An efficient and ultrasensitive rhodamine B-based reversible colorimetric chemosensor for naked-eye recognition of molybdenum and citrate ions in aqueous solution: Sensing behavior and logic operation

• The described rhodamine B (RhB) chemosensor is commercially available.
• It is the first colorimetric chemosensor for Mo6+ and Cit3− in aqueous media.
• The response of the chemosensor toward Mo6+ and citrate is fast.
• An IMPLICATION logic operation can be achieved using Mo6+ and Cit3− as the inputs.
• Rhodamine B (RhB) chemosensor is a promising candidate for further applications in molecular logic devices.

In this paper we manifest a novel rhodamine B (RhB) based colorimetric chemosensor for molybdenum and citrate ions (Cit3−) in an absolutely aqueous media. It has been identified as highly sensitive probe for Mo6+ which responds at 4.0 nmol L−1 concentration levels. RhB while combined with Mo6+ in aqueous solution displays a color changing from pink to purple which could be quickly dissociated by the addition of citrate in this system so that reversible color changes from purple to pink can be achieved. The comparison of this method with some other methods for citrate indicates that this is the only method which can detect citrate in aqueous solution by color changes. This chemosensor can be applied for quantification of citrate with a linear range covering from 1.67 × 10−7 to 1.22 × 10−5 M and a detection limit of 2.0 × 10−8 M. Moreover, the response of the chemosensor toward Mo6+ and citrate is fast. In addition, based on above sensing mechanism, an IMPLICATION logic operation can be achieved using Mo6+ ion and Cit3− as the inputs, making RhB a promising candidate for further applications in molecular logic devices and also indicates that RhB is suitable for the detection of Mo6+ and Cit3− ions in real samples.

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