ChemPhotoChem最新文献

The photochemistry of resveratrol with singlet oxygen (¹O₂) under blue-LED irradiation is explored in the presence of three metal-free porphyrins as photosensitizers. Irradiation at 450 nm yields products of CC bond scission, 6-electron electrocyclic ring closure, and [4 + 2] cycloaddition, including benzaldehydes, 2,4,6-trihydroxyphenanthrene, and resveratrol cyclic endoperoxide. The selectivity of the process is controlled by the structure of the metal-free porphyrin and by the nominal capacity of the blue-LED photon. The scope of the reaction is extended to sustainable heterogeneous photosensitizers produced by immobilization of metal-free porphyrins on lignin, the most abundant polyphenol in nature characterized by beneficial photochemical properties.

Herein, how aggregation-dispersion behavior of fluorinated azobenzene derivatives 5 and 6 with an amphiphilic dodecaoctane substituent is affected by UV light irradiation and water is described. The influence of fluorine substituents on their photophysical properties, photoswitching differences, and aggregation in waterin-ground trans and excited cis-state is studied. Their photophysical and photoswitching properties are investigated under the polar MeOH and nonpolar solvent benzene and it is found that 6 shows different behavior as compared to 5 in both solvents. Further, to check their aggregation properties in MeOH, a competing solvent water is added. It is observed that in MeOH–H₂O solution (0.9-1.5 mL), compounds show a redshift with a decrease in the absorbance, and fluorescence emission is found. Further, dynamic light scattering shows the opposite behavior, 5 initially is in the macromolecular aggregated state both in trans and cis-states but the addition of water disperses the solution. However, 6 shows uniform micromolecular aggregated features in the trans-state and disperses further after the addition of water. Scanning electron microscopy images of 5 and 6 suggest aggregated patterns that change the morphology when added to water. IR, ¹H, and ¹⁹F NMR are done to understand the site of aggregation and intermolecular interactions.

Over the past decades, visible-light-driven reactions have emerged as a powerful tool in organic synthesis. Unlike traditional photoredox reactions that require additional catalysts or photosensitizers, electron donor–acceptor (EDA) complex-mediated photochemistry offers a simpler and more cost-effective approach to achieving diverse radical transformations without the need for noble catalysts. Among these, the use of boron-containing compounds as electron donors or acceptors in EDA complexes has garnered significant attention due to their unique properties. This review highlights recent advances in visible-light-induced EDA complex-mediated transformations involving boron-containing compounds, focusing on their applications in constructing CC and CB bonds and elucidating the underlying reaction mechanisms.

Organic nonlinear optical (NLO) materials with strong light-responsive properties have garnered significant attention in the field of optoelectronics due to their chemical tunability and cost-effective synthesis. Enhancing the NLO performance of these materials is essential to meet the growing demands in applications such as optical modulation and communication. Interestingly, twisted structures have been shown to alter NLO properties, offering a novel design approach. This review systematically examines recent advances in twisted D-π-A type organic chromophores for enhancing NLO performance, with a particular focus on the key mechanisms of molecular structure design and performance optimization. It provides a detailed discussion of the design strategies aimed at improving the NLO performance of twisted organic chromophores, highlighting the significance of twisted structures and electronic group design. The literature review indicates that optimizing twist angles, strengthening donor and acceptor group intensities, and optimizing π-conjugated bridges are effective ways to enhance NLO performance.

This study focuses on the impact of alternant phenyl substituents on the photophysical properties of tris-(2,4,6-trichlorophenyl)methyl (TTM)-type radicals. Most donor–acceptor-type luminescent systems show solvent-polarity sensitivity, which limits their applications. Herein, three alternate π-conjugated biphenyl/terphenyl substituents are attached to the TTM unit. Results reveal that connection modes and types of benzene ring derivatives lead to distinct charge transfer (CT) and locally excited state hybrid emitters due to the differences in conjugation degree. All three radicals exhibit polarity-insensitive red emission (626–690 nm), and their photoluminescence quantum yields (PLQYs) increase with solvent polarity. Specifically, linear-conjugated TTM-DPh has higher photostability but lower PLQY, while nonlinear-conjugated TTM-3DPh and TTM-TPh have nearly 10-fold higher PLQYs. The photophysical studies suggest that the conjugation degree and hybridization level between CT and ground states account for these properties.

