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Title: Luminescent lanthanide complexes with a pyridine-bis(carboxamide)-bithiophene sensitizer showing wavelength-dependent singlet oxygen generation
A new pyridine-bis(carboxamide)-based ligand with a bithiophene pendant, 2Tcbx, was synthesized. Its lanthanide ion (Ln III ) complexes, [Ln(2Tcbx) 2 ] 3+ , were isolated and their photophysical properties were explored. Upon excitation at 360 nm, these complexes display emission in the near-infrared (NIR) with efficiencies of 0.69% for Ln III = Yb III , 0.20% for Ln III = Nd III , and 0.01% for Ln III = Er III , respectively. Concurrent 1 O 2 formation was seen for all complexes, with efficiencies of 19% for the Yb III complex, 25% for the Nd III complex, and 9% for the Er III complex. When exciting at a longer wavelength, 435 nm, only Ln III emission was observed and larger efficiencies of Ln III -centered emission were obtained. The lack of 1 O 2 generation indicates that energy pathways involving different ligand conformations, which were investigated by transient absorption spectroscopy, are involved in the sensitization process, and enable the wavelength-dependent generation of 1 O 2 . more »« less
Monteiro, Jorge H.; Hiti, Ethan A.; Hardy, Emily E.; Wilkinson, Grant R.; Gorden, John D.; Gorden, Anne E.; de Bettencourt-Dias, Ana
(, Chemical Communications)
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(Ed.)
A new naphthylsalophen and its 3 : 2 ligand-to-lanthanide sandwich-type complexes were isolated. When excited at 380 nm, the complexes display the characteristic metal-centred emission for Nd III , Er III and Yb III . Upon 980 nm excitation, in mixed lanthanide and the Er complexes, Er-centred upconversion emission at 543 and 656 nm is observed, with power densities as low as 2.18 W cm −2 .
Nguyen, Tu N.; Eliseeva, Svetlana V.; Chow, Chun Y.; Kampf, Jeff W.; Petoud, Stéphane; Pecoraro, Vincent L.
(, Inorganic Chemistry Frontiers)
A new series of gallium( iii )/lanthanide( iii ) metallacrown (MC) complexes ( Ln-1 ) was synthesized by the direct reaction of salicylhydroxamic acid (H 3 shi) with Ga III and Ln III nitrates in a CH 3 OH/pyridine mixture. X-ray single crystal analysis revealed two types of structures depending on whether the nitrate counterion coordinate or not to the Ln III : [LnGa 4 (shi) 4 (H 2 shi) 2 (py) 4 (NO 3 )](py) 2 (Ln = Gd III , Tb III , Dy III , Ho III ) and [LnGa 4 (shi) 4 (H 2 shi) 2 (py) 5 ](NO 3 )(py) (Ln = Er III , Tm III , Yb III ). The representative Tb-1 and Yb-1 MCs consist of a Tb/YbGa 4 core with four [Ga III –N–O] repeating units forming a non-planar ring that coordinates the central Ln III through the oxygen atoms of the four shi 3− groups. Two H 2 shi − groups bridge the Ln III to the Ga III ring ions. The Yb III in Yb-1 is eight-coordinated while the ligation of the nine-coordinated Tb III in Tb-1 is completed by one chelating nitrate ion. Ln-1 complexes in the solid state showed characteristic sharp f–f transitions in the visible (Tb, Dy) and near-infrared (Dy, Ho, Er, Yb) spectral ranges upon excitation into the ligand-centered electronic levels at 350 nm. Observed luminescence lifetimes and absolute quantum yields were collected and discussed. For Yb-1 , luminescence data were also acquired in CH 3 OH and CD 3 OD solutions and a more extensive analysis of photophysical properties was performed. This work demonstrates that while obtaining highly luminescent lanthanide( iii ) MCs via a direct synthesis is feasible, many factors such as molar absorptivities, triplet state energies, non-radiative deactivations through vibronic coupling with overtones of O–H, N–H, and C–H oscillators and crystal packing will strongly contribute to the luminescent properties and should be carefully considered.
