ChemPhotoChem最新文献

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.

Perovskite solar cells (PSCs) have rapidly progressed over the past few years, with efficiencies approaching 27%. However, the formation of detrimental defects resulting from rapid crystallization that induce the nonradiative recombination and low carrier mobility hinders further commercialization development. The use of passivators to reduce the defects in perovskite materials has been demonstrated to be an effective approach for enhancing the photovoltaic performance and long-term stability of PSCs. Screening strategy of passivators have received increasing attention as the library of chemical passivators consistently expand. First, this concept discusses the main types of defect in perovskite materials and reviews their properties. We examine the deleterious impact of defects on device efficiency and highlight the passivation mechanism of Lewis base molecules. Second, this concept also provides an overview of passivator screening strategies, including donor–acceptor (D-A) pair regulatory strategies and engineering spatial conformation. Finally, we propose screening direction for future research, which, in our view, will be crucial for unlocking the full potential of PSCs using the concept of defect passivation.

Carbon nanodots (CNDs) have attracted growing interest due to their potential applications in sensing, imaging, and optically controlled bio-applications. Herein, the covalent functionalization of citric acid/ethylenediamine-based CNDs with a tetra-ortho-fluoro-azobenzene derivative (F-Azo) is presented. This approach aims to integrate the intrinsic photoluminescence of CNDs with the reversible photoisomerization properties of F-Azos triggered by visible light. The CND-F-Azo hybrids are synthesized via a terminal carboxylic acid group located on the F-Azo, which can be attached via amide coupling to surface-accessible amines on the CNDs. The structural and optical characterization of the resulting hybrid material is performed using a variety of analytical and spectroscopic techniques, as well as computational analyses supporting the covalent linking between the molecular and nanomaterial components and the interactions existing between them. In order to assess the impact of functionalization on physicochemical properties, the hybrid is further analyzed with respect to zeta potential, lipophilicity, and cell viability using HEK-293 cell assays. To assess cellular uptake and intracellular localization, confocal fluorescence imaging is employed. This work contributes to the development of light-responsive nanomaterials with tailored surface properties, highlighting the potential of Azo-functionalized CNDs as multifunctional platforms for future in vitro and in vivo optostimulation applications.

Switchable intersystem crossing (sISC) is a novel concept in the design of functional dyes that enables dynamic modulation of fluorescence and triplet state formation in response to changes in the dye's environment. Unlike conventional dyes, where intersystem crossing and fluorescence rates are entirely determined by molecular structure, sISC dyes allow reversible switching between these functions based on external factors, such as solvent polarity. sISC can arise from various photophysical mechanisms involving charge–transfer states, whose energies are sensitive to the surrounding environment. Mechanisms such as thermally activated delayed fluorescence and spin–orbit charge transfer intersystem crossing can be employed to design sISC dyes. The ability to fine-tune photophysical processes without chemical modification of the dye's structure opens new possibilities for biomedical applications, including bioimaging, photodynamic therapy, and optogenetic control. This paper introduces the concept of sISC, provides key examples of dyes exhibiting this behavior, and discusses approaches for their design.

Chiral copolymer thin films show a strong chiroptical response, in the present study with values for the circular dichroism (CD) reaching up to 16,000 mdeg and a dissymmetry parameter, g_abs, of up to 0.7. This behavior renders these films highly attractive for optoelectronic applications, such as OLEDs with intrinsic circularly polarized emission. Such films of the achiral copolymer poly-[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (shortly, F8BT) blended with helicene-like chiral inducers are investigated. These films exhibit a unique sign inversion effect of the CD and the circularly polarized luminescence (CPL) signals as a function of film thickness (with a threshold of about 100 nm) and annealing temperature (with a threshold of about 150 °C). It is shown that structural reorganization of the chiral supramolecular phase is the most likely reason for this effect. Detailed measurements of the CPL spectra as a function of the detection angle underline the importance of detecting the emission at normal incidence to the polymer surface to avoid distortion of the CPL signal, which is otherwise identified by a bisignate CPL response at larger detection angles due to waveguide emission from the edge of the polymer film.

