Highly sensitive detection of cobalt through fluorescence changes in β-cyclodextrin-bimane complexes

Abstract

A supramolecular complex of syn-(methyl,methyl)bimane (1) and β-cyclodextrin demonstrates a sensitive (limit of detection = 0.60 nM) and selective fluorescence turn-off response in the presence of cobalt in aqueous media,...

Facile Iodine Detection via Fluorescence Quenching of β‐Cyclodextrin:Bimane‐Ditriazole Inclusion Complexes

“…Interestingly, introducing the iodine analyte to a solution of compound 1 complexed with β‐cyclodextrin (1 : 1 water: acetonitrile) led to highly similar photophysical responses (see ESI for more details), with iodine‐induced decreases in the fluorescence emission spectrum and increases in the UV‐visible absorption spectrum. This result is in contrast to what we observed for the detection of cobalt using a complex formed between bimane 2 and β‐cyclodextrin, where complexation caused a marked improvement in solution‐state fluorescence detection [17] . We speculate that this differential behavior of the cyclodextrin‐bimane complexes for the different bimane fluorophores is likely due to the fact that bimane 1 binds β‐cyclodextrin predominantly around the triazole termini ( vide infra for 1 H NMR confirmation), and that the bimane core which is responsible for the analyte‐induced fluorescence changes is largely unaffected.…”

“…Bimane as a fluorescent scaffold has a number of advantages, including its small size and high quantum yield, that make it particularly attractive for detection applications [15] . Recent joint work by our research groups has exploited the high affinity binding of bimane in β‐cyclodextrin, reported initially by Politzer and co‐workers, [16] to develop highly sensitive and selective fluorescence‐based cobalt sensors [17] …”

“…The detection of iodine using supramolecular bimane‐cyclodextrin complexes has not been reported to date, despite the fact that iodine has been shown to interact with organic molecules in general, including both organic fluorophores [18] and cyclodextrin derivatives, [19] and despite the fact that the complex formed between bimane and β‐cyclodextrin has been previously shown to facilitate high performance sensing applications [17] . Reported herein are the results of our successful efforts to realize precisely this objective: the use of a fluorescent complex formed from the novel bimane ditriazole 1 (Figure 1) and β‐cyclodextrin to facilitate the sub‐nanomolar detection of iodine, using both solution‐state supramolecular sensors and paper supports on which the supramolecular sensor has been adsorbed.…”

Highly Sensitive Water Detection Through Reversible Fluorescence Changes in a syn-Bimane Based Boronic Acid Derivative

“…Of note, all aqueous studies were conducted in double deionized water, so that no interference and/or fluorescence quenching occurred due to residual metal ions. Such ions, in particular palladium ( Das et al, 2016 ), sodium ( Roy et al, 2018 ), and cobalt ( Pramanik et al, 2020 ), have been shown to complex effectively to the bimane core, leading to marked changes in the bimane’s photophysical properties. Also of note, the existence of trace amounts of water even in the “0%” water is likely, based on literature precedent ( Son et al, 2001 ), but this trace amount of water is accounted for as part of the baseline for our fluorescence quenching experiments, in accordance with literature precedent ( Porter and Markham 1970 ).…”

“…Recent reports from one of our research groups have demonstrated the development of high-performance fluorometric ( Haynes and Levine 2020 ) and colorimetric ( Haynes et al, 2019 ) sensors for a variety of organic and inorganic analytes. Moreover, recent successes in novel sensor development have been reported in joint publications from our research groups, and demonstrate that bimane-based supramolecular constructs act as highly effective sensors for cobalt (II) ions ( Pramanik et al, 2020 ) and for molecular iodine ( Pramanik et al, 2021 ). These sensors, which operate in both solution-state and on filter papers to provide fluorometric and colorimetric analyte detection, have notable practical advantages, including their high sensitivity, ease of access, and non-toxicity of both the bimane transducing element and supramolecular cyclodextrin scaffold.…”