ChemPhotoChem最新文献

Metastable-state photoacid (mPAH) has become a common tool for controlling and driving chemical processes with light. mPAHs with fast reverse reactions are desirable for precise temporal control or generating quick pulses of proton concentration. In this work, different approaches towards fast reversing mPAHs are studied. Experimental and computational results showed that stabilizing the charge–transfer intermediate is an effective way to increase the rate. A novel mPAH with a reverse reaction ≈500 times faster than the most used mPAH in methanol is developed. Another water-soluble mPAH showed a reverse reaction with a rate constant of 7.8 s⁻¹, which is the fastest ever reported. The half-life of the acidic state is calculated to be 89 ms, which allowed to demonstrate sub-second switching using this mPAH.

Beginning in 2017, the groups of Nicewicz, Burton, Lambert, and others have reported an ever-widening array of formally redox neutral nucleophilic aromatic substitution (S_NAr) reactions that proceed via an aromatic radical cation intermediate. However, the roots of this reaction extend far back more than 50 years to foundational work by Nyberg, Kochi, Cornelisse, and Eberson. Unfortunately, much of this early precedent appears to have been overlooked, despite the fact that it offers many potentially useful mechanistic insights into the more modern transformations. Additionally, it is found that this early work has not previously been reviewed in the unified context of nucleophilic aromatic substitution. In this review, a glimpse into the past is provided before discussing the exciting developments of the last decade in this area. The review is concluded with an overview of some of the potential growth opportunities that remain.

Cancer remains a major global health challenge, necessitating the development of alternative therapies that minimize side effects and overcome drug resistance associated with conventional treatments. In this study, it reports the synthesis and characterization of a series of platinum(II) complexes based on azadipyrromethene (ADPM) ligands as novel photosensitizers for photodynamic therapy (PDT). These complexes are designed to enhance light absorption and photochemical activity through the incorporation of heavy atoms. Their photophysical properties—including absorption spectra, fluorescence emission, and singlet oxygen generation efficiency—are systematically investigated. The complexes exhibited strong absorption in the visible region and high singlet oxygen yields, indicating their suitability for PDT applications. In vitro assays using several cancer cell lines demonstrate low cytotoxicity under dark conditions, whereas light activation induces a significant cytotoxic response. Flow cytometry analysis further confirms that the treatment induces apoptotic cell death. These effects were found to be both light- and concentration-dependent. Overall, this study's results demonstrate the potential of these platinum–ADPM complexes as effective and selective PDT agents, offering a promising strategy for the development of safer and more targeted cancer therapies.

In this study, it is investigated how the N-substitution pattern modulates the excited-state intramolecular proton transfer (ESIPT) in polysubstituted imidazoles, a class of compounds with promising photophysical properties. The selective use of a single isomer, either enol or keto, has emerged as a valuable strategy in developing new functional molecules. Using a combination of experimental and theoretical methods, it is addressed how N-alkyl substituents in combination with a 2-(methoxy)phenyl group significantly influence the conformation and stabilization of enol and keto tautomers involved in the ESIPT process. Single-crystal X-ray diffraction reveals a clear influence on the dihedral angle involved in the ESIPT pathway in the crystalline solid state, while (time-dependent) density functional theory reveals the importance of conformational flexibility and substituent π-donation in shaping the excited-state potential energy surface to access a regime of tunable ESIPT. Supported by steady-state solvent-polarity-dependent emission, aggregation-induced emission, and viscosity-dependent emission, an enhanced emission correlated with the stabilization of a specific isomer is demonstrated.

The advent of photoredox catalysis has created a massive buzz in the field of synthetic organic chemistry. As the photoredox process is invariably mediated by the transfer of single electrons, species such as radical cations are inevitable. These species have orcastracized various synthetic transformations that otherwise would have been difficult to achieve. One such class of transformations is the cycloaddition reaction. For driving such reactions, it is often necessary that the radical and cation sites are present on different atoms, in other words, are distal or “distonic” in nature. In the present review, the development of distonic radical cations has been brought forth and their tactical exploitation over the years for the purpose of cycloaddition reactions in the visible-light realm. The entirety of the manuscript has been divided into categories discussing [2 + 2], [3 + 2], and [4 + 2] cycloadditions. In each case, the distonic radical cation that drives the cycloaddition has been highlighted along with necessary discussions, providing readers with an opportunity to appreciate the power of these wonderful intermediates.

