A New Synthetic Approach for Polybenzoxazole and Light-Induced Fluorescent Patterning on Its Film

Reticular framework materials for photocatalytic organic reactions

Photocatalytic organic reactions, harvesting solar energy to produce high value-added organic chemicals, have attracted increasing attention as a sustainable approach to address the global energy crisis and environmental issues. Reticular framework materials, including metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), are widely considered as promising candidates for photocatalysis owing to their high crystallinity, tailorable pore environment and extensive structural diversity. Although the design and synthesis of MOFs and COFs have been intensively developed in the last 20 years, their applications in photocatalytic organic transformations are still in the preliminary stage, making their systematic summary necessary. Thus, this review aims to provide a comprehensive understanding and useful guidelines for the exploration of suitable MOF and COF photocatalysts towards appropriate photocatalytic organic reactions. The commonly used reactions are categorized to facilitate the identification of suitable reaction types. From a practical viewpoint, the fundamentals of experimental design, including active species, performance evaluation and external reaction conditions, are discussed in detail for easy experimentation. Furthermore, the latest advances in photocatalytic organic reactions of MOFs and COFs, including their composites, are comprehensively summarized according to the actual active sites, together with the discussion of their structure-property relationship. We believe that this study will be helpful for researchers to design novel reticular framework photocatalysts for various organic synthetic applications.

2-Phenylbenzoxazole derivatives: a family of robust emitters of solid-state fluorescence

In addition to thermal, chemical and photochemical stability, the 2-phenylbenzoxazole fragment exhibits attractive emission properties in the solid state, thus leading to highly photoluminescent materials and sensors.

Media with photoinduced irreversible fluorescence

The development of light-sensitive media based on organic, mostly heterocyclic compounds that have no fluorescence in their initial form but provide fluorescent photoproducts formation is considered in this review. Materials with photoinduced irreversible fluorescence appear to be the most promising in the design of recording media for 3D archive optical memory. Photoactivatable fluorophores are also of interest for use in cell biology.

Conjugated poly(fluorene-quinoxaline) for fluorescence imaging and chemical detection of nerve agents with its paper-based strip

Conjugated polymer of poly(fluorene-co-quinoxaline) was synthesized via Suzuki coupling polymerization. The emission color of the polymer can be tuned depending on the concentration of the polymer in solution. A low-energy bandgap is observed both in the concentrated solution and in the solid state, caused by aggregation of the polymer chains, resulting in long wavelength emission from the quinoxaline moiety, while short wavelength emission can be seen in diluted, well-dissolved solution. The presence of quinoxaline units enables us to demonstrate fluorescence switching and imaging. Paper-based strips containing the polymer are prepared via simple immersion of filter paper in the polymer solution for practical use in the detection of nerve agents. The emission of the paper-based strip is quenched upon exposure to diethyl chlorophosphate (DCP), a nerve agent simulant, and the initial emission intensity can be almost restored by treatment with aqueous sodium hydroxide solution, making a possible reversible paper-based sensor.

Luminescent materials containing multiple benzoxaphosphole units

A series of bisbenzoxaphospholes and a trisbenzoxaphosphole have been prepared and characterized.

Creating bicolor patterns via selective photobleaching with a single dye species

Bicolor fluorescent pattern in thin polymer film is fabricated via a photobleaching process. Dye molecules exhibit monomer emission when they are dispersed inside the polymer and aggregate emission when they are on the surface of the polymer. Thus, a mixed emission of monomer and aggregate can be obtained by evaporating a single dye species on the polymer film. Bicolor pattern in thin polymer film is readily formed by selective photobleaching. This process is particularly attractive for the fabrication of bicolor patterns on flat substrates using a single dye species, which is of potential applications in photonic/electronic devices.

Newly Synthesized Branch-type Aromatic Oxadiazole Polymer and Binary Fluorescence Patterning on its Film

Aromatic side-chain oxadiazole polymer linked with 9,9'-dioctylfluorene was successfully synthesized via Suzuki coupling reaction. Hydroxyphenyl group was attached in the 2-position of the oxadiazole unit in the polymer side chain to control the optical properties of the polymer. We confirmed the presence of the t-butoxycarbonyl group on the hydroxyl group using thermogravimetric analysis, which was incorporated to avoid side reaction during polymerization. We also performed the simple and easy fabrication method for the dual fluorescence image using photochemical cleavage of the t-butoxycarbonyl group from the polymer to induce fluorescence color changes before and after UV irradiation.