Journal of Photochemistry and Photobiology A-chemistry最新文献

AIE-ESIPT active Schiff base luminescent organic materials (LOM) have significant advantages and applications. Still, tuning their emission in the long-wavelength region (>600 nm) while maintaining low molecular mass remains challenging for the research community. Recently, researchers have found excellent capabilities like high CT nature, red-shifted emission, and large stokes shift in meta-fluorophores. However, such studies on the role of meta substitution, especially in the case of AIE-ESIPT active Schiff base LOM, have just been explored. Herein, we have presented a case study on the malonitrile-substituted regioisomers (p-BK and m-BK) based on the SDPA skeleton, a promising copper ion-sensing skeleton. It was found that the emission in m-BK is almost ∼ 50 nm red-shifted with approx. ∼ 200 nm stoke shift, compared to the p-BK. Although changing substituents from para to meta changes the aggregation behavior but, the selectivity remains identical towards copper ions. The practical sensing applicability of both isomers was analyzed in various environments, and bioimaging analysis in HeLa cells were performed to prove the promising nature of the SDPA skeleton. In sum, this case study highlighted the potential of unexplored meta-fluorophores, which can open up new avenues for researchers to create and design new AIE-active LOMs with desired emission wavelengths.

As one of the most widely used antibiotics, sulfamethoxazole (SDZ) poses significant health risks to the ecological environment by causing harm to aquatic organisms and accelerating evolution of antibiotic resistant bacteria. Metalloporphyrin hydrogen-bonded organic framework (PFC-72) demonstrates promising prospect in the field of photocatalysis owing to its high specific surface area, wide light harvesting range, stable physical and chemical properties, and semiconductor properties. Herein, we constructed an efficient photocatalyst PFC-72/g-C₃N₄ by one-step solvent thermal method for photocatalytic degradation of SDZ. When doping content of PFC-72 is 10 %, photocatalytic degradation efficiency of SDZ can reach 96.82 % after 120 min of visible light irradiation, and PFC-72/g-C₃N₄ exhibits excellent structural stability. The photocatalytic efficiency of SDZ is improved by increasing specific surface area, enhancing absorption range of visible light, and inhibiting recombination of photogenerated electron-hole pairs. In addition, photodegradation pathways of SDZ in PFC-72/g-C₃N₄ was determined by UPLC-MS/MS analysis. Finally, dominant reactive species (·O₂⁻, h_VB⁺, and ·OH) in the system were detected through free radical masking experiments, and photocatalytic mechanism was clarified. This work investigates a novel and efficient porphyrin-HOF based photocatalyst, which has great potential for degradation of SDZ.

Nonsymmetric 2-aryl (benz)imidazole derivatives were previously synthesized via C-H/N-H annulation of imidazole derivatives from lapachol moieties with internal alkynes as an efficient tool to increase the π-system of lapimidazole derivatives. To investigate their photophysical properties, time-resolved and steady-state fluorescence measurements were carried out on dropcast film, powder, and diluted solution. Despite having the same number of single and double bonds, slight differences in their structures lead to distinct photophysical properties. The time-correlated single-photon counting measurements also demonstrated that the aspects of the temporal decay curves are dependent on the treatment of the samples during the measurements. The decay curves were relatively well fitted using an alternative method based on the exponentially modified Gaussian function, giving rise to a more complete set of fitting parameters. Finally, theoretical calculations corroborate that small structural changes in molecules can significantly alter their conformational dynamics, electronic spectra, and overall electronic behavior and stability.

Nanostructured CdS-based photodetectors have been focused on recent years because of their high photosensitivity and quick response time. This work reports the photodetector characteristics of CdS thin films prepared using a nebulizer-assisted spray pyrolysis technique by varying substrate temperatures. The X-ray diffraction (XRD) pattern of CdS films exhibits hexagonal structure with orientation along the (0 0 2) plane and CdS films deposited at 450 °C exhibits a higher crystallite size of 53 nm. Morphological analysis shows that the small grains become large spherical flakes at higher substrate temperatures. The optical studies showed that around the visible region, the films exhibit solid optical absorbance, and when substrate temperatures rise to 450 °C, the energy bandgap value decreases to 2.29 eV. The photoluminescence (PL) spectra exhibit two emission peaks: a broad peak at 525 nm and a sharp dominant peak at 680 nm. The CdS thin film deposited at 450 °C produced the highest photoresponsivity (R) of 37.1 × 10^-2 A/W, detectivity (D*) of 268 x10⁸ Jones, external quantum efficiency (EQE) of 120 %, and response/recovery times of 0.92/0.28 s under 532 nm illumination. The study suggests that CdS thin films are suitable for visible photodetector applications due to their simple and cost-effective production process.

The development of fluorescent probes for prompt and accurate arginine (Arg) detection with high selectivity and sensitivity is in great demand due to the critical roles and implications of Arg for health. In this paper, a new coumarin-derived fluorescent probe, CL, was designed and synthesized. It was efficient for the rapid and specific detection of Arg in MeCN/H₂O (6:4, v/v), with a low detection limit of 0.78 μM and a short response time of less than 10 s. Probe CL was stable at pH 3–10 and exhibited excellent anti-interference from competitive amino acids, including lysine, histidine, cysteine, homocysteine, glutathione, glycine, glutamic acid, valine, tyrosine, tryptophan, leucine, phenylalanine, aspartic acid and methionine. Density-functional theory (DFT) calculations investigated and verified the sensing mechanism. Considering that probe CL features multiple advantages, including high specificity, emission at a long wavelength of 642 nm with a massive Stokes shift of 272 nm, fast response and a broadly applicable pH range, this study provides a new idea for the development of susceptible and selective detection method for Arg.