Eliseeva, Svetlana V.; Nguyen, Tu N.; Kampf, Jeff W.; Trivedi, Evan R.; Pecoraro, Vincent L.; Petoud, Stéphane
(, Chemical Science)
A family of Zn 16 Ln(HA) 16 metallacrowns (MCs; Ln = Yb III , Er III , and Nd III ; HA = picoline- (picHA 2− ), pyrazine- (pyzHA 2− ), and quinaldine- (quinHA 2− ) hydroximates) with an ‘encapsulated sandwich’ structure possesses outstanding luminescence properties in the near-infrared (NIR) and suitability for cell imaging. Here, to decipher which parameters affect their functional and photophysical properties and how the nature of the hydroximate ligands can allow their fine tuning, we have completed this Zn 16 Ln(HA) 16 family by synthesizing MCs with two new ligands, naphthyridine- (napHA 2− ) and quinoxaline- (quinoHA 2− ) hydroximates. Zn 16 Ln(napHA) 16 and Zn 16 Ln(quinoHA) 16 exhibit absorption bands extended into the visible range and efficiently sensitize the NIR emissions of Yb III , Er III , and Nd III upon excitation up to 630 nm. The energies of the lowest singlet (S 1 ), triplet (T 1 ) and intra-ligand charge transfer (ILCT) states have been determined. Ln III -centered total ( Q LLn) and intrinsic ( Q LnLn) quantum yields, sensitization efficiencies ( η sens ), observed ( τ obs ) and radiative ( τ rad ) luminescence lifetimes have been recorded and analyzed in the solid state and in CH 3 OH and CD 3 OD solutions for all Zn 16 Ln(HA) 16 . We found that, within the Zn 16 Ln(HA) 16 family, τ rad values are not constant for a particular Ln III . The close in energy positions of T 1 and ILCT states in Zn 16 Ln(picHA) 16 and Zn 16 Ln(quinHA) 16 are preferred for the sensitization of Ln III NIR emission and η sens values reach 100% for Nd III . Finally, the highest values of Q LLn are observed for Zn 16 Ln(quinHA) 16 in the solid state or in CD 3 OD solutions. With these data at hand, we are now capable of creating MCs with desired properties suitable for NIR optical imaging.
Abstract Multiplex imaging in the second near‐infrared window (NIR‐II, 1000–1700 nm) provides exciting opportunities for more precise understanding of biological processes and more accurate diagnosis of diseases by enabling real‐time acquisition of images with improved contrast and spatial resolution in deeper tissues. Today, the number of imaging agents suitable for this modality remains very scarce. In this work, we have synthesized and fully characterized, including theoretical calculations, a series of dimeric LnIII/GaIIImetallacrowns bearing RuIIpolypyridyl complexes,LnRu‐3(Ln=YIII, YbIII, NdIII, ErIII). Relaxed structures ofYRu‐3in the ground and the excited electronic states have been calculated using dispersion‐corrected density functional theory methods. Detailed photophysical studies ofLnRu‐3have demonstrated that characteristic emission signals of YbIII, NdIIIand ErIIIin the NIR‐II range can be sensitized upon excitation in the visible range through RuII‐centered metal‐to‐ligand charge transfer (MLCT) states. We have also showed that these NIR‐II signals are unambiguously detected in an imaging experiment using capillaries and biological tissue‐mimicking phantoms. This work opens unprecedented perspectives for NIR‐II multiplex imaging using LnIII‐based molecular compounds.
Kotyk, Christopher M.; Weber, Jeremy E.; Hyre, Ariel S.; McNeely, James; Monteiro, Jorge H.; Domin, Marek; Balaich, Gary J.; Rheingold, Arnold L.; de Bettencourt-Dias, Ana; Doerrer, Linda H.