Photochemistry has revolutionized the chemical industry by introducing sustainable and energy-efficient processes that are vital for the manufacture of advanced materials which align with Industry 4.0 standards. Among photochemical techniques, photopolymerization stands out as a rapid, controlled, and eco-friendly approach, making it particularly suitable for applications like 3D printing. This research in two-photon-induced photopolymerization for 3D microfabrication led to groundbreaking performance, thanks to the use of custom π-extended molecular architectures as photoinitiators. Building on these results, a photoactivable initiation system for photoinduced-atom transfer radical polymerization (photoATRP) is now reported using a similar π-extended photoinitiator. Through comprehensive optimization, we successfully created a functional multicomponent photoinitiating system, with its detailed mechanism thoroughly established in solution. By covalently attaching alkyl halides to glass surfaces, we were able to implement the surface-induced photo-ATRP technique to create customized brush polymer architectures. This work not only advances the understanding of photoATRP mechanisms but also introduces new strategies for functional surface engineering, with potential applications in two-photon-induced surface modification of 3D/4D structures via photoATRP.

Photocatalytic valorization of glycerol to value-added chemicals under ambient conditions is a promising approach for economically feasible and environmentally friendly biomass utilization. Herein, the successful synthesis of ≈2.6 nm AuPt alloy nanoparticles supported on MnO₂-Mn₃O₄ heterostructures via in situ transformation of α-MnO₂ is reported. Selective aerobic photocatalytic glycerol oxidation toward value-added C3 products has been achieved with AM 1.5G light irradiation under ambient conditions on these as synthesized 1 wt% AuPt/MnO₂-Mn₃O₄, which displays 2.3 and 6.5 times enhancement compared to that of AuPt/Mn₃O₄ and AuPt/MnO₂. A 74% overall C3 product selectivity (60% in terms of glyceric acid) has been achieved at 75% glycerol conversion after 4 h of photocatalytic reaction. Investigation results reveal that the formation of MnO₂-Mn₃O₄ heterostructures combines the local photothermal heating (primarily on MnO₂) synergistically with the photochemical catalysis (on Mn₃O₄), thus achieving enhanced photocatalytic glycerol oxidation. This study may provide guidance for future catalyst design, where photon-driven photocatalysis with phonon-driven photothermal effect can be seamlessly integrated to achieve maximal solar energy utilization and high photocatalytic efficiency.

A series of novel NaGdGeO₄: Tm³⁺, Dy³⁺ phosphors are prepared by a facile high-temperature solid-state method. By continuously adjusting the Dy/Tm ion concentrations, the white light emission with adjustable color temperature and color coordinate is achieved excited by the wavelength of 354 nm. The energy transfer mechanism between sensitized ions and activated ions is discussed with the help of fluorescence spectra and decay curve in details. Notably, different from other phosphors based on this host material, these prepared phosphors exhibit typical anomalous thermal quenching. It is very favorable for the devices working at high temperature. And this phenomenon may benefit from the high energy transfer efficiency at higher temperatures. The tunable white light and anomalous thermal quenching indicate that the studied material is a promising solid-state emitting phosphor for the white light-emitting diodes.

Polymethine cyanine dyes have a heterocyclic structure containing nitrogen at both ends of the polymethine chain. They have been extensively investigated in material sciences for numerous applications. The synthesis of cyanine dyes with various functional groups on the methine chain has attracted significant attention because it significantly alters the properties of the dye. However, few synthetic methods have been reported for directly introducing groups onto the methine chains of cyanine dyes. Ketone functional groups are essential in synthetic organic chemistry, biochemistry, and materials chemistry. However, there are no reports on the direct introduction of ketone groups into cyanine dyes. Trifluoroacetylation is performed on the methine chains of polymethine cyanine dyes. This is achieved by directly using anhydrous trifluoroacetic acid to synthesize trifluoroacetylated trimethine, pentamethine, and heptamethine cyanine dyes in good yields. Single-crystal X-ray structural analysis is performed to determine the substitution positions in the synthesized dyes. The results reveal that trifluoroacetylation of the methine chain shortens the maximum absorption wavelength and decreases the molar absorption coefficient in dichloromethane solution and poly(methyl methacrylate) film compared to an unsubstituted cyanine dye, and decreases the fluorescence quantum yield. This study highlights the unique properties of trifluoroacetylated polymethine cyanine dyes.

Functional switches exhibiting distinct functionalities responding to a specific stimulus are highly desirable for fabricating advanced devices with superior dynamic performances. Herein, a series of enaminitrile switches are explored as protofluorochromic entities by modulation of their structures, assisted by density functional theory calculations. The switches show high stabilities and exhibit reversible E/Z isomerization behavior, along with tunable fluorescence intensity in both protic and aprotic media. Switches based on 2-pyridyl- or 2-pyridylmethyl-containing N-components exhibit strong fluorescence in their protonated Z-configurations, compared to their phenyl/benzyl counterparts. This behavior can be attributed to variations in intramolecular charge transfer or excited-state intramolecular proton transfer effects. The Z-isomers are furthermore studied in their aggregated solid/film/dispersion states, resulting in notable aggregation-induced emission behavior.