Flexible polyurethane foam (FPUF) has many advantages such as lightweight, low density and high specific strength and is widely used in furniture, automobile industry, construction and ...transportation. However, FPUF is extremely flammable in the air, and a large amount of toxic gas will be generated when it is burned. The fire protection technology of FPUF has attracted more and more attention. Generally, it is an effective method to improve fire protection of FPUF by introducing additive flame retardant. As a relatively new approach, layer-by-layer (LBL) self-assembly technology is widely used in research fields such as biology, materials and nanoscience. In this work, the research and application of LBL self-assembly technology in the field of flame-retardant FPUF were described, and zero-dimensional, one-dimensional, two-dimensional nanomaterials, one- and two-dimensional nanocomposites systems and other self-assembly systems in flame-retardant FPUF were introduced in detail. The flame-retardant mechanism of flame-retardant FPUF systems was also systematically analyzed, and finally, the development of LBL self-assembly technology in flame-retardant FPUF was prospected.
A capping moiety, playing a role of the brake, slowed down the rotation speed of the cyclodextrin of a cyclodextrin-cucurbit6uril-cowheeled 3rotaxane. Lowering the temperature further stopped the ...rotation at the NMR timescale.
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Several cyclodextrin-cucurbit6uril-cowheeled 4rotaxanes were synthesized through the cucurbit6uril-templated azide-alkyne 1,3-dipolar cycloaddition. The intramolecular interaction between the aromatic axle and the capping groups of cyclodextrin moieties was investigated by UV–vis, fluorescence, circular dichroism and NMR spectroscopic studies. The rotational kinetic of the wheel around the axle can be manipulated by adjusting the temperature. The capping group apparently slowed down the rotation of the wheel, playing a role of the brake, and lowering the temperature can stop the rotation of the wheel on the NMR timescale.
The design and development of specific recognition and sensing systems for biologically important anionic species has received growing attention in recent years, as they play significant roles in ...biology, pharmacy, and environmental sciences. Herein, a new supramolecular sensing probe L1 was developed for highly selective differentiation of nucleotides. L1 displayed extremely marked absorption and emission differentiation upon binding with nucleotide homologs of AMP, ADP, and ATP, due to the divergent spatial orientations of guests upon binding, which allowed for a naked-eye colorimetric differentiation for nucleotides. A differentiating mechanism was unambiguously rationalized by using various spectroscopic studies and theoretical calculations. Furthermore, we successfully demonstrated that L1 can be applied to the real-time monitoring of the enzyme-catalyzed phosphorylation/dephosphorylation processes and thus demonstrated an unprecedented visualizable strategy for selectively differentiating the structurally similar nucleotides and real-time monitoring of biological processes via fluorescent and colorimetric changes.
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•Bis-quinoline CDXs as sensing probes to differentiate the nucleotide homologs in water•Its responses in the visible range allowed for a naked-eye colorimetric differentiation•The mechanism is proposed based on divergent spatial orientations of guests binding•Differentiation is realized by in situ enzymatic ATP hydrolysis and AMP phosphorylation
Analytical Chemistry; Analytical Chemistry Applications; Chemistry
Pillar5arene-based molecular universal joints (MUJs), bearing fused crown ether subring (MUJ1 and MUJ3) or a ring without ether oxygen atom (MUJ2), were synthesized and enantio‑differentiated. ...Significant chiral inversion was observed for the crown ether-fused MUJs upon the addition of equivalent cations Na+, showing an anisotropy (g) factor of 0.014, while alkyl subring-fused MUJ2 showed no CD inversions. Unprecedentedly, sodium ion triggered rolling-in motion of the subring to the pillar5arene cavity was verified, and the synergistic noncovalent interaction of cation-π interactions and CH···π interactions were responsible for the stabilized self-included conformers. The addition of MeOH or competitive hosts 15-crown-5 ether disassembled the complex of MUJ1 and Na+ followed by a rolling-out of the subring, which made the sodium-ion triggered chiroptical switching reversible.
Switching of the chiroptical properties of a molecular universal joint was triggered by sodium ion resulting from the synergistically stepwise complexing. Display omitted
Pillar5arene-based molecular universal joints(MUJs),bearing fused crown ether subring(MUJ1 and MUJ3)or a ring without ether oxygen atom(MUJ2),were synthesized and enantio-differentiated.Sig-nificant ...chiral inversion was observed for the crown ether-fused MUJs upon the addition of equivalent cations Na+,showing an anisotropy(g)factor of 0.014,while alkyl subring-fused MUJ2 showed no CD inversions.Unprecedentedly,sodium ion triggered rolling-in motion of the subring to the pillar5arene cavity was verified,and the synergistic noncovalent interaction of cation-π interactions and C-H…π in-teractions were responsible for the stabilized self-included conformers.The addition of MeOH or compet-itive hosts 15-crown-5 ether disassembled the complex of MUJ1 and Na+followed by a rolling-out of the subring,which made the sodium-ion triggered chiroptical switching reversible.
Room temperature phosphorescent (RTP) γ-CD-CB6-cowheeled 4rotaxanes were synthesized by implanting a naphthalene axle into the cavity of iodine-substituted γ-CDs. The strong green RTP was quenched ...exclusively by Trp while no RTP quenching was observed with other major physiological amino acids or with the Trp-containing protein HSA, demonstrating a highly specific sensing of free Trp.
Titanium carbide MXene quantum dots (QDs) were synthesized using an effective fluorine-free method as a biocompatible and highly efficient nanoagent for photothermal therapy (PTT) applications. In ...contrast to the traditional, hazardous and time-consuming process of HF pretreatment, our fluorine-free method is safe and simple. More importantly, abundant Al oxoanions were found to be modified on the MXene QD surface by the fluorine-free method, which endowed the QDs with strong and broad absorption in the NIR region. As a result, the as-prepared MXene QDs exhibited an extinction coefficient as large as 52.8 Lg
cm
at 808 nm and a photothermal conversion efficiency as high as 52.2%. Both the values are among the best reported so far. The as-prepared MXene QDs achieved simultaneous photoacoustic (PA) imaging and the remarkable PTT effect of tumors. Moreover, MXene QDs showed great biocompatibility without causing noticeable toxicity in vitro and in vivo, indicating their high potential for clinical applications.
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