A highly selective and sensitive turn-on fluorescence chemosensor based on a rhodamine-adenine conjugate for Al3+ in aqueous medium: Bioimaging and DFT studies

Recently, extraordinary progress has been made for the specific detection of environmentally and biologically relevant metal ions in aqueous solution and living cells. A new dye L where rhodamine B is covalently attached to adenine has been synthesized in good yields. This dye is found to be highly specific in detecting of Al3+ ion in presence of excess of biologically relevant metal ions in DMSO/H2O [1:4 (v/v), HEPES buffer, pH=7.1] medium. Upon complexation with Al3+ the dye exhibits a substantially enhanced absorbance intensity at 566 nm and fluorescence intensity at 590 nm. Besides showing high selectivity, the sensor gives a sensitivity of 0.19 µM for Al3+ in both absorbance and fluorescence studies over a wide pH range. The sensitivity is much higher compared to the value mentioned in the guidelines of WHO (7.41 µM). Moreover, the dye shows moderately cytotoxicity and can be employed for the detection of intracellular concentration of Al3+ ions in living cells.