Journal of Photochemistry and Photobiology A-chemistry最新文献

Both SrNiO₃ perovskite and CeO₂ are materials suitable for photocatalytic purposes. In this work, the preparation and physicochemical characterization of bare SrNiO₃ and CeO₂ along with composites where CeO₂ was enriched with the perovskite from 15 to 70 % in mass of SrNiO₃ in the composite are described. The materials have been used for the photocatalytic oxidation of 2-propanol in gas–solid regime in the presence of UV-LED or simulated solar irradiation. The solids were characterized by XRD, SEM/EDX, N₂ adsorption/desorption and FTIR and UV–Vis diffuse reflectance spectroscopies. The composite containing 15 % w/w of SrNiO₃ and 85 % w/w of CeO₂ resulted the most active, giving rise the complete degradation of 2-propanol after 1.5 h or 6.0 h of irradiation by UV-LED and simulated solar light irradiation, respectively. Photocatalytic activity results are discussed considering the physical–chemical properties on the catalysts.

Solvation plays an important role in chemistry and biology. The role of the solvent is crucial in any chemical processes such as tautomerization that controls the structure and function of biomolecules. The current study aims to explore how different solvent medium affects the tautomeric forms of an antitumor drug, Imiquimod (IMQ). We have used several spectroscopical methods, including UV–Vis absorption spectroscopy, steady-state and time-resolved fluorescence spectroscopy, and quantum mechanical (QM) calculations. Our results revealed that solvent, indeed, plays a significant role in the modulation of the photophysics of the drug. IMQ has three emission bands in protic and aprotic solvents and two bands in non-polar medium associated with different forms of the drug. Using time-resolved technique, and comparing with the predicted lifetimes from QM calculations, we succeed to assign these three forms as cation, tautomer and neutral of IMQ with 1.6 ns, 2.0 ns and 4.0 ns lifetime values, respectively. Since IMQ is a nucleobase analogue and one of the most effective medications for skin tumors; these findings about which specie of IMQ is present in a given medium, and beyond, how the medium alters the photophysics of the molecule may provide deeper insights into its structure and function.

Herein, we reported the effect of electron withdrawing units, such as trifluoromethyl (CF₃) and cyanide (CN), substitution on a thermally activated delayed fluorescent (TADF) molecule (10-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl)-10H-phenoxazine (PXZ-OXD)). The addition of electron withdrawing units has increased the acceptor strength and reduced the interaction between PXZ and OXD, thus reducing the gap between the singlet and triplet states (ΔE_ST) of excitons. To understand the variation in the acceptor strength of PXZ-OXD as a function of its molecular structure and density of states, density functional theory (DFT) and time-dependent DFT (TDDFT) were conducted. Transition density matrix investigations revealed that the addition of −CF₃ and –CN to PXZ-OXD triggers CT excitons, while inducing lower ΔE_ST values. Particularly, the lowest ΔE_ST (0.05 eV) with a notable red shift in the emission spectrum was observed with 4′-CF₃PXZOXD. The delayed component lifetime of PXZOXD is found to be reduced after the substitution of −CNwhm and −CF₃. Despite the weak charge transfer transitions, the substitution of conjugative –CN group is found to be beneficial in improving the HOMO-LUMO overlap with a moderate decrease in reverse intersystem crossing (K_RISC), which attained enhancement in the photoluminescent quantum yield. Additionally, the substitution of the above electron withdrawing units on PXZ-OXD yielded a red shift in the electroluminescence spectrum. Furthermore, the external quantum efficiency (at 100 cd/m², i.e., EQE₁₀₀) of the 4′-CNPXZOXD-based organic light-emitting diode is found to improve by 21.13 % against the PXZOXD (16.9 %).

Twinned zinc cadmium sulfide (Zn_xCd_1-xS) has been widely investigated for efficient Cr(VI) reduction and H₂ production under light irradiation due to its inherent homojunctions. However, long-distance migration of charge carriers and relatively low conduction band level inevitably cause low photocatalytic reduction ability. Herein, we developed a DMF-involved one-step solvothermal strategy to introduce N heteroatoms into Zn_0.67Cd_0.33S crystals incorporated with dopant-induced S vacancies. The synergetic promotion of the elevated conduction band, coupled with the robust aggregation of interactants, effectively impeded the recombination behavior of charge carriers, leading to a notable increase in photocurrent density (∼2.4 times), electron density (∼2.8 times), and a higher photo-reducing potential. The optimal NZCS-10 demonstrated a superior photocatalytic Cr(VI) reduction efficiency of 99.32 % within 30 min, and rendered ca. 5.8- and 7.6-fold enhancement for H₂ evolution rate under alkaline and acidic conditions, respectively. This study provided a universal strategy for gaining highly reductive transition metal sulfides with more active sites.

The design, synthesis, and use of four new thiophene-based dispersed azo dyes with salicylic and carboxylic acid acceptors are shown in this work. The produced dyes exhibit a wide range of light absorption characteristics, including near UV–visible, and deep red wavelengths. PG9 and PG12, which are thiophene disperse azo dyes with carboxylic acid acceptor, showed red-shifted absorption, but PG10 and PG11, which are azo dyes with salicylic acid, showed blue-shifted absorption. The synthesized dyes exhibited good photostability in solvents. The experimental results are supported by theoretical results from Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT).

