Journal of Photochemistry and Photobiology A-chemistry最新文献

Avobenzone was derivatized to avo-glycerol by replacing the p-methoxy group with glycerol at the ortho position. Avo-glycerol exhibited absorption in the UVA range (315–400 nm), similar to avobenzone, indicating good UVA coverage. Unlike avobenzone, a solution of avo-glycerol in an aprotic solvent demonstrates remarkable photostability, with no significant decrease in absorbance at the UVA range after 6 h irradiation. This suggests that the hydroxyl group in avo-glycerol functions as an efficient acid-base catalyst in enolization. Consequently, the rapid enolization of the photochemically generated keto form prevents its accumulation. This inherent photostability of avo-glycerol eliminates the need for photo stabilizers in sunscreen formulations and provides greater flexibility in selecting other sunscreen components.

Due to their exceptional intrinsic optical characteristics, molybdate compounds have aroused significant attention in recent years for their effective up and downconversion luminescence. In the present study, a series of xEr³⁺/Yb³⁺ (x = 0.5 %, 1 %, 2 %, 4 % and Yb³⁺ =15 %) doped CaMoO₄ nanophosphors synthesized through a microwave assisted approach and subsequently the comprehensive analysis of the functionalities such as optical properties, antibacterial traits and their integration with temperature sensing, have been explored. Furthermore, the structural refinement confirms the occurrence of tetragonal scheelite phase of the prepared materials. The morphology of the material was identified by FE-SEM and HR-TEM analysis which reveals particles are in spherical shape. Up-conversion luminescence intensities were found to be dependent on doping concentration, laser excitation power and external temperature upon 980 nm light excitation. The temperature sensing response of the optimized sample was examined based on intensity ratio of two emission bands that involves thermally connected energy levels of Er³⁺ ion. The maximum absolute sensitivity of 10.74 × 10⁻³ K⁻¹ (at 500 K) was found, demonstrating its potential application in high temperature thermometry. The comprehensive analysis and the outcome of the present study suggests the potential prospect of the as-synthesized material in food preservation, medical equipment, water treatment, and as an optical coating agent for solid state luminous devices.

Liquid electrolytes in dye-sensitized solar cells (DSSCs), while effective in minimizing recombination of TiO₂ conduction band with redox couple (I⁻/I₃⁻), suffer from leakage and evaporation issues, hindering commercialization. Although solid-state electrolytes were introduced as an alternative, their performance is constrained by poor electrode contact. To solve these issues, gel polymer electrolytes (GPE) have been formulated based on guar gum (GG) crosslinked with poly (ethylene glycol) (PEG 200) incorporating potassium iodide (KI) as the doping salt. The incorporation of PEG 200 into the GPE allows a stable gel polymer electrolyte to form by using dimethyl sulfoxide (DMSO) as the organic solvent. The GPE boasts a structure free from leakage, showcases captivating ionic conductivity and thermal stability. Comprehensive structural and thermal analyses, including Fourier Transform Infrared spectroscopy (FTIR), Differential Scanning Calorimeter (DSC), and Thermogravimetric Analysis (TGA) have been carried out. The electrochemical properties of the GPE were also studied via Electrical Impedance Spectroscopy (EIS) and are significantly enhanced with higher concentration of KI introduced into the GPE. The highest ionic conductivity (σ) value of 9.76 × 10⁻³ S cm⁻¹ is obtained in the GPE contained 40 wt% KI, with an efficiency of 5.65 %. Importantly, this study introduces a better and effective approach for designing electrolyte materials with high ionic conductivity, efficiency, and stability in DSSC.

