Journal of Photochemistry and Photobiology C: Photochemistry Reviews最新文献

Mechano-responsive luminescence, or mechanochromic luminescence (MCL), is a type of luminescence that can be reversibly controlled by the addition of mechanical stimuli. Organic materials exhibiting MCL have been an ongoing area of development since the early 2000s, and the number of reports into such materials has been steadily increasing. While the majority of MCL systems rely on the brittle nature of organic crystalline solids, there is a growing interest in "flexible" organic crystals that exhibit mechanical bending or shape deformation owing to their elasticity/plasticity. Such non-destructive deformed crystals may exhibit a new type of MCL that can be controlled by the magnitude of the force stress. In this review, we describe MCL systems capable of the spontaneous recovery of changes in their luminescent properties in response to the loading/unloading of mechanical stress. We particularly focus on the MCL of flexible crystals based on the density gradient of molecular packing (i.e., elastic and plastic crystals) and an emerging system known as "superelastochromism,” which is based on spontaneously reversible crystal polymorphism. This emerging research area has the potential to play an important role in the promotion of next-generation soft crystals.

Luminescent lanthanide (Ln) complexes are attracted much attention because of their stable emission colors induced by the photo-antenna effect through the photo-excited energy transfer from aromatic ligands to Ln ions. Here, we will introduce some systems of luminescent Ln complexes with metastable states with the phase transition induced by water and other small molecules, the relative arrangement of hydrogel formation and Ln luminescence enhancement, and the diversity of the thin air-water interface. The energy donor levels in each system should be designed to sensitize Ln-luminescence with the consideration of media, interaction and assembling. Luminescence quenching of Ln complexes in water is a point that should be considered for the development of materials and for the purpose of bio-related materials. Then, the principle of the change in luminescence intensity by the effect of water molecules is described, and the estimation of a hydrated structure of the complex is estimated using the luminescence lifetimes in H₂O and D₂O. The molecular arrangement of these crystals changes under the vapor-stimuli, and the coloration and luminescence may be enhanced. Some interesting cases of luminescent Ln complexes with the crystal-to-crystal phase transitions will be introduced with the vapor adsorption. Hydrogels are mostly water by volume; a system in which Ln luminescence is maintained implies that Ln ions are placed in hydrophobic positions in self-assemblies with strong luminescence. The formation of thin films at the molecular level and their Ln luminescence properties are introduced. For example, when a monolayer of a surface-active Ln complex is formed at the air-water interface, the repeated accumulation of the flexible film forms a metastable structure with a regular structure different from that of a crystal, and no water is incorporated into the film. These can not only derive circularly or linearly polarized light, but also take in other molecules and change the emission. Finally, we will suggest the prospects for the development of Ln complexes.

This paper describes overview of electrofluorochromism, which is a phenomenon that controls photoluminescence through a change in the redox states of functional molecules, metal complexes, polymeric films, etc. Electrofluorochromic materials are considered prospective innovative materials because they can convert electrical input into intuitive visual signals. This field opens novel systems by combining absorption, reflection, and luminescence properties, leading to high contrast, night and day visibility, low-cost displays, and various sensing applications. The former sections provided a short overview of the electrofluorochromic phenomena and observation setups. The electrofluorochromic reactions and devices synchronized with the absorption change based on the electrochemical reaction we reported were also reviewed.

Semiconductor materials containing bismuth have attracted the attention of researchers over the past several decades, as a result of their high photocatalytic activity in various reactions and/or high efficiency in their photoelectric conversion of solar energy. This interest originated from the observations that bismuth-containing semiconductors have a sufficiently small bandgap, which makes them sensitive to radiation in the visible spectral range; thus, visible-light-active materials. Among the various bismuth-containing semiconductor materials, the bismuthates of alkaline earth metals are distinguished and describe into separate groups. This article reviews research on the known methods of obtaining bismuthates of various alkaline earth metals (magnesium, calcium, strontium, and barium), and further analyzes their composition, structure, and visible-light-active photocatalytic activity.

Visible-light photocatalysis offers unique opportunities to achieve smooth and clean functionalization of organic compounds by unlocking site-specific reactivities, generally under mild reaction conditions. This review offers a critical assessment of current literature, pointing out the recent developments and potential applications in the field of photocatalysis as well as its utilization in the field of organic synthesis for expected future progress.

Circularly polarized (CP) light, as a special form of polarized light, demonstrates potential application prospects in future displays and optoelectronic technologies. Circularly polarized luminescence (CPL) from chiral chromophores is an ideal method to directly generate CP light, but how to design efficient emitters is always a perplexing problem. Among various chiral materials, CPL materials with axial chirality can provide us with clear structural parameters and information to further explore the structure-activity relationship. Herein, we systematically summarize the development status of axially chiral compounds with CPL properties from two aspects of photoluminescence and electroluminescence, covering metal complexes, polymers, supramolecular assemblies, simple organic molecules, and liquid crystals systems. In addition, we initially explore the relationship between CPL performance and axially chiral configuration, and the current challenges and opportunities in this vibrant field are also discussed.

Photodynamic therapy (PDT) and photodynamic antimicrobial chemotherapy (PACT) combine light and photosensitizers to treat cancers and microbial infections, respectively. In PACT, the excitation of a photosensitizer drug with appropriate light generates reactive oxygen species (ROS) that kill pathogens in the proximity of the drug. PACT has considerably advanced with new light sources, biocompatible photosensitizers, bioconjugate methods, and efficient ROS production. The PACT technology has evolved to compete with or replace antibiotics, reducing the burden of antibiotic resistance. This review updates recent advances in PACT, with special references to light sources, photosensitizers, and emerging applications to microbial infestations. We also discuss PACT applied to COVID-19 causing SARS-CoV-2 treatment and disinfecting food materials and water. Finally, we discuss the pathogen selectivity and efficiency of PACT.

Hydrogen plays an important role in developing a clean and sustainable future energy scenario. Substantial efforts to produce green hydrogen from water splitting, biomass and hydrogen sulfide (H₂S) have been made in recent years. H₂S, naturally occurring or generated in fuel gas processing and industrial wastewater treatment, can be split into hydrogen and sulfur via photocatalysis. Although it is not as widely used as water splitting for green hydrogen production, this process is considered to be an appropriate and sustainable way to meet the future energy demands, adding value to H₂S. Therefore, it is essential to understand how to improve the solar light utilization and splitting efficiency of H₂S based on the existing technology and materials. Along with that effort, molecular modeling and theoretical calculations are indispensable tools to provide guidance to effectively design photocatalysts for improving hydrogen generation efficiency. In this review, we summarize the published work on H₂S photocatalysis modeling and illustrate the use of different computational methods to gain more in-depth insight into the reaction mechanisms and processes. Moreover, an overview of quantum mechanical and molecular simulation approaches combined with other modeling techniques, relevant to material science and catalysis design and applicable to H₂S splitting is also presented. Challenges and future directions for developing H₂S splitting photocatalysts are highlighted in this contribution, which is intended to inspire further simulation developments and experiments for H₂S splitting, tailoring photocatalysts design towards highly efficient hydrogen production.