Search

The pronounced exciton binding energy (Eb) in covalent organic frameworks (COFs) results in significant energy loss, thereby constraining the photocatalytic efficiency of COFs. Herein, triphenylamine is employed as an electron donor, while triphenyltriazine served as an acceptor; benzene, naphthalene, and anthracene are utilized as π‐bridges with progressively increasing conjugation to synthesize a series of D‐π‐A structured COFs photocatalysts (COF‐1, COF‐2, and COF‐3). The correlation between π‐bridge structures and Eb is systematically examined through the removal of hexavalent uranium U(VI) from tailings wastewater under visible light irradiation as a model reaction. Notably, an increase in π‐bridge conjugation initially enhanced and then diminished the photocatalytic properties of these three catalysts. This phenomenon can be attributed to the fact that coplanarity within the COFs frameworks does not consistently improve with greater π‐bridge conjugations; specifically, COF‐2 featuring a naphthalene π‐bridge exhibited the smallest dihedral angle. The reduced dihedral angle facilitated a more planar and delocalized electron transport pathway between donor and acceptor moieties, leading to decreased Eb and inhibited exciton recombination. Consequently, COF‐2 demonstrated exceptional photocatalytic reduction of U(VI), achieving efficiencies 1.8 times and 1.5 times greater than those of COF‐1 and COF‐3, respectively. This approach offers novel insights into mitigating Eb in COFs‐based photocatalysts. [ABSTRACT FROM AUTHOR]

The aim of the present study was to develop a rapid, specific and sensitive LC–MS/MS method for the determination of DPHB [7‐(4″‐hydroxy‐3″‐methoxyphenyl)‐1‐phenyl‐4‐hepten‐3‐one] in rat plasma using yakuchinone A as an internal standard (IS). n‐Hexane was used for the extraction of DPHB from rat plasma. Chromatographic separation of DPHB was achieved using a Kinetex XB‐C18 column (2.10 × 50 mm, 2.6 μm) at 40°C. The mobile phase consisted of water (containing 0.1‰ formic acid, A) and acetonitrile (containing 0.1‰ formic acid, B) under a gradient elution at a flow rate of 0.3 mL min−1. Positive electrospray ionization and multiple reaction monitoring mode were used for detection. The selected precursor ion to product ion pairs, m/z 311.3 → 137.0 for DPHB and m/z 313.1 → 137.0 for yakuchinone A, were monitored. Good linearity was observed over the concentration range from 2 to 2000 ng mL−1 (r = 0.9969). The recovery efficiency of DPHB from rat plasma was 54.8–69.7%, while the matrix effect ranged from 99.7 to 113%. Intra‐ and inter‐day precision and accuracy values were within ±15% at three different quality control concentration levels. This validated method was successfully applied to pharmacokinetic studies in rats after a single p.o. or i.v. dose of DPHB solution. The route of administration significantly influenced systemic exposure to DPHB, and low bioavailability of DPHB was observed. The method developed here will be further improved and used in future pharmacokinetic studies. [ABSTRACT FROM AUTHOR]