H₂O₂ plays an important role in a variety of physiological processes, but its overproduction or accumulation can lead to oxidative damage and related diseases, so it is crucial to establish accurate H₂O₂ detection methods. Fluorescence sensing as a potential method, the design and modulation of its luminescent properties are crucial to the detection results. In this work, we investigated the sensing mechanism of a novel H₂O₂ fluorescent probe (P1) and examined the role of substituent effects in modulating the fluorescence properties of its reaction products. The results show that the non-fluorescence property of the probe is due to twisted intramolecular charge transfer (TICT) mechanism resulting from a torsion of the excited state molecular conformation, and the fluorescence turn-on upon recognition of H₂O₂ by the probe is due to the reaction product (BBYI1) following the excited state intramolecular proton transfer (ESIPT) process. When the substituent is an electron-donating group, the energy barrier of the ESIPT reaction is lowered, promoting luminescence, while the electron-withdrawing group has the opposite effect. In summary, the present work may offer a theoretical foundation for the development of more sensitive fluorescent probes for ESIPT-based H₂O₂ detection.

In this work, a novel copper decorated cuprous oxide–carbon nitride (Cu@Cu₂O-g-C₃N₄) plasmonic p-n heterojunction was prepared by solvothermal method using pre-synthesized carbon nitride and Cu@Cu₂O precursors as raw materials. The morphology observation for the sample exhibits that Cu₂O precursor is dispersed from micrometer octahedrons to the particles with the sizes of 20 ∼ 200 nm under action of dimethylformamide, forming a close contact between Cu nanoparticles, Cu₂O particles and g-C₃N₄ stacking flakes. The results of photodegradation shown that 96.4 % of 10 mg·L⁻¹ tetracycline (TC) solution was decomposed within 60 min and degradation rate decreased by 9.2 % after five cycles. Photoelectrochemical characterizations indicated that photocatalytic performance of Cu@Cu₂O-g-C₃N₄ was attributed to high-efficiently charge transfer base on the synergistic effect of heterojunction and plasmon resonance. The formation of p-n type built-in electric field between Cu@Cu₂O and g-C₃N₄ enhances photocatalytic oxidative and reductive ability of the catalyst, and dual coupling effects induced by the localized surface plasmon resonance of Cu nanoparticles promote the amount of photogenerated electrons. This work provides a strategy for preparing efficient p-n heterojunction photocatalysts with plasma coupling effects by reconstructing the junction interface using facile solvothermal method.

We report the experimental study of fluorescence properties of three porphyrazine derivatives, distinct in the number of fused aromatic rings in aryl groups contained in the macrocycle frame and/or presence of Pd in the macrocycle, in solutions with biological molecules and in methanol-glycerol mixtures. Spectral and lifetime fluorescence analysis has revealed that all three pigments demonstrated two fluorescence transition bands from the first S₁ and the second S₂ electronic excited states to the ground state S₀, and thus followed the anti-Kasha’s rule. Strong dependence of the quantum yield and lifetimes in the S₁ → S₀ fluorescence band on solution viscosity was observed. A significant increase of the fluorescence decay times and fluorescence intensity with albumin concentration and with presence of other biological molecules in solution was observed as well. A model of the low-laying energy states of porphyrazine derivatives has been developed for elucidation of the fluorescence properties observed, that took into account several radiative and non-radiative relaxation channels in molecular excited states. In particular, the model suggests that the first electronic excited state consists of planar and bent conformations separated by a potential energy barrier and shows a typical molecular-rotor behavior as a function of solution viscosity. Potential applications of the porphyrazine pigments as viscosity sensors and fluorescence probes were considered.

The work designed and described here is for the effective recognition of cyanide ion. A novel core (PC) with coumarin moiety as a signaling unit and pyridinium as an acceptor unit and these moieties linked by π-conjugation. In which CN⁻ ion binds in the pyridine ring via nucleophilic addition and produces changes that are captured by different techniques to prove its sensing efficiency. The probe displays a visual color variation to pale orange from purple and also exhibits blue fluorescence from red fluorescence upon cyanide addition. The probe PC sensing ability towards CN⁻ ion has been confirmed by various spectral measurement. In UV–visible technique, a blue shift was observed by the probe with CN⁻ ion. In fluorescence measurements, a peak appeared at 704 nm, which corresponds to the probe encountering a peak enhancement with the added cyanide ion. The binding stoichiometric ratio among the probe and CN⁻ ion is to be 1:1 in jobs method. The probes detection limit and binding constant were calculated to be 0.39 nM and 7.07x10⁴ M. The probe is used as a single component ink and injected into a cartridge and printed on paper which is used as a tool to detect cyanide in water. Besides, the probe successfully senses cyanide ion in various water samples.

