A highly sensitive fluorescence “turn on” detection of perrhenate Anion, a non-radioactive surrogate of hazardous pertechnetate anion

• Published in: Sensors and actuators. B, Chemical Vol. 323; p. 128675
• Main Authors: Pandey, Shrishti P., Desai, Akshat M., Singh, Prabhat K.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15-11-2020; Elsevier Science Ltd
• Subjects: aggregation; Anions; Aqueous solutions; Charge density; Colorimetry; cyanine dyes; Emission; Fluorescence; fluorescence sensor; Fluorimetry; molecular rotor; Perrhenate sensor; pertechnetate; molecular rotor; Perrhenate sensor; aggregation; cyanine dyes; pertechnetate; fluorescence sensor
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2020.128675

A fluorescence “turn on” detection of Perrhenate anion has been achieved which is based on emissive J-aggregates of a cyanine based molecular rotor.
[Display omitted]
•The sensor produces a fluorescence turn-on response for perrhenate anion.•The sensor records very high fluorescence increase (∼60 fold) for perrhenate anion.•Sensing scheme is based on perrhenate induced J-aggregate formation of probe.•High selectivity for perrhenate among environmentally ubiquitous anionic species.•Emission and excitation wavelength of the probe lies in advantageous red region.
Perrhenate oxoanion is a non-radioactive surrogate of the radioactive and hazardous pertechnetate oxoanion. The efficient sensor systems for perrhenate anion in aqueous medium is barely reported and still remains challenging due to low charge density and large size of the anion. In this regard, we have identified a cyanine based molecular rotor probe, pseudoisocyanine, which produces an appreciably larger emission enhancement of ∼60 fold in response to perrhenate anion, which is highest reported, till date, for any turn-on sensor for perrhenate anion leading to a significant improvement in the detection limit (0.17 μM) over existing sensors for perrhenate. Our sensing scheme operates through the ion pairing interaction between perrhenate and pseudoisocyanine which induces the formation of J-aggregates of pseudoisocyanine that yield dramatic changes in its fluorescence properties. The J-aggregate formation of pseudoisocyanine, in the presence of perrhenate anion, also yields significant changes in the absorption properties providing an opportunity of dual sensing of perrhenate, i.e. via fluorimetry and colorimetry. Apart from being sensitive and selective, our probe molecule exhibits a desirable feature of emission and excitation wavelength lying in the red region of the visible specrum which is advantageous for operation of a probe molecule in complex sensing matrix.