Although lanthanoid metal–organic frameworks (Ln-MOFs)
have
been widely developed for white light-emitting diodes (WLEDs), the
color rendering index (CRI) values are still lower than 80. To overcome
this limitation, a series of CDs/Ln-MOFs hybrids, namely, CDs-2@Ln-MOF, CDs-3@Ln-MOF, and CDs-4@Ln-MOF
containing blue-emitting CDs and yellow-emitting bimetallic [(Eu1.22Tb0.78(1,4-phda)3(H2O)](H2O)2 were prepared via sonication at room temperature
to restrict the self-quenching of CDs in composite materials. The
as-synthesized composite materials were investigated by Fourier transform
infrared, powder X-ray diffraction, transmission electron microscopy,
scanning electron microscopy, and photoluminescence. The luminescent
color of the materials can be adjusted by varying the amount of CDs
and excitation wavelengths. The resulting CDs-3@Ln-MOF
achieved excellent CRI up to 93 with the ideal Commission International
ed’Eclairage coordinate (0.334, 0.334) and appropriate correlated
color temperature (CCT) (5443 K). In addition, the tunable multicolored
luminescence based on single and bimetallic Eu
x
Tb2–x
(1,4-phda)3(H2O)](H2O)2, x = 0, 0.73, 1.22, 1.57, 1.94, and 2, were applied as the luminescent
security inks for anti-counterfeiting application through encoding/decoding
and rewritable data.
A simple, rapid, highly selective, and real-time determination of water is urgently required for preventing danger from water contamination in materials. Herein, the excited-state proton transfer (ESPT) concept-based luminescent sensor [Cd 2 (2,5-tpt)(4,5-idc)(H 2 O) 4 ] (1) (2,5-tpt = 2,5-dihydroxyterephthalic acid and 4,5-idc = 4,5-imidazoledicarboxylic acid) has been designed for discriminative detection via enol−keto tautomerism. To improve the sensitivity, two-dimensional (2D) nanosheets of 1 have been synthesized by topdown liquid ultrasonic exfoliation technology for sensing water in dimethylformamide, which lead to fast detection (<30 s), high selectivity, broad-range detection (0−50% v/v), and a low detection limit value (0.25% v/v). This sensor can serve dual sensing mechanisms along with a luminescent color change via shifted emission (green→yellow) in low water content and a turn-off method in high water content. For ease of use, the test-strip paperbased 2D nanosheets of 1 have been prepared and applied for water detection with long-term stability, pH stability, and good reusability. On-site water detection in real time can be evaluated using a smartphone color-scanning application for quantitative scanometric assays coupled with test-strip paper-based 2D nanosheets of 1. Also, 1 can be utilized for a colorimetric luminescent thermometer in the ranges of physiological and high temperature with good linearity and recyclability.
A coordination
complex, lithium hepta(i-butyl)silsesquioxane
trisilanolate (1; Li-T7), a stable intermediate
in silsesquioxane (SQ) syntheses, was successfully isolated in 65%
yield and found to be highly soluble in nonpolar solvents such as
hexane. The structure of Li-T7 was confirmed by NMR, IR
spectroscopy, matrix-assisted laser desorption ionization time-of-flight
mass spectrometry, electrospray ionization mass spectrometry, and
computational simulation, providing detailed elucidation of the intermolecular
self-association of the SQ cage with a box-shaped Li6O6 polyhedron through strong coordination bonds. After acid
treatment, Li-T7 undergoes lithium–proton cationic
exchange, yielding hepta(i-butyl)silsesquioxane trisilanol
(2; H-T7) quantitatively. The high yield of
H-T7 seems to be influenced by Li–O bonding in the
Li-T7 complex that affects the selective formation of hepta(i-butyl)silsesquioxane trisilanolate and the bulky i-butyl groups which may prevent decomposition or SQ cage-rearrangement
even at reflux under alkaline conditions. Single-crystal X-ray crystallography
confirms the presence of the dumbbell-shaped SQ partial cages through
strong intermolecular hydrogen bonds. Interestingly, lowering the
polarity of the reaction solution by adding dichloromethane results
in formation of the cubic octa(i-butyl)silsesquioxane
(3; T8) cage in a good yield (47%), which
is isolated by crystallization from the reaction solution.
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