Zinc oxide thin films made by pulsed reactive magnetron sputtering combined with RF ECWR plasma on FTO or ITO substrates exhibit high photoelectrochemical activity for water splitting under UV light, but are unstable against photocorrosion. It can be suppressed by a protective layer of SnO₂ made by atomic layer deposition. The SnO₂ layer is quasi-amorphous in the as-received state, but the thermal treatment causes partial crystallization to cassiterite, without significant change of the optical band gap. Ferrocene in acetonitrile electrolyte solution is a useful redox probe for the blocking-quality tests of thin films of n-semiconductors. Both ZnO and SnO₂ are sensitive to irreversible electrochemical doping at potentials negative to the flatband potential. The flipping of electrochemical work functions of the Zn-terminated (0001) and O-terminated (000–1) faces of ZnO (wurtzite) takes place in acetonitrile vs. aqueous electrolyte solutions. The potentials for photocurrent onset are near the flatband potentials in an aqueous electrolyte solution for both ZnO and SnO₂.

A sustainable and eco-friendly approach was developed for the fabrication of red emissive carbon dots via microwave-assisted method using Grewia asiatica fruits as a source. The as-prepared Grewia asiatica-carbon dots (GA-CDs) exhibited red emission at 672 nm upon the excitation at 420 nm with a quantum yield of 21 %. The characteristic emission intensity of GA-CDs (λ_Em = 672 nm) is selectively quenched by quinalphos (QLP) pesticide via inner filter effect. The as-prepared GA-CDs serve as a versatile turn-off fluorescent probe for QLP sensing, displaying wider linear range (0.25–60 μM) with an impressive detection limit of 0.00159 μM. The integration of GA-CDs with fluorescence spectrometry offers to establish a rapid, simple and miniaturize analytical strategy for QLP assay in vegetable, water and soil samples. Furthermore, the bioimaging and cytotoxicity characteristics of GA-CDs were evaluated on yeast cells and lung cancer cells, respectively. This method provides a facile and convenient pathway for the on-site detection of QLP in food and agriculture samples.

The pervasive presence of valsartan (VAL), a widely used antihypertensive pharmaceutical compound, in aquatic environments has prompted concerns due to its low biodegradability and potential environmental impact. Emerging contaminants such as VAL necessitate advanced remediation methods beyond conventional wastewater treatments. In this study, the degradation of VAL in water matrices was explored utilizing a combination of molecular imprinting (MI) and heterogeneous photocatalysis, excited by different light-emitting diodes (LEDs) at 407 nm (40.55 W/m⁻²(−|-)), 530 nm (83.04 W/m⁻²(−|-)), and 355 nm (16.43 W/m⁻²(−|-)). The concept of MI was applied in the preparation of a TiO₂-based photocatalyst bearing VAL as a template. The encapsulation was carried out through an acid-catalyzed sol–gel route. The photocatalyst was characterized by surface area, pore volume, zeta potential, Fourier transform infrared spectroscopy, X-ray diffraction, and band gap measurements. The results obtained indicate that the radiation energy in the visible region is effective for degrading VAL. More specifically, the results obtained from differential pulse voltammetry indicate the consumption of VAL present in the modified electrode as well as the oxidation of the tertiary amine group of the molecule of VAL in addition to interactions between the drug and the network structure of the MI under light stimulation. Under the experimental conditions, the present photocatalyst system demonstrates the feasibility of VAL degradation under LED irradiation (change in anodic current was 15 % after 30 s under stimulation by LED light in the visible region). The viability of combining both concepts in the case-study of VAL as pollutant target added by the evaluation of the potentiality of employing LED irradiation.

In this work, the solvent effect on the excited-state intramolecular proton transfer (ESIPT) mechanism of the derivative (BTEP) based on 2-(2′-hydroxyphenyl)benzimidazole (HBI) modification in cyclohexane, dichloromethane and acetonitrile solvents has been investigated by utilizing the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The detailed study of the main geometrical parameters, infrared (IR) vibration spectra, and reduced density gradient (RDG) versus Sign(λ₂)ρ(r) scatter plots related to intramolecular hydrogen bond (IHB) reveals that the IHB strength of BTEP is enhanced in the excited state comparing with that in the ground state and that the magnitude of the enhancement decreases as solvent polarity increased. In addition, analysis of the potential energy curves (PECs) at the S₀ and S₁ states revealed that the energy barrier of the ESIPT reaction increases with increasing solvent polarity. These analyses have shown that increasing solvent polarity makes the ESIPT reaction increasingly difficult, and we hope that our study can provide guidance for subsequent research into further application of BTEP to fluorescent probes.

Y6, a highly efficient non-fullerene acceptor, could present distinctly different power conversion efficiency in organic solar cells when its alkyl side chains are replaced by others. However, the underlying mechanism is still unclear. To dissect this point, ten kinds of Y-series acceptors with variant side chains are studied. The density functional theory is used to calculate their ground geometry, frontier molecular orbital, ultraviolet–visible absorption spectra, the free energy of solvation, intramolecular electron transfer, and electronic structures on the excited state in chloroform. Results reveal that the presence of the branched R1 could reduce the dihedral angle and balance the planarity of molecular skeletons. The free energy of solvation is less than −1.5 eV and R2 has a greater impact on it than R1. Acceptors with longer R2 have better light absorption between 400 nm and 600 nm. Molecular dynamics simulation is also applied to the blending films with these acceptors and PM6. Molecules that possess branched R1 and longer R2 have a better morphology and are found to be promising candidates for highly efficient acceptors.