Furthermore, the dyes exhibit outstanding dyeability with percentage exhaustion characteristics of 90% when applied to acrylic, nylon, and polyester fabrics. Rich shades ranging from deep orange to black are seen in the dyed fabrics. Salicylic acid acceptor-dyed materials have higher K/S values when applied to nylon-dyed fabrics, while acrylic and polyester-dyed fabrics respond better to carboxylic acid acceptor dyes. The fabrics that have been colored display exceptional light, wash, and rubbing fastness. In light and wash fastness, polyester-dyed fabrics performed better than acrylic and nylon-dyed fabrics. Studies on UV protection show that fabrics with high UPF ratings can block damaging UV-A and UV-B radiation efficiently. All synthetic dyes have their antibacterial activity assessed using the AATCC 100 test method, which is associated with the HOMO-LUMO energy gap.

This paper presents a novel approach for enhancing the efficiency of dye-sensitized solar cells (DSSCs) through the co-sensitization of cyanoacetamide-based dyes DY-1 and DY-2 with N3 dye. The synthesis and characterization of DY-1 and DY-2 co-sensitizers are described and their potential applications in photovoltaic devices are investigated. The absorption properties of DY-1 and DY-2 were analyzed, revealing their efficient light absorption in the visible range. The co-sensitization of DY-1-2 with N3 dye demonstrated a significant enhancement in photovoltaic efficiency, ranging from 7.40 % to 7.92 %. The reasons for this efficiency enhancement were thoroughly analyzed and attributed to several factors. First, the combination of DY-1-2 with the N3 dye led to a broader light absorption spectrum, enabling more efficient utilization of incident photons. Additionally, co-sensitization facilitates efficient charge separation and injection processes, contributing to improved photocurrent. The acid-base co-sensitization approach further enhances the overall efficiency by maximizing the charge transfer and coverage on the semiconductor surface. This study sheds light on the development of novel sensitizers to enhance the performance of DSSCs, and the findings contribute to the advancement of photovoltaic devices.

Zinc phthalocyanine derivatives have unique structure and photophysical properties, which make them a remarkable potential in the fields of optoelectronics as well as biomedicine. In order to reveal the effect of the terminal substituents on the electron transition mechanisms, one-photon absorption (OPA) and two-photon absorption (TPA) processes of three zinc phthalocyanines modified with different terminal substituents (PcZn-0, PcZn-1 and PcZn-2) have been analyzed by using density-functional theory (DFT) in combination with the sum-over-states (SOS) model, the visualization of the transition density matrix (TDM) as well as charge density difference (CDD) calculations. Red-shifted OPA absorption peaks with enhanced intensities, have been observed in molecules PcZn-1, PcZn-2 with long terminal substituents. However, for TPA process, a more effective charge transfer over almost the entire molecule has been observed in PcZn-1 molecule with 4-methoxybenonic acid as terminal substituents. When H-atoms in the hydroxyl groups of four terminal 4-Methoxybenzoic acid groups were substituted by dispersed red-one chains, a limited range of intramolecular charge transfer and localized excitation inside the dispersed red-one chain were observed, leading to a localized excitation absorption peak and expanding the wavelength region of TPA response. Furthermore, terminal substituents with conjugated branches exhibit a stronger cooperative effect between the terminal chains and shows larger TPA response. On the contrary, excessive dihedral angles between different groups can weaken the conjugation degree of molecules and affect intramolecular charge transfer as well as TPA response.

Appling density functional theory together with basis set B3LYP/6-311G++(d,p), the organic compound Imiquimod was theoretically analyzed by spectroscopic and UV–Visible approaches and also structure optimization and contructural parameters have been done. Non-linear optics, Frontier Molecular orbitals, Molecular electrostatic potential (MEP) were computed using solvents inclusive of gas, water, chloroform, ethanol and acetone. Using TD-DFT with model IEFPCM, the transition spectra have been obtained. The electron interaction and reactive areas have been analyzed by NBO and Fukui methods. Using Multiwave function, the surface properties such as electron localization function, localized orbital locator, Electron density, TDOS, electrostatic potential and Non-covalent interaction have been carried out using solvents. Coulomb, dispersion and total energies were calculated, surface analysis and molecular interactions were carried out using Hirshfeld surface analysis. Using molecular docking, the appropriate docking sites have been identified.

We have developed two novel thermally activated delayed fluorescence (TADF) emitters, IQLO-PXZ and IQLO-DMAC, featuring an intramolecularly locked indeno[1,2-b]quinolin-11-one (IQLO) acceptor. Our comprehensive investigation, including structural analysis, theoretical calculations, and photophysical studies, aims to assess the viability of IQLO-PXZ and IQLO-DMAC as light emitters in electroluminescent devices. Unlike existing aryl ketone-based emitters, IQLO-PXZ and IQLO-DMAC exhibit red-shifted emission due to their structurally rigid and electron-deficient IQLO moiety. The stronger intramolecular charge transfer effect in IQLO-PXZ results in longer-wavelength emission compared to IQLO-DMAC. Both emitters demonstrate significant TADF properties, facilitating efficient triplet-to-singlet spin conversion. When utilized as the emissive core in electroluminescent devices, IQLO-PXZ and IQLO-DMAC achieved long-wavelength electroluminescence peaking at 612 nm and 578 nm, with commendable external quantum efficiencies of 10.3 % and 11.7 %, respectively. These findings underscore the potential of IQLO as an effective acceptor for constructing high-performance TADF electroluminescent materials.