10 research outputs found

    External Heavy-Atom Effect via Orbital Interactions Revealed by Single-Crystal X‑ray Diffraction

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    Enhanced spin–orbit coupling through external heavy-atom effect (EHE) has been routinely used to induce room-temperature phosphorescence (RTP) for purely organic molecular materials. Therefore, understanding the nature of EHE, i.e., the specific orbital interactions between the external heavy atom and the luminophore, is of essential importance in molecular design. For organic systems, halogens (e.g., Cl, Br, and I) are the most commonly seen heavy atoms serving to realize the EHE-related RTP. In this report, we conduct an investigation on how heavy-atom perturbers and aromatic luminophores interact on the basis of data obtained from crystallography. We synthesized two classes of molecular systems including <i>N</i>-haloalkyl-substituted carbazoles and quinolinium halides, where the luminescent molecules are considered as “base” or “acid” relative to the heavy-atom perturbers, respectively. We propose that electron donation from a π molecular orbital (MO) of the carbazole to the σ* MO of the C–X bond (π/σ*) and n electron donation to a π* MO of the quinolinium moiety (n/π*) are responsible for the EHE (RTP) in the solid state, respectively

    External Heavy-Atom Effect via Orbital Interactions Revealed by Single-Crystal X‑ray Diffraction

    No full text
    Enhanced spin–orbit coupling through external heavy-atom effect (EHE) has been routinely used to induce room-temperature phosphorescence (RTP) for purely organic molecular materials. Therefore, understanding the nature of EHE, i.e., the specific orbital interactions between the external heavy atom and the luminophore, is of essential importance in molecular design. For organic systems, halogens (e.g., Cl, Br, and I) are the most commonly seen heavy atoms serving to realize the EHE-related RTP. In this report, we conduct an investigation on how heavy-atom perturbers and aromatic luminophores interact on the basis of data obtained from crystallography. We synthesized two classes of molecular systems including <i>N</i>-haloalkyl-substituted carbazoles and quinolinium halides, where the luminescent molecules are considered as “base” or “acid” relative to the heavy-atom perturbers, respectively. We propose that electron donation from a π molecular orbital (MO) of the carbazole to the σ* MO of the C–X bond (π/σ*) and n electron donation to a π* MO of the quinolinium moiety (n/π*) are responsible for the EHE (RTP) in the solid state, respectively

    General Design Strategy for Aromatic Ketone-Based Single-Component Dual-Emissive Materials

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    Materials with both fluorescence and room-temperature phosphorescence (RTP) can be useful in the field of optoelectronics. Here we present a general strategy, taking advantage of carbonyl compounds, which have been known to possess efficient intersystem crossing with high triplet state yield, as well as a strongly fluorescent intramolecular charge-transfer (ICT) state, to produce materials with both fluorescence and RTP at the same time, or dual-emission. In the presented model systems, in order to generate a suitable ICT state, Lewis acid binding to aromatic ketone derivatives has been proved to be a viable method. We have selected AlCl<sub>3</sub>, BCl<sub>3</sub>, BF<sub>3</sub>, and GdCl<sub>3</sub> as binding Lewis acids, in that they exhibit sufficiently strong binding affinity toward the aromatic ketone derivatives to afford stable complexes and yet do not possess low-lying electronic transitions vs the ligands. We have successfully observed dual-emission from these designed complexes in polymers, which act to suppress competitive thermal decay at room temperature. One of the complexes is particularly interesting as it is dual-emissive in the crystalline state. Single-crystal XRD reveals that the molecule forms multiple hydrogen bonds with its neighbors in crystals, which may significantly enhance the rigidity of the environment

    Nissl staining and cell counting.

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    <p>Nissl staining of cortex (A1-D2) and hippocampus (A3-D4) in each group are shown at two different magnifications (A1-D1, A3-D3: ×200, A2-D2, A4-D4: ×400). Cell counts per visual field (×400) found in the slides with Nissl staining on 15 and 30 days after CO poisoning (B). The values are means ± SDs. <b><i>*</i></b>P < 0.05 comparing to the NC group; <sup>#</sup>P < 0.05 comparing to the CO group and <sup>$</sup>P < 0.05 comparing to the O<sub>2</sub> group.</p

    The mean serum S100β levels at 0, 60, 65, 90, 120, and 150 min after acute CO poisoning.

