Restriction‐Induced Luminescence Enhancement in 2D Interlayer Supramolecular Infinite Solid Solution for Cell Imaging

Abstract Considering the anionic intercalation capacities of layered double hydroxides (LDH), 2‐hydroxy‐4‐methoxybenzophenone‐5‐sulfonate (BP4) and decanesulfonate (DES) anions are cointercalated into the interlayers of Mg₂Al‐LDH to form DES–BP4 (x%)/LDH composites, which can be regarded as 2D interlayer supramolecular infinite solid solutions (2D ISISSs), according to a structural analysis. Compared to those of pristine BP4, the fluorescence properties of DES–BP4 (x%)/LDH 2D ISISSs are significantly improved and their emission peak wavelengths are adjustable in the range of 491–510 nm by varying x. DES–BP4 (8%)/LDH exhibits the optimal fluorescence properties. Its quantum yield, lifetime, and fluorescence intensity are increased ≈14, 4, and 45 times, respectively. Moreover, its nonradiative relaxation rate constant is decreased five times, while its radiative relaxation rate constant is increased three times. The luminescence enhancement can be attributed to the formation of the 2D ISISSs system, which effectively restricted the intramolecular movements of BP4 anions. Owing to its enhanced fluorescence properties, DES–BP4 (8%)/LDH exhibits outstanding performances for cell penetration and confocal fluorescence imaging and lifetime imaging of lysosome in HeLa cells. Therefore, the 2D ISISSs based on the LDH matrix provide a novel route to optimize the performances of functional molecules and expand their applications.