ChemPhotoChem最新文献

The determination of the biodistribution of cyclodextrin-based (nano)materials represents a critical point for their development and in vivo use as drug carriers and gene-delivery systems. In this work, we report the design and preparation of a Eu(III)-based emissive probe based on a new adamantyl-appended β-diketone. This probe has favorable emission and structural features, as it is endowed with a long lifetime (280 µs). Also, it is able to form a stable supramolecular inclusion complex with virtually any cyclodextrin-based systems. With such an emissive probe, time-resolved fluorescence imaging techniques could be exploited to obtain images with higher contrast and hence enhanced quality, allowing one to follow the fate of cyclodextrin-based delivery systems in complex biological media, such as cells and tissues.

Zinc oxide (ZnO) has garnered significant attention as a promising photoanode material for photoelectrochemical (PEC) water splitting. However, its photoelectrocatalytic performance is hindered by a wide bandgap and fast recombination of photogenerated electron–hole pairs. In this study, ZnO/CdS heterostructured photoanodes were fabricated using a combination of atomic layer deposition, hydrothermal synthesis, and successive ionic layer adsorption and reaction (SILAR) techniques. Compared with the conventional single-step hydrothermal method, a secondary hydrothermal treatment significantly improved the PEC performance of the ZnO/CdS photoanodes. Under standard simulated solar irradiation (AM 1.5 G, 100 mW/cm²), the optimized ZnO/CdS photoanode achieved a remarkable photocurrent density of 9.46 mA/cm² (at 1.23 V vs. RHE) and a photoconversion efficiency of 4.61%, which is among the highest values reported for pristine ZnO/CdS-based photoanodes. Comprehensive microstructural characterization and electrochemical analyses revealed that the charge carrier migration mechanism in the as-prepared ZnO/CdS system follows a Z-scheme pathway. Furthermore, the secondary hydrothermal process facilitated the controlled growth of secondary ZnO NRs, which increased the electrochemically active surface area and promoted efficient charge transport. These structural and electronic improvements collectively led to enhanced photocurrent density and photoconversion efficiency. This study presents a novel and effective approach for enhancing the PEC performance of semiconductor-based photoanodes.

This study addresses the anomalous fluorescence of a rhodanine-based organic dye of interest for nonlinear optical applications. At room temperature, the dye exhibits weak fluorescence, while spectra collected in glassy 2Me-THF at 77 K show a surprising fluorescence intensity increase by several orders of magnitude with respect to room temperature. Moreover, a pronounced dependence of the fluorescence quantum yield on the excitation wavelength is observed, indicating a breakdown of Vavilov's rule, a corollary of Kasha's rule, which states that the fluorescence quantum yield is independent of the excitation energy. Quantum chemical calculations demonstrate the presence of a bright ππ* excited state that lies very close in energy to a dark nπ* state. The subtle interplay between these two excited states with different natures is responsible for the intriguing spectral behavior of the dye. Specifically, experimental results are rationalized in terms of a population branching between the two excited states, which can be tuned upon varying the temperature or the excitation energy.

Luminescent blue phase liquid crystal (LBPLC) is an important material used in the construction of optoelectronic devices, with broad application prospects in the fields of lasers, display devices, and smart materials. Studying the fluorescence regulation of LBPLCs is crucial for further utilization and enhancement of its optoelectronic properties. This review systematically summarizes the recent advancements in LBPLC, categorizing them into two parts: small-molecule BPLC and BPLC polymer (BPLCP). Among them, small-molecule LBPLC is further divided into three types based on modulating methods: photoswitch-doped, luminescent dye-doped and nanoparticle-doped, while BPLCP is divided into polymer-stabilized BPLCs (PS-BPLC) and BPLC elastomers (BPLCEs). This review also outlines fluorescence regulation mechanisms, highlights diverse applications of stimuli-responsive LBPLCs, and discusses current challenges and future perspectives. This review aims to contribute to the interest inspiration and future research development of LBPLC.

Inspired by the beauty of natural motions presented in biological systems, synthetic photoresponsive soft materials were developed to mimic natural movements. Recent advancements of supramolecular soft robotic systems can functionalize the system with external stimuli-responsiveness, e.g., light, heat, pH, and ions, but high structural arrangements are generally required. A supramolecular soft robotic system of spiropyran amphiphiles was reported previously, which enables macroscopic motions without high macroscopic structural requirements (high orientation order and structural uniformity). Herein, subtle modifications of the molecular design (i.e., different chain-lengths of the alkyl-linker) enable adjustments of packing parameters of spiropyran amphiphiles between open- and closed-isomers. Upon macroscopic soft scaffolds formed by a shear-flow method, the scaffolds with shorter chain-lengths of the alkyl-linker of spiropyran amphiphiles sustain photoactuations, while no photoactuation is observed with longer chain-lengths of the alkyl-linker of spiropyran amphiphiles.

