2 research outputs found
Förster Resonance Energy Transfer from Quantum Dots to Rhodamine B As Mediated by a Cationic Surfactant: A Thermodynamic Perspective
Förster
resonance energy transfer (FRET) has attracted much
attention for its wide applications in the fields of bioimaging, bioanalysis,
etc. One of the critical problems in FRET is the construction of suitable
donor–acceptor pair. The fluorescent quantum dots (QDs) can
well meet the requirements both for a donor and an acceptor, owing
to their tunable emission and broad absorption. Besides, the QDs possess
high quantum yield, which highly benefits the FRET efficiency. In
this work, glutathione-capped CdTe QDs (GSH-CdTe QDs) was chosen as
the energy donor (D) and Rhodamine B (RhB) as the energy acceptor
(A). However, no FRET occurred when there were only QDs and RhB, even
though there was much overlap between the absorption spectrum of RhB
and the emission spectrum of QDs. Interestingly, after the addition
of a cationic surfactant, cetyltrimethylÂammonium bromide (CTAB),
FRET was induced favorably. Further understanding of this phenomenon
was studied by fluorescence spectroscopy, dynamic light scattering,
and zeta potential. The results indicated that QDs aggregated and
were cross-linked by CTAB due to electrostatic interactions. Then,
RhB was trapped in the aggregates. Therefore, QDs and RhB were pulled
closer to a reasonable distance and FRET happened prosperously. Notably,
thermodynamics in this process was well studied for an in-depth understanding.
This work will render the better design of donor–acceptor pairs
to overcome the long distances as well as the deep understanding of
FRET with spreading applications
Ni-Catalyzed Asymmetric Hydrogenation of α‑Substituted α,β-Unsaturated Phosphine Oxides/Phosphonates/Phosphoric Acids
Efficient Ni/(S,S)-Ph-BPE-catalyzed
asymmetric hydrogenation of α-substituted α,β-unsaturated
phosphine oxides/phosphonates/phosphoric acids has been successfully
developed, and a wide range of chiral α-substituted phosphines
hydrogenation products were obtained in generally high yields with
excellent enantioselective control (92%–99% yields, 84%−>99% ee). This method features a cheap
transition metal nickel catalytic system, high functional group tolerance,
wide substrate scope generality, and excellent enantioselectivity.
A plausible catalytic cycle was proposed for this asymmetric hydrogenation
according to the results of deuterium-labeling experiments