The long-lived radical R6G^•, derived from the cationic dye rhodamine 6G (R6G⁺) by reduction, is of growing interest in photoredox catalysis. This manuscript discusses three methods of its preparation in dimethylsulfoxide, highlighting spectral differences due to solvatochromism, co-solutes, and the basicity of the solution. Upon excitation, R6G^•* can release an electron to a substrate molecule or as a solvated electron, leading back to R6G⁺. However, a second reduction of R6G^• is not observed to be reversible here, decreasing the overall concentration of R6G^• and R6G⁺ with time. R6G⁺ can also be deprotonated to R6G1 under basic conditions, and even double deprotonation to R6G2⁻ is possible, though this may undergo irreversible reaction over time. Excitation of R6G1 leads to the formation of a photoproduct stable for seconds, which then reforms R6G1. If R6G^• is exposed to basic conditions in the presence of oxygen, it is oxidized to R6G⁺, which is then quickly deprotonated to yield R6G1 again. Hence, in basic solution, R6G1 is the predominant species, so that other light-induced reaction pathways than with R6G⁺ are accessible. It remains to be determined whether the photoproduct of R6G1 could be beneficial for a photocatalytic application under strongly basic conditions.

Dye-sensitized solar cells (DSSCs) have remained a promising alternative in photovoltaic technology due to their cost-effectiveness and adaptability to low-light conditions. Among the various sensitizers, subphthalocyanines (SubPcs) have emerged as potential candidates due to their nonflat structure, which reduces aggregation and increases solubility. However, their application in DSSCs remains poorly explored. In this study, four new SubPc dyes with different peripheral substituents are synthesized and characterized to evaluate their photovoltaic performance. The best-performing dye, SubPc 3, exhibits the most redshifted absorption spectrum and achieved a maximum efficiency of 1.69%. Photophysical analyses are conducted using transient absorption spectroscopy and intensity-modulated photovoltage/photocurrent spectroscopy (IMVS/IMPS). IMVS/IMPS measurements indicate a relatively stable electron population in the semiconductor, with an electron lifetime in the semiconductor significantly longer than the transport time, which leads to a satisfactory charge collection efficiency (η_cc = 0.83). However, ps-TAS analysis reveals efficiency losses due to competing geminate recombination (τ_grec = 1.264 µs) with the dye regeneration (τ_reg = 0.594 µs) at the origin of photogenerated current limitations. This study provides a basis for future research on SubPc sensitizers, highlighting the importance of mitigating recombination pathways to maximize light absorption and charge separation.

Subtle modification on chemical structures plays a key role in determining aggregate morphology and mechanofluorochromic (MFC) behaviors. Herein, aggregation-induced emission (AIE)-active tetraphenylethene-functionalized vinylogous-dicyano aryl derivatives with different of N-substituent groups (T-1: R=-H and T-M: R=-CH₃) have been designed and synthesized, and systematically investigated the effect of substituents on their aggregate morphology and MFC behavior. The single crystal X-ray analysis and density functional theory calculations illustrate that T-1 and T-M exhibit clear twisted spatial conformations and intramolecular charge transfer (ICT) characteristics. Meanwhile, T-1 and T-M show completely opposite directions of emission shifts after grinding. The T-1 exhibits obvious blue-shift (32 nm) trend without N-alkyl modification, while T-M shows red-shifted (26 nm) upon grinding. Moreover, the T-1 achieves blue-shifted MFC behaviors by amorphous states transition, and overcomes the limitations of conventionally ordered crystalline MFC materials. The phenomenons may be ascribable to mechano-induced short-range molecular order within the amorphous state. The powder X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry analysis confirm amorphous states transition process. The T-1 and T-M reveal that partial reversible opposite MFC properties, AIE characteristic, and N-alkyl modification play a functional role in tuning their MFC behaviors and morphology structural changes.

We report the synthesis and characterization of four luminescent soft salts (S1–S4), composed of ion-paired cyclometalated Pt(II) complexes featuring either pyridine- or pyrimidine-based ligands. These compounds were prepared via metathesis reactions between complementary cationic and anionic Pt(II) precursors and were fully characterized by NMR spectroscopy and electrospray ionization high-resolution mass spectrometry. Their photophysical and chromic properties were investigated, and their excited states were modeled using time-dependent density functional theory. In DMSO solution, the emission originates from the anionic fragment, with quantum yields reaching up to 0.69. In the solid state, a redshifted emission is observed, attributed to metal–metal-to-ligand charge transfer excited states formed between paired complexes. Soft salts bearing a pyrimidine-based anionic fragment exhibit aggregation-induced emission, whereas their pyridine-based analogs show aggregation-caused quenching in DMSO/water mixtures. Soft salts incorporating pyrimidine-based ligands display vapochromic and acid-responsive behavior, with emission shifts or quenching upon exposure to solvent or acid vapors; partial reversibility is achieved through grinding or treatment with ammonia. These results underscore the tunability of photophysical properties through strategic azaheterocyclic ligand design and aggregation control.