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    <p>The values are means ± SDs (n = 8).<b><i><sup>*</sup></i></b> comparison of the serum S100β levels in the HOS group with those in the NC group (<sup>**</sup> indicates P < 0.01). <b><i><sup>#</sup></i></b> comparison of the serum S100β levels in the HOS group with those in the O<sub>2</sub> group (<sup>##</sup> indicates P < 0.01).</p

    Aggregation-Induced Emission from Fluorophore–Quencher Dyads with Long-Lived Luminescence

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    Aggregation-induced emission (AIE) is an important photophysical phenomenon in molecular materials and has found broad applications in optoelectronics, bioimaging, and chemosensing. Currently, the majority of reported AIE-active molecules are based on either propeller-shaped rotamers or donor–acceptor molecules with strong intramolecular charge-transfer states. Here, we report a new design motif, where a fluorophore is covalently tethered to a quencher, to expand the scope of AIE-active materials. The fluorophore–quencher dyad (FQD) is nonemissive in solutions due to photoinduced electron-transfer quenching but becomes luminescent in the solid state. The intrinsic emission lifetimes are found to be within the microseconds domain at both room and low temperatures. We performed single-crystal X-ray diffraction measurement for each of the FQDs as well as theoretical calculations to account for the possible origin of the long-lived AIE. These FQDs represent a new class of AIE-active molecules with potential applications in organic optoelectronics

    The mean COHb levels at 0, 60, 65, 90, 120, and 150 min after acute CO poisoning.

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    <p>The values are means ± SDs (n = 8). <b><i><sup>*</sup></i></b> comparison of the COHb levels in the CO group with those in the HOS group at each time point (<sup>*</sup> and <sup>**</sup> indicate P < 0.05 and P < 0.01, respectively).</p

    Changes in arterial oxygen partial pressure (PaO<sub>2</sub>) and arterial oxygen saturation (SaO<sub>2</sub>).

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    <p>The mean PaO<sub>2</sub> levels at 0, 60, 65, 90, 120, and 150 min after acute CO poisoning (A). The mean SaO<sub>2</sub> level at 0, 60, 65, 90, 120, and 150 min after acute CO poisoning (B). The values are means ± SDs (n = 8).<b><i><sup>*</sup></i></b> comparison of the PaO<sub>2</sub> or SaO<sub>2</sub> values of the CO group with those of the NC group (<sup>**</sup> indicates P < 0.01). <b><i><sup>#</sup></i></b> comparison of the PaO<sub>2</sub> or SaO<sub>2</sub> values of the HOS group with those of the O<sub>2</sub> group (<sup>#</sup> and <sup>##</sup> indicate P < 0.05 and P < 0.01, respectively). <b><i><sup></sup></i></b>comparisonofthePaO<sub>2</sub>orSaO<sub>2</sub>valuesoftheO<sub>2</sub>groupwiththoseoftheCOgroup(<sup></sup></i></b> comparison of the PaO<sub>2</sub> or SaO<sub>2</sub> values of the O<sub>2</sub> group with those of the CO group (<sup></sup> and <sup></sup> indicate P < 0.05 and P < 0.01, respectively).</p

    Spatial learning and memory.

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    <p>The means of escape latency on days 11-15 (A) and 26-30 (B) after acute CO poisoning. Swimming time spent in quarter 4 on days 15 and 30 after acute CO poisoning (C). The values are the mean ± SD (n = 3 or 4). <b><i><sup>*</sup></i></b> comparison of the swimming times spent in quarter 4 by the CO or O<sub>2</sub> group with those by the NC group (<sup>*</sup> indicates P < 0.05). <b><i><sup>#</sup></i></b> comparison of the swimming times spent in quarter 4 by the HOS group with those by the CO group (<sup>#</sup> indicates P < 0.05). <b><i><sup></sup></i></b>comparisonoftheswimmingtimesspentinquarter4bytheHOSgroupwiththosebytheO<sub>2</sub>group(<sup></sup></i></b> comparison of the swimming times spent in quarter 4 by the HOS group with those by the O<sub>2</sub> group (<sup></sup> indicates P < 0.05).</p
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