Development of Rhodamine 6G-Based Fluorescent Chemosensors for Al(3+)-Ion Detection: Effect of Ring Strain and Substituent in Enhancing Its Sensing Performance

[Image: see text] Four rhodamine 6G-based chemosensors (H(3)L1–H(3)L4) are designed for selective detection of Al(3+) ion. They are characterized using various spectroscopic techniques and X-ray crystallography. All absorption and emission spectral studies have been performed in 10 mM N-(2-hydroxyethyl)piperazine-N′-ethanesulfonic acid (HEPES) buffer solution at pH 7.4 in H(2)O/MeOH (9:1, v/v) at 25 °C. In absorption spectra, chemosensors exhibit an intense band around 530 nm in the presence of Al(3+) ion. Chemosensors (H(3)L1–H(3)L4) are nonfluorescent when excited around 490 nm. The presence of Al(3+) ion enhances the emission intensity (555 nm) many times. The formation of complexes 1–4 is established with the aid of different spectroscopic techniques. The limit of detection value obtained in the nanomolar range confirms the high sensitivity of the probes toward Al(3+) ion. It has been observed that the presence of aliphatic spacers in the diamine part and different halogen substituents in the salicylaldehyde part strongly influences the selectivity of the chemosensors toward Al(3+) ion. The propensity of the chemosensors to identify intracellular Al(3+) ions in triple-negative human breast cancer cell line MDA-MB-468 by fluorescence imaging is also examined in this study.