This study reports the synthesis of γ-Al₂O₃ supported CuO (C-AlO14) material via impregnation technique. The synthesized C-AlO14 photocatalyst successfully degraded crystal violet (CV) dye via photoactivation of peroxymonosulfate (PMS). The synthesized photocatalysts are thoroughly examined using a variety of techniques, including energy dispersive X-ray spectroscopy, scanning electron microscopy, X-ray diffraction analysis, and fourier transform infrared spectroscopy. The Tauc plots indicated the band gap energy of C-AlO14 was 2.1 eV compared to 1.67 eV for CuO and 3.3 eV for γ-Al₂O. The results indicated that CV (10.0 mg L⁻¹) is almost entirely eliminated (99%) by using C-AlO14 (30 mg) in the presence of PMS (2.0 mM) at pH 6.8 under 30 min of UV irradiation. Scavenger studies indicate that the reaction system produces SO₄^•−, ^•OH, h⁺, and O₂^•−. Accordingly, detailed charge transfer pathway mechanism is explored for UV/C-AlO14/PMS system. Furthermore, degradation intermediates of CV are identified, and subsequently degradation pathways are proposed. Ecological structure activity relationships analysis indicated that UV/C-AlO14/PMS process degrades organic contaminants by environmentally safe route.

Multiresonant thermally activated delayed fluorescence (MR-TADF) materials have emerged as next-generation OLED emitters owing to their narrowband emission, high color purity, and potential for 100% exciton utilization. Among the various MR-TADF scaffolds, carbonyl/nitrogen-based, quinolino[3,2,1-de]acridine-5,9-dione (QAO) cores have attracted significant attention due to their modularity and electronic tunability. This review article presents a systematic analysis of recent advancements in QAO-based emitters, categorized into three molecular design strategies: core locking, core substitution, and core extension. Core locking enhances rigidity, minimizes vibrational loss, and narrows emission profiles critically mandated by blue-emitting MR-TADF systems. Substitution at key positions enables fine control over emission wavelength, ΔE_ST, and photoluminescence quantum yield (Φ_PL). Core extension via π-conjugation elongation or fused aromatic units leads to improved device efficiencies and diverse emission colors, including green and deep-blue electroluminescence. Collectively, these strategies have produced emitters with Φ_PL exceeding 90%, EQEs above 30%, and full-width half maximums as low as 20 nm. We conclude by highlighting current limitations, including RISC bottlenecks, doping concentration effects, and synthetic challenges, while proposing design pathways toward next-generation multifunctional, solution-processable, and chiral MR-TADF materials. This review article provides a roadmap for advancing carbonyl-nitrogen based MR-TADF emitters toward high-performance OLED technologies.

The development of photosensitizers (PSs) with extended triplet-state lifetimes, efficient reactive oxygen species (ROS) generation, organelle-specific targeting, good water solubility, and high photostability, is essential for advancing photodynamic therapy (PDT). Although molecular aggregation holds promise for designing organic nano-PSs with enhanced therapeutic effects, controlling dye aggregation remains a significant challenge. In this study, we present a simple yet robust synthetic strategy for developing heavy-atom-free PSs with intramolecular charge transfer (ICT)-coupled aggregation-induced emission (AIE) properties. These PSs feature donor–acceptor (D–A) structures, namely Lyso-Naphth-AIE and Butyl-Naphth-AIE, which exhibit high photostability and negligible dark toxicity. Upon light irradiation, these AIE systems efficiently generate ROS via both Type I and II mechanisms. By incorporating p-methoxytriphenylamine (MeO-TPA) as a rotor unit, we enhanced AIE and promoted twisted intramolecular charge transfer (TICT), resulting in improved near-infrared luminescence in the aggregated state. Notably, the Lyso-Naphth-AIE nano-PSs demonstrated effective lysosome-targeting and light-triggered intracellular ROS production, leading to apoptosis, in cancer cells. This work establishes a new approach for designing multifunctional AIE PSs that enable imaging-guided PDT.

It is known that peri-aryloxyquinones based on 5,12-naphthacenequinone (hereinafter referred to as PANQs) undergo multiple photoswitching between the initial state and thermally stable ana-quinone. However, no nuclear magnetic resonance (NMR) studies of their photochromic performance have been reported previously. In this work, a series of 11 new PANQs are prepared, and their light-induced reaction is investigated using NMR spectroscopy for the first time. The results support early observations regarding the fatigue resistance as well as thermal and chemical stability of the photoisomers of peri-aryloxyquinones based on naphthacenequinone.

The rational design of heterostructured photocatalysts integrating efficient charge separation and CO₂ enrichment remains a key challenge in artificial photosynthesis. Herein, a ZIF-8/TiO₂ heterojunction photocatalyst is reported, fabricated via gas-phase deposition and hydrothermal methods. The composite combines ZIF-8's high CO₂ adsorption capacity with TiO₂'s photocatalytic activity, forming a chemically bonded Type-II interfacial heterojunction that promotes directional charge separation and suppresses carrier recombination. Synergy between ZIF-8's porous CO₂ enriching framework and heterojunction-driven charge transfer enhances CO₂ photoreduction performance: under simulated sunlight, it achieves CH₄ and CO evolution rates of 1.30 and 4.22 μmol g⁻¹h⁻¹, respectively. This work provides a scalable paradigm for integrating CO₂ capture with semiconductor heterointerfaces in photocatalytic systems.