Effects of the Surface Charge Density of Clay Minerals on Surface-Fixation Induced Emission of Acridinium Derivatives

Abstract

Surface-fixation induced emission is a fluorescence enhancement phenomenon, which is expressed when dye molecules satisfy a specific adsorption condition on the anionic clay surface. The photophysical behaviors of two types of cationic acridinium derivatives [10-methylacridinium perchlorate (Acr + ) and 10-methyl-9-phenylacridinium perchlorate (PhAcr + )] on the synthetic saponites with different anionic charge densities were investigated. Under the suitable conditions, the fluorescence quantum yield (Φ f ) of PhAcr + was enhanced 22.3 times by the complex formation with saponite compared to that in water without saponite. As the inter-negative charge distance of saponite increased from 1.04 to 1.54 nm, the Φ f of PhAcr + increased 1.25 times. In addition, the increase in the negative charge distance caused the increase in the integral value of the extinction coefficient and the radiative deactivation rate constant ( k f ) and the decrease in the nonradiative deactivation rate constant. It should be noted that the 2.3 times increase in k f is the highest among the reported values for the effect of clay. From these results, it was concluded that the photophysical properties of dyes can be modulated by changing the charge density of clay minerals.

Adsorption of Dye Molecules and Its Potential for the Development of Photoactive Hybrid Materials Based on Layered Silicates

“…Therefore, the final impact of the adsorption of a fluorophore molecule on the surface of a layered silicate on Φ f would depend on the balance between the mentioned effects . Specific examples of AdIE include various types of dyes such as 10-methyl-9-phenylacridinium, or five different stilbazolium derivatives . However, in some cases, the adsorption of a molecule on the surface only affects one of the two possible relaxation mechanisms.…”

Crystal Phase and Morphology-Controlled Synthesis of Tungsten Oxide Nanostructures for Remarkably Ultrafast Adsorption and Separation of Organic Dyes

“…Among numerous chemical, physical, and biological wastewater treatment techniques for reducing the contaminant's concentration to an acceptable level, 5,6 adsorption is one of the most common and convenient methods because of its ease of operation, flexibility, high efficiency, low cost, and easy regeneration. 7,8 So far, most adsorbents are mainly porous materials, including activated carbon, 9,10 zeolites, 11,12 clay minerals, 13 biowaste, 14 siliceous, 15,16 and polymeric materials. 17,18 These materials have excellent adsorption capacity for organic dyes due to their porous structures and high surface area.…”

“…So far, most adsorbents are mainly porous materials, including activated carbon, , zeolites, , clay minerals, biowaste, siliceous, , and polymeric materials. , These materials have excellent adsorption capacity for organic dyes due to their porous structures and high surface area. However, the adsorption rate is often slow. ,,, Therefore, exploring new adsorbent materials demonstrating high adsorption rates at room temperature would primarily save treatment time and subsequent costs involved, improving the overall efficiency of the process.…”

Emission enhancement in twisted pyridyl salt using a montmorillonite nanoclay by the intercalation and surface-fixation processes

“…Even monocationic acridinium derivatives with a phenyl rotor display enhanced FL by fixing on the surface (S-FIE) of saponite clay and the subsequent suppression of molecular movement. 20 Further, another class of more flexible molecules, namely pyridyl-1,3-propandione, has been intercalated between the layered sheets of sumecton to achieve enhanced FL. 21 Inspired by these results, we focus on the conformationally twisted almost nonemissive p-conjugate ATh4PH (Fig.…”