The development of specific and visually detectable fluorophores for the accurate and rapid Pb²⁺ recognization is crucial. In this study, we introduced a novel isophorone-derived fluorescent probe, (E)-2-(3-(3-formyl-4-hydroxystyryl)-5,5-dimethylcyclohex-2-en-1-ylidene)malononitrile (YSQ), rationally designed for prompt and high-quality Pb²⁺ detection. YSQ demonstrated noticeable red emitting fluorescence enhancement upon Pb²⁺ interactions (upon binding, τ_avg 16.7 ns, Φ 12 %) with visible color changes discernible to the naked eye in MeOH/H₂O (v/v 9/1, pH 7.4, 0.2 mM). The probe YSQ achieved a quite low detection limit (LOD) of 18 nM and a high association constant of 2.93 × 10⁵ M⁻¹ towards Pb²⁺ using fluorescence titration. We proposed a binding mechanism of YSQ with Pb²⁺ ions, supported by the density functional theory (DFT/TD-DFT), ¹H NMR titration experiments, IR and HRMS analysis. In addition, a simple and affordable smartphone-supported specific Pb²⁺ detection technique was developed with visible color changes. Furthermore, this NIR emissive properties of YSQ offered broad potential applications in actual water sample and solid analysis, bio-imaging and test strips.

Certain anions play a vital role in metabolic reactions in our body, but the cyanide ion is highly toxic and poisonous to humans, animals, and the environment even at extremely low concentrations. To detect CN−ions, a highly sensitive electron donor-π-acceptor molecular system (IC) was designed based on the carbazole electron donor and 1,3-indanedione electron acceptor. The IC molecular probe was synthesized through simple organic transformations with good yields and characterized by all spectroscopic methods, including single-crystal X-ray diffraction. The IC probe molecule absorbs in the UV–visible region (200–550 nm), and fluorescence emission encompasses 400–750 nm with LE and CT emission bands. A systematic study suggests that the addition of cyanide ions caused both longer wavelength absorption bands and CT fluorescence emission intensity to decrease. Cyanide ion detection can be visualized with the naked eye, where the yellow color of the IC probe solution changes to colorless upon adding cyanide ion solution. Both UV–visible and fluorescence emission spectral changes with the addition of cyanide ions are attributed to the nucleophilic addition of cyanide at the vinylic carbon, which is confirmed by the ¹H NMR, HRMS and fluorescence lifetime studies. The cyanide ion detection limit of the IC has been estimated to be 0.43 µM, far below the WHO permissible limit for cyanide ion concentration in potable water, thus broadening the utility of the IC probe in detecting cyanide in Tapioca. A prototype TLC testing strip has been fabricated for the qualitative determination of cyanide in THF/water medium.

Black phosphorus (BP) is highly regarded in photocatalysis for its bandgap thickness dependency, high hole mobility, and broad visible light absorption. This study introduces a simple hydrothermal method to construct a BP QDs/BiVO₄ direct Z-scheme heterojunction. The composite’s crystal structure, morphology, and photochemical properties were comprehensively characterized. The photocatalytic activity was evaluated using Rhodamine B (RhB) degradation under visible light. Notably, BP QDs_0.12%/BiVO₄ exhibited exceptional performance, achieving a 95.4 % RhB degradation after 100 min, three times higher than BiVO₄ alone. The direct Z-scheme heterojunction played a pivotal role in facilitating O₂⁻ and h⁺ involvement in the degradation process. The interfacial interaction between BP QDs and BiVO₄ significantly enhanced BiVO₄′s visible light absorption, preserving its strong oxidation–reduction capacity. This enhancement was further corroborated by DFT simulation calculations. Overall, this study presents a novel approach for constructing efficient Z-scheme photocatalysts based on BP QDs, laying a solid foundation for their application in the field of photocatalytic degradation.