mechanism 21 and finally according to the basic excited state absorption pathway (ESA, Fig. 1 ).…”

Section: Introductionmentioning

confidence: 99%

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Molecular light-upconversion: we have had a problem! When excited state absorption (ESA) overcomes energy transfer upconversion (ETU) in Cr(iii)/Er(iii) complexes

et al. 2021

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Molecular light-upconversion: we have had a problem! When excited state absorption (ESA) overcomes energy transfer upconversion (ETU) in Cr(iii)/Er(iii) complexes

et al. 2021

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“…Considering our previous findings on the cooperative sensitization of Tb by Yb complexes [11,12], we anticipated that a Yb complex formed by complexation with the heptadentate ligand L (Scheme 1) [28] might offer opportunities to observe UC in D 2 O solutions. The spectroscopic properties of the YbL complex were studied in detail together with the interactions of the complex with Tb cations and were shown to allow the formation of heteropolynuclear Yb/Tb complexes that exhibit UC in D 2 O.…”

Section: Methodsmentioning

confidence: 99%

“…Although it is mostly observed in the solid state [6][7][8], examples at the molecular scale in solutions [9][10][11][12] are flourishing thanks to the wide use of lanthanides, with their unique luminescence properties such as long luminescent lifetimes and line-like emission spectra [13,14]. The molecular strategy opens the door to new perspectives in biological applications, considering that it might resolve the drawbacks due to the biotoxicity and hazardous reproducibility of nanomaterials [15].…”

Section: Introductionmentioning

confidence: 99%

“…Thanks to its unique 2 F 5/2 → 2 F 7/2 electronic transition at 980 nm, Yb(III) is the most common sensitizer used, and it allows for reaching the excited state of numerous other lanthanides such as Eu, Tb, Ho, Er or Tm, all of which can emit in the visible spectrum [11,[23][24][25]. Between those different pairs, the Yb/Tb one introduces a particular mechanism called cooperative sensitization [11,12,26,27]. This mechanism helps to overstep the absence of resonant electronic transition between Yb and Tb, but the efficiency is expected to be weak.…”

Section: Introductionmentioning

confidence: 99%

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Yb to Tb Cooperative Upconversion in Supramolecularly Assembled Complexes in a Solution

et al. 2021

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The podand-type ligand L, based on a tertiary amine substituted by three pyridyl-6-phosphonic acid functions, forms hydrated complexes with Ln3+ cations. The luminescence properties of the YbL complex were studied in D2O as a function of the pD and temperature. In basic conditions, increases in the luminescence quantum yield and the excited state lifetime of the Yb centered emission associated with the 2F5/2 → 2F7/2 transition were observed and attributed to a change in the hydration number from two water molecules in the first coordination sphere of Yb at acidic pH to a single one in basic conditions. Upon the addition of TbCl3 salts to a solution containing the YbL complex in D2O, heteropolynuclear Yb/Tb species formed, and excitation of the Yb at 980 nm resulted in the observation of the typical visible emission of Tb as a result of a cooperative upconversion (UC) photosensitization process. The UC was further evidenced by the quadratic dependence of the UC emission as a function of the laser power density.

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Solution‐State Cooperative Luminescence Upconversion in Molecular Ytterbium Dimers

Soro

Knighton

Avecilla

et al. 2022

Advanced Optical Materials

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anti-Stokes emission, UC is a process of choice for bio-analytical applications, removing spurious signals originating from autofluorescence of the samples and light scattering. Consequently, UC has found many applications such as in microscopy and photodynamic therapy, [2] remote cellular activation, [3] or bioassays. [4,5] However, these processes are typically observed in solid-state materials [6] or nanoparticles, [7] but a seminal example of energy transfer UC (ETU) at the molecular scale was reported by Piguet and co-workers in 2011, which consisted of a triply stranded Cr III -Er III -Cr III helicate. [8,9] In the subsequent years this has been expanded to encompass a range of discrete upconverting systems, operating by excited state absorption (ESA), [10][11][12] energy transfer UC, or cooperative sensitizaton (CS). [15][16][17][18] At the molecular scale, much attention must be paid to minimize quenching due to the increased prevalence of nonradiative de-excitation processes from molecules in solution, primarily through OH, NH, and CH oscillators in the first or second coordination sphere. [20][21][22] This is achieved by using sterically encumbering ligand systems, [23] deuteration of the ligand scaffold, [16] or using perdeuterated solvents. [16,24,25] One key impediment in the development of new molecular UC devices is the typical requirement to prepare heterometallic polyads, as is the case with CS systems comprising two or more Yb III sensitizers around Tb III or Ru II acceptors (Figure 1a). [17,26] This approach, despite its effectiveness, is onerous due to the similar chemical reactivity between lanthanides, [27,28] as is the case for mixed Yb/Tb systems, which constrains the synthetic accessibility. [15,16] Inspired by the pioneering work by Auzel [29] on solid-state materials, [30,31] we reported the first example of solution-state molecular cooperative luminescence (CL) using a Yb 9 cluster. [32] This entails double excitation of two proximate Yb III ions at 980 nm which produces emission from a virtual excited state at 503 nm via a two-photon process (Figure 1b). While it is a key tenet of UC processes that the efficiency of UC is improved using more donor ions, there also remains the possibility of concentration quenching, which has been observed in nanoparticles. [33,34] Furthermore, the two-photon power dependence of the UC observed in homo-nonanuclear Yb 9 clusters supports the accepted mechanism of the requirement of only two proximate Yb III ions. Conclusive confirmation of this dinuclear mechanism can only occur through removal of the extraneous Yb III donors to its fundamental form in a dimeric Yb 2 system (lex parsimoniae). This strategy is not feasible in either Two homometallic ytterbium dimers are prepared and their solution-state photoluminescence and upconversion properties are investigated. Both complexes exhibit two-photon cooperative luminescence upconversion in the visible region (λ em ≈ 510 nm) upon excitation into the near-infrared Yb 2 F 5/2 ← 2 F 7/2 absorption band at 98...

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Upconversion in molecular hetero-nonanuclear lanthanide complexes in solution

Abstract: An unprecedented efficiency of upconversion is observed in a nonanuclear Yb8Tb complex with green emission upon NIR excitation of Yb.

Cited by 44 publications

References 28 publications

Molecular light-upconversion: we have had a problem! When excited state absorption (ESA) overcomes energy transfer upconversion (ETU) in Cr(iii)/Er(iii) complexes

Molecular light-upconversion: we have had a problem! When excited state absorption (ESA) overcomes energy transfer upconversion (ETU) in Cr(iii)/Er(iii) complexes

Yb to Tb Cooperative Upconversion in Supramolecularly Assembled Complexes in a Solution

Solution‐State Cooperative Luminescence Upconversion in Molecular Ytterbium Dimers

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