Studies on the photochemical stabilities of some fluorescent films based on pyrene and pyrenyl derivatives

Coordination-Driven Self-Assembled Metallacycles Incorporating Pyrene: Fluorescence Mutability, Tunability, and Aromatic Amine Sensing

“…The fluorescence intensity of the film decreased by only ∼5% after 9 h of continuous light irritation (Figure S29). In contrast, the emission of the pyrene-based film reaches almost zero due to complete photobleaching, as reported earlier, 68 suggesting that the metallacycle is photochemically suitable for sensing.…”

Dual-Phase Emission AIEgen with ICT Properties for VOC Chromic Sensing

“…25,26 In addition, the assemblies of pyrene that exhibit bad photochemical stability while being immobilized on the substrate surface resulted from the photobleaching effect. 27,28 Therefore, it remains a great challenge to design and synthesize photochemically stable pyrene-based fluorophores that could present robust luminescence both in solutions and in the solid state for their applications in fluorescent sensors. 29−31 o-Carborane is a three-dimensional polyhedral boron cluster with ease of functionalization and outstanding thermal and chemical stability.…”

“…Sensors are widely employed in daily life, such as electric sensors, − magnetic sensors, , mass sensors, , optical sensors, , etc. Among them, fluorescent sensors, which are based on changes of the first excited electronic state of a molecule responding to the surrounding microenvironment, have drawn much attention due to their advantages including high sensitivity, high specificity, immunity to light scattering, and ease of operation. − In a fluorescent sensor, luminogens are of vital importance since they play the role of probes or indicators to interact with the analyte. , For example, pyrene consisting of planar and polycyclic π-conjugated frameworks possesses salient photophysical properties such as high fluorescence quantum yield, long fluorescence lifetime, a great tendency to form an excimer, and high polarity dependence of its monomer emission, with great potential for the construction of fruitful fluorescent sensors. − Nevertheless, their applications are often hampered by the aggregation-caused quenching (ACQ) effect, which was first proposed by Förster and Kasper. , Traditional organic luminogens like pyrene show high luminescence quantum yields in dilute solutions, while they are weakened or even totally quenched in concentrated solutions or in the solid state due to the formation of detrimental aggregates that facilitate exciton interactions and nonradiative pathways, commonly defined as the ACQ effect. , In addition, the assemblies of pyrene that exhibit bad photochemical stability while being immobilized on the substrate surface resulted from the photobleaching effect. , Therefore, it remains a great challenge to design and synthesize photochemically stable pyrene-based fluorophores that could present robust luminescence both in solutions and in the solid state for their applications in fluorescent sensors. − …”

High-Performance Sensing of Formic Acid Vapor Enabled by a Newly Developed Nanofilm-Based Fluorescent Sensor

“…For preferable adlayer structures, a variety of film fabrication strategies have been developed, such as the strategies of self-assembled monolayer (SAM), , molecular gel, drop-casting, , etc. − Each type of as-fabricated film has its own merits; for example, SAM films usually show high sensitivity because of the efficient interaction between the analyte and sensing unit in a pseudo-molecular-thick adlayer; most of the films made by the molecular gel strategy exhibit higher photochemical stability owing to the fact that the sensing units exist in a semi-solidified state in the gel networks. However, new strategies for sensing film fabrication are still needed as the strategies documented have their own shortcomings. − For example, the photochemical stability of SAM films is generally not good enough, and the thickness of films from molecular gel or drop-casting strategies is hard to control, resulting in a declined performance over time and inconsistency in production of the films. With the merits in super-porosity, uniform microstructure and designable structure, two-dimensional (2D) nanofilms have been widely used in molecular separation, , crystal engineering, sensing, , etc. , Therefore, it is expected that 2D nanofilms would bring at least three advantages for film-based sensing: (1) superior porosity of the nanofilm must be favorable for mass transfer of the analyte within the adlayer, laying a solid foundation for fast and reversible detection; (2) uniform structure of the nanofilm not only guarantees uniform distribution of the sensing units within the film adlayer but also provides the nanofilm with additional selectivity owing to the size exclusion effect; (3) module structure and interfacial fabrication provide the possibility of not only fine design of the chemical structure of the nanofilms but also fine control of their thickness, which can both be used for optimization of the sensing performance of the nanofilms.…”