Significant improved selectivity of a fluorescent sensor for Al3+ made from a fluorinated rhodamine B Schiff base

Synthesis and Applications of Selected Fluorine-Containing Fluorophores

“…Dye 37 is designed by Wan et al to be utilized as a Schiff base chemosensor for aluminum (III) ions [ 43 ]. As seen in Equation (3), compound 36 reacts with 4-fluorobenzaldehyde in methanol at high temperature to synthesize product 37 in a good yield of 85%.…”

“…Table 2 highlights the bathochromic shifts presented by the different fluorinated rhodamine dyes. Some of the most popular modifications made to the rhodamine structure are the addition of alkyl groups to the nitrogen of rhodamine, most commonly adding an azetidine ring or fluorine-containing alkyl groups as seen in compounds 38 – 40 [ 42 , 43 , 46 ]. Fluorine atoms are also typically incorporated into the rhodamine structure on the carbon adjacent to the amino group like in compound 29 , or on the phenyl ring added by the phthalic anhydride precursor as shown in compound 48 or 50 .…”

“…With new classes of rhodamine dyes emerging and new ways to shift fluorescence signals to higher wavelengths, it is crucial to recognize what substituents contribute the most innovation to the field. These compounds offer impressive imaging and selectivity for biomolecules to be applied as sensors for biological systems [ 43 , 44 , 49 ]. In Figure 9 , the rhodamine-based targeting probes are synthesized using fluorinated rhodamine and different ligand attachments (Pepstatin A or (4-Carboxybutyl)triphenylphosphonium) to target the respective cellular organelles [ 44 ].…”

“…Although rhodamine dyes are most notably recognized for their imaging capabilities, it is essential to consider other uses for rhodamines. Compound 37 is used as an aluminum ion sensor [ 43 ]. The study focuses on the different effects electron-withdrawing and electron-donating substituents contribute to functionality as a chemosensor.…”

“… Metal sensing rhodamine dye 37 , selectivity for aluminum ions [ 43 ]. Binding mode in the presence of aluminum ion ( left ), and fluorescence emission spectra ( right ) at increasing concentrations of aluminum ion (0–10 equivalents) with 1 × 10 −5 M of compound 37 in ethanol solution.…”