A comparison of sensitized Ln(<scp>iii</scp>) emission using pyridine- and pyrazine-2,6-dicarboxylates – part II

Moore, Evan G.; Grilj, Jakob; Vauthey, Eric; Ceroni, Paola

doi:10.1039/c2dt32229c

Cited by 22 publications

(17 citation statements)

References 31 publications

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“…A very similar spectro-temporal pattern is observed for solutions of Na 2 DPA (Figure ). In a study on lanthanoide complexes of DPA 2– in acetonitrile, except for the 100 fs component, similar transient spectra and comparable lifetimes have been observed.…”

Section: Resultssupporting

confidence: 52%

Femtosecond Spectroscopy of Calcium Dipicolinate—A Major Component of Bacterial Spores

et al. 2016

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Bacterial spores are rich in calcium dipicolinate (CaDPA). The role of this compound in the high UV resistance of spore DNA and their unique DNA photochemistry is not yet clarified. Here, the photophysical properties of CaDPA dissolved in water are studied by means of steady-state and time-resolved spectroscopy as well as quantum chemistry. Upon 255 nm excitation, a fluorescence emission with a yield of 1.7 × 10(-5) is detected. This low yield is in line with a measured fluorescence lifetime of 110 fs. Transient absorption experiments point to further transitions with time constants of 92 ps and 6.8 μs. The microsecond time constant is assigned to the decay of a triplet state. The yield of this state is close to unity. With the aid of quantum chemistry (TD-DFT, DFT-MRCI), the following transitions are identified. The primarily excited (1)ππ* state depletes within 110 fs. The depletion results in the population of an energetically close lying (1)nπ* state. An El-Sayed allowed intersystem crossing process with a time constant of 92 ps ensues. Implications of these findings on the interaction between photoexcited CaDPA and spore DNA are discussed.

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Section: Resultssupporting

confidence: 52%

Femtosecond Spectroscopy of Calcium Dipicolinate—A Major Component of Bacterial Spores

et al. 2016

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“…To further illustrate the ligand effects on the NIR emission of Yb complexes, the quantum yields of NIR emission were measured by comparative methods12, 14 with YbTPP(Tp) (TPP=5,10,15,20‐tetraphenylporphyrinate, Tp=hydridotris(1‐pyrazolyl)borate) as standard. The estimated error for the quantum yields is ±15 % 14e. The quantum yields of the Yb porpholactones (2.4–4.1 %) are 50–120 % higher than those of the corresponding Yb porphyrins (Table 1).…”

Section: Resultsmentioning

confidence: 85%

Ytterbium(III) Porpholactones: β‐Lactonization of Porphyrin Ligands Enhances Sensitization Efficiency of Lanthanide Near‐Infrared Luminescence

Yang

Cheng

et al. 2014

Chemistry A European J

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The near-infrared (NIR) luminescence efficiency of lanthanide complexes is largely dependent on the electronic and photophysical properties of antenna ligands. Although porphyrin ligands are efficient sensitizers of lanthanide NIR luminescence, non-pyrrolic porphyrin analogues, which have unusual symmetry and electronic states, have been much less studied. In this work, we used porpholactones, a class of β-pyrrolic-modified porphyrins, as ligands and investigated the photophysical properties of lanthanide porpholactones Yb-1 a-5 a. Compared with Yb porphyrin complexes, the porpholactone complexes displayed remarkable enhancement of NIR emission (50-120 %). Estimating the triplet-state levels of porphyrin and porpholactone in Gd complexes revealed that β-lactonization of porphyrinic ligands lowers the ligand T1 state and results in a narrow energy gap between this state and the lowest excited state of Yb(3+) . Transient absorption spectra showed that Yb(III) porpholactone has a longer transient decay lifetime at the Soret band than the porphyrin analogue (30.8 versus 17.0 μs). Thus, the narrower energy gap and longer lifetime arising from β-lactonization are assumed to enhance NIR emission of Yb porpholactones. To demonstrate the potential applications of Yb porpholactone, a water-soluble Yb bioprobe was constructed by conjugating glucose to Yb-1 a. Interestingly, the NIR emission of this Yb porpholactone could be specifically switched on in the presence of glucose oxidase and then switched off by addition of glucose. This is the first demonstration that non-pyrrolic porphyrin ligands enhance the sensitization efficiency of lanthanide luminescence and also display switchable NIR emission in the region of biological analytes (800-1400 nm).

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“…However, to avoid computationally expensive calculations when involving open‐shell 4f metals, we have substituted the Ln III cation with a diamagnetic Y III , which nonetheless has an identical charge and similar ionic radius to the middle Ln III ions 21. We have found this approach to be useful in the past for estimating the geometry and excited‐state energies of metal complexes 22. The resulting optimised geometries are shown in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, Stability and Sensitised Lanthanide Luminescence of Heterobimetallic d/f Terpyridine Complexes

et al. 2014

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The synthesis, solution behavior and photophysical properties of several heteronuclear bimetallic d/f complexes that utilise a Ru II bis-terpyridine moiety as the sensitiser for Eu III , Nd III and Yb III luminescence are reported and compared to a Gd III analogue. The former compounds display sensitised emission in the visible and near-infrared (NIR) regions depending on the choice of the Ln III cation. We illustrate that sensitised lanthanide emission can operate by two distinctly different pathways that involve either the triplet ligand-[a]

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A comparison of sensitized Ln(iii) emission using pyridine- and pyrazine-2,6-dicarboxylates – part II

Cited by 22 publications

References 31 publications

Femtosecond Spectroscopy of Calcium Dipicolinate—A Major Component of Bacterial Spores

Femtosecond Spectroscopy of Calcium Dipicolinate—A Major Component of Bacterial Spores

Ytterbium(III) Porpholactones: β‐Lactonization of Porphyrin Ligands Enhances Sensitization Efficiency of Lanthanide Near‐Infrared Luminescence

Synthesis, Stability and Sensitised Lanthanide Luminescence of Heterobimetallic d/f Terpyridine Complexes

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