3 research outputs found
Ligand Control of Copper-Mediated Cycloadditions of Acetylene to Azides: Chemo- and Regio-Selective Formation of Deutero- and Iodo-Substituted 1,2,3-Triazoles
The
participation of σ-monocopper and σ-bis-copper
acetylide in mechanistic pathways for copper-catalyzed cycloaddition
(CuAAC) reactions of acetylene with azides was probed by analysis
of deuterium distributions in the 1,2,3-triazole product formed by
deuterolysis of initially formed mono- and bis-copper triazoles. The
results show that, when Cu(Phen)(PPh3)2NO3 is used as the catalyst for reactions of acetylene with azides
in DMF/D2O, 1-substituted-5-deutero-1,2,3-triazoles are
generated selectively. This finding demonstrates that the Cu(Phen)(PPh3)2NO3-catalyzed cycloadditions utilize
monocopper acetylide as the substrate and produce 5-copper-1,2,3-triazoles
initially. Conversely, when DBU or Et3N is the copper ligand,
the process takes place through initial formation and cycloaddition
of bis-copper acetylide to produce 4,5-bis-copper-triazole, which
reacts with D2O to form the corresponding 4,5-bis-deutero-triazole.
Moreover, when C2D2 is used as the substrate,
Cu(Phen)(PPh3)2NO3 as the Cu ligand,
and H2O/DMF as the solvent, mono-C4-deutreo 1,2,3-triazoles
are generated in high yields and excellent levels of regioselectivity.
Lastly, CuAAC reactions of acetylene with azides, promoted by CuCl2·2H2O and NaI, yield 4,5-diiodo-1,2,3-triazoles
with moderate to high efficiencies
Engineering an Enzymatic Cascade Catalytic Smartphone-Based Sensor for Onsite Visual Ratiometric Fluorescence–Colorimetric Dual-Mode Detection of Methyl Mercaptan
Precise and reliable onsite detection of methyl mercaptan
(CH3SH) is of great significance for environmental surveillance.
Here, we synthesized a novel blue fluorescence nanozyme CeO2@TPE with high peroxidase-like activity by employing aggregation-induced
emission (AIE) tetraphenylethene (TPE) to embed into hollow CeO2 nanospheres. In the presence of ethanol oxidase (AOX) and o-phenylenediamine (OPD), we engineered an enzymatic cascade
activation ratiometric fluorescence–colorimetric dual-mode
system AOX/CeO2@TPE + OPD toward CH3SH. In this
design, CH3SH initiated AOX catalytic activity to convert
it into H2O2 for activating the peroxidase-like
activity of CeO2@TPE, producing •OH for
oxidizing the naked-eye colorless OPD into deep yellow 2,3-diaminophenazine
(DAP) with an absorption enhancement at ∼425 nm, companied
by a new emission peak at ∼550 nm to match with the intrinsic
emission at ∼441 nm for observing ratiometric fluorescence
response, enabling a ratiometric fluorescence–colorimetric
dual-mode analysis. Interestingly, both the ratiometric fluorescence
and colorimetric signals could be gathered for being converted into
the hue parameter on a smartphone-based sensor, achieving the onsite
visual fluorescence–colorimetric dual-mode detection of CH3SH in real environmental media with acceptable results. This
study gave a novel insight into designing target-responsive enzymatic
cascade activation system-based efficient and reliable dual-mode point-of-care
sensors for safeguarding environmental health