Radical anions of electron-deficient systems are widely used, but are easily reoxidized upon exposure to air. Therefore, the stabilization of radical anions under ambient conditions is of great significance, but still remains a scientific challenge. Herein, perylenediimide is employed to prepare a crystalline metal-organic framework for stabilizing radical anions without extensive chemical modification. The porous, three-dimensional framework of perylenediimide can trap electron donors such as amine vapors and produce radical anions in-situ through photo-induced electron transfer. The radical anions are protected against quenching by shielding effect in air and remain unobstructed in air for at least a month. Because of the high yield and stability of the radical anions, which are the basis for near-infrared photothermal conversion, the framework shows high near-infrared photothermal conversion efficiency (η = 52.3%). The work provides an efficient and simple method towards ambient stable radical anions and affords a promising material for photothermal therapy.
Lysophosphatidic acid (LPA) as the biomarker of early stage ovarian cancer is essentially difficult to detect due to lack of target spots. A dually crosslinked supramolecular hydrogel (DCSH) was developed to achieve sensing of LPA, which acts as a competitive guest molecule triggering the responsive crosslinking of the DCSH. Through this strategy, the surface plasmon resonance combined with optical waveguide spectroscopy could be used to quantitatively detect LPA with a responsive range covering physiological conditions (in pure form as well as mimicking LPA plasma solution) with high selectivity and sensitivity. LPA efficiently immerses into the host molecule β-cyclodextrin (β-CD) up to a 1:2 ratio by the competitive interaction mechanism, confirmed by one-dimensional nuclear overhauser effect spectroscopy (1D NOESY), highresolution mass spectrometry (HRMS), isothermal titration calorimetry (ITC), and computational simulation. Our method opens a new strategy to detect biomarkers without target spots and provides a platform for surface plasmon resonance (SPR)-based sensors measuring small molecules.
Developing a specific, ratiometric, and reversible detection method for metal ions is significant to guard against the threat of metal-caused environmental pollution and organisms poisoning. Here a supramolecular host-guest system (WP5⊃G) based on water-soluble pillar[5]arene (WP5) and water-soluble quaternized perylene diimide derivative (G) was constructed. Morphological transformation was achieved during the process of adding WP5 into G aqueous solution, and a fluorescence "turn-off" phenomenon was observed which was caused by supramolecular photoinduced electron transfer (PET). Meanwhile, hydrophobic effect and electrostatic interaction played important roles in this supramolecular process, which was confirmed by isothermal titration calorimeter (ITC) and ζ potential experiments. Furthermore, the supramolecular host-guest system could be a "turn-on" fluorescent probe for Fe ion detection through the process of interdicting supramolecular PET. Moreover, the Fe ion detection showed specific, ratiometric, and reversible performances with a detection limit of 2.13 × 10 M, which might have great potentials in biological and environmental monitoring.
A supramolecular circularly polarized luminescence (CPL) system was constructed based on the co-gelation of an achiral tetraphenylethylene derivative and chiral organic gelators of glutamic acid in chloroform. And the handedness of CPL can be inverted by stoichiometric ratio.
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