We demonstrate for the first time that nonstoichiometric quaternary Ag–In–Zn–S semiconductor nanocrystals, which do not contain toxic elements, can be used as efficient photocatalysts in photoinduced electron transfer reversible addition-fragmentation chain transfer (PET-RAFT) polymerization. Careful tuning of their composition yielded two types of alloyed nanoparticles, namely emitting red and green light. The PET-RAFT polymerizations were carried out at room temperature, under UV, blue and green illuminations. Chain transfer agents such as 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid (CPADB) or 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid (CDTPA) were added to a dispersion of nanocrystals, completed by introduction of triethylamine (TEA). Nanocrystals/RAFT reagent/TEA systems, in the presence of green light, turned out to be very efficient, especially in the polymerizations of “model” monomers such as methyl methacrylate (MMA) and N,N-dimethyl acrylamide (DMA). In particular, hydrophobic nanocrystals in combination with the CDTPA/TEA, under green radiation initiated photocontrolled polymerization of MMA yielding PMMA whose molecular mass could be precisely controlled, simply by changing the RAFT reagent concentration. The same set of reagents was used for the MMA photopolymerization under the sunlight at ambient (laboratory) conditions resulting in PMMA of M_n = 45.4 kDa and Ð = 1.21.

A novel fluorophore (E)-4-(2-(2-methoxynaphthalen-1-yl)vinyl)-1-methylpyridin-1-ium iodide (MVMI) was investigated by spectrodynamic experiments and quantum chemical calculations. Our studies indicated that MVMI serves as a unique example of an intramolecular charge transfer (ICT) probe existing in an equilibrium between the twisted and the planar forms with respect to the donor and acceptor units. Excitation of the twisted form leads to emission from the twisted excited state (T*) with emission from the planar excited state (P*) formed by a twisting from T* to P*. The excitation of the planar form leads to ICT-type single emission from P*.The current report is of particular importance as the photobehaviour of MVMI is totally reversed from conventional ICT probes, obeying the twisted intramolecular charge transfer model, where an otherwise planar fluorophore undergoes twisting in the excited state to furnish a transient twisted excited state, the latter deemed as the origin of the CT emission band. The current results shall act as a cornerstone to stabilize and tune unusual, twisted states in the ground state, as well as to extract combined emission signals from locally excited and ICT states.

The vibronic structure of the UV–visible absorption spectra of linear perylene diimide oligomers is simulated using time-dependent density functional theory and compared to experiment. The spectra were calculated using the B3LYP, B3LYP-35, M05-2X, and CAM-B3LYP exchange–correlation (XC) functionals, while accounting for solvent effects with the integral equation formalism polarizable continuum model. Two computational approaches for vibronic structure simulations, the gradient and geometry methods, were evaluated for their ability to reproduce experimental spectral features of these aggregates. While both methods retrieve the expected J-like aggregate behavior for the monomer and the dimer spectra, significant challenges emerge for the trimer. For the former, when combined with the CAM-B3LYP XC functional, the gradient method consistently agrees with experiment, suggesting that it provides reliable extrapolations of the potential energy surface, leading to physically accurate minima. Further dimer calculations confirm that obtaining accurate vibronic spectra depends on correctly capturing whether the electronic excitation and geometry changes are spread across the entire aggregate or confined to individual units.

Utilizing a fused isoindoline nitroxide-styrylpyrene system (StyPyNO), this work presents an interrogation into the effects of the radical spin on the [2+2] photocycloaddition of styrlpyrene and explores the photoswitchability of the system. Through irradiation with both broadband lamps and laser light sources, the influence of the nitroxide moiety on photoreactivity was analyzed and compared with both styryl pyrene and diamagnetic controls. The presence of the radical spin prevented the intermolecular [2+2] photocycloaddition observed from the control systems, instead allowing for a trans–cis photoisomerism under identical 420 nm irradiation conditions. Studies into the triplet lifetimes of the radical containing and control systems allowed for deeper understanding around the mechanism of photoreactivity. The system explored presents a means of controlling photo reaction progression not only via wavelength of irradiation, but also via the presence or removal of the unpaired electron within the nitroxide moiety. This in turn presents the potential for a dual gated chemical/photoswitchable system.

Dye-sensitized solar cells (DSSCs) are well known as the current emerging and promising photovoltaic devices due to their cost-effectiveness and high performance under diffused light conditions. The efficiency of DSSCs is primarily characterized by the structural and electronic features of the photoanode. This study focuses on optimizing the hydrothermal synthesis of TiO₂ nanorods (NRs) on fluorine-doped tin oxide (FTO) substrate by varying the reaction time from 4 to 9 h. The 8 h synthesis duration produced highly aligned TiO₂ NRs exhibiting superior crystallinity, reduced defect density, and optimal bandgap (∼2.98 eV). The corresponding DSSCs achieved an efficiency of 0.97%, outperforming shorter or longer synthesis times due to enhanced charge transport and minimized recombination. These results demonstrate that precise control of hydrothermal time is key for fabricating efficient, natural dye-based DSSCs.