(, Inorganic Chemistry)
Four groups of rare-earth complexes, comprising 11 new compounds, with fluorinated O-donor ligands ([K(THF)6][Ln(OC4F9)4(THF)2] (1-Ln; Ln = Ce, Nd), [K](THF)x[Ln(OC4F9)4(THF)y] (2-Ln; Ln = Eu, Gd, Dy), [K(THF)2][Ln(pinF)2(THF)3] (3-Ln; Ln = Ce, Nd), and [K(THF)2][Ln(pinF)2(THF)2] (4-Ln; Ln = Eu, Gd, Dy, Y) have been synthesized and characterized. Single-crystal X-ray diffraction data were collected for all compounds except 2-Ln. Species 1-Ln, 3-Ln, and 4-Ln are uncommon examples of six-coordinate (Eu, Gd, Dy, and Y) and seven-coordinate (Ce and Nd) LnIII centers in all-O-donor environments. Species 1-Ln, 2-Ln, 3-Ln, and 4-Ln are all luminescent (except where Ln = Gd and Y), with the solid-state emission of 1-Ce being exceptionally blue-shifted for a Ce complex. The emission spectra of the six Nd, Eu, and Dy complexes do not show large differences based on the ligand and are generally consistent with the well-known free-ion spectra. Time-dependent density functional theory results show that 1-Ce and 3-Ce undergo allowed 5f → 4d excitations, consistent with luminescence lifetime measurements in the nanosecond range. Eu-containing 2-Eu and 4-Eu, however, were found to have luminescence lifetimes in the millisecond range, indicating phosphorescence rather than fluorescence. The performance of a pair of multireference models for prediction of the Ln = Nd, Eu, and Dy absorption spectra was assessed. It was found that spectroscopy-oriented configuration interaction as applied to a simplified model in which the free-ion lanthanide was embedded in ligand-centered Löwdin point charges performed as well (Nd) or better (Eu and Dy) than canonical NEVPT2 calculations, when the ligand orbitals were included in the treatment.
Johnson, Katherine R., Vittardi, Sebastian B., Gracia-Nava, Manuel A., Rack, Jeffrey J., and de Bettencourt-Dias, Ana. Luminescent lanthanide complexes with a pyridine-bis(carboxamide)-bithiophene sensitizer showing wavelength-dependent singlet oxygen generation. Retrieved from https://par.nsf.gov/biblio/10188550. Dalton Transactions 49.20 Web. doi:10.1039/d0dt01034k.
Johnson, Katherine R., Vittardi, Sebastian B., Gracia-Nava, Manuel A., Rack, Jeffrey J., & de Bettencourt-Dias, Ana. Luminescent lanthanide complexes with a pyridine-bis(carboxamide)-bithiophene sensitizer showing wavelength-dependent singlet oxygen generation. Dalton Transactions, 49 (20). Retrieved from https://par.nsf.gov/biblio/10188550. https://doi.org/10.1039/d0dt01034k
Johnson, Katherine R., Vittardi, Sebastian B., Gracia-Nava, Manuel A., Rack, Jeffrey J., and de Bettencourt-Dias, Ana.
"Luminescent lanthanide complexes with a pyridine-bis(carboxamide)-bithiophene sensitizer showing wavelength-dependent singlet oxygen generation". Dalton Transactions 49 (20). Country unknown/Code not available. https://doi.org/10.1039/d0dt01034k.https://par.nsf.gov/biblio/10188550.
@article{osti_10188550,
place = {Country unknown/Code not available},
title = {Luminescent lanthanide complexes with a pyridine-bis(carboxamide)-bithiophene sensitizer showing wavelength-dependent singlet oxygen generation},
url = {https://par.nsf.gov/biblio/10188550},
DOI = {10.1039/d0dt01034k},
abstractNote = {A new pyridine-bis(carboxamide)-based ligand with a bithiophene pendant, 2Tcbx, was synthesized. Its lanthanide ion (Ln III ) complexes, [Ln(2Tcbx) 2 ] 3+ , were isolated and their photophysical properties were explored. Upon excitation at 360 nm, these complexes display emission in the near-infrared (NIR) with efficiencies of 0.69% for Ln III = Yb III , 0.20% for Ln III = Nd III , and 0.01% for Ln III = Er III , respectively. Concurrent 1 O 2 formation was seen for all complexes, with efficiencies of 19% for the Yb III complex, 25% for the Nd III complex, and 9% for the Er III complex. When exciting at a longer wavelength, 435 nm, only Ln III emission was observed and larger efficiencies of Ln III -centered emission were obtained. The lack of 1 O 2 generation indicates that energy pathways involving different ligand conformations, which were investigated by transient absorption spectroscopy, are involved in the sensitization process, and enable the wavelength-dependent generation of 1 O 2 .},
journal = {Dalton Transactions},
volume = {49},
number = {20},
author = {Johnson, Katherine R. and Vittardi, Sebastian B. and Gracia-Nava, Manuel A. and Rack, Jeffrey J. and de Bettencourt-Dias, Ana},
}
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