Abstract
Aims and objective: 2-Thienylbenzimidazole (TBI)/cucurbit[7]uril (CB7) host/guest complex was used to significantly improve the detection of Hg2+ in water samples.
Methods: The unique mechanism of the sensing process is based on the binding of CB7 host to TBI guest. The host-guest complexation was confirmed by UV-visible absorption, time-resolved fluorescence, and proton NMR spectroscopy. The complexations of TBI and TBI/CB7 with Hg2+ ions in solid-state were confirmed by FTIR, mass, and TGA. The most stable structures were unfolded by DFT calculations.
Results: In an aqueous solution, a five-fold higher stability constant of the protonated TBIH+/CB7 complex was observed when compared to the neutral TBI/CB7 complex as manifested in an increase in pKa values by ~ 0.5 unit in an excited state. The static fluorescence quenching of TBI on binding to Hg2+ ions was significantly enhanced in the presence of CB7.
Conclusion: Macrocycles are useful additives for the highly sensitive recovery of mercury ions in water samples.
Keywords: Mercuric ions recovery, host-guest chemistry, fluorescence, static quenching, DFT calculations, host-induced pKa shifts.
Graphical Abstract
[http://dx.doi.org/10.1002/9781119113874.ch13]
[http://dx.doi.org/10.1039/c3nr00580a] [PMID: 23632769]
[http://dx.doi.org/10.1039/c002219p] [PMID: 20407667]
[http://dx.doi.org/10.1139/V10-079]
[http://dx.doi.org/10.1021/jp405553g] [PMID: 24090492]
[http://dx.doi.org/10.1016/j.saa.2021.119656] [PMID: 33744695]
[http://dx.doi.org/10.1039/c3tb20852d] [PMID: 32261098]
[http://dx.doi.org/10.1021/cm503304p] [PMID: 25620848]
[http://dx.doi.org/10.1002/anie.200902596] [PMID: 19725085]
[http://dx.doi.org/10.1021/ac400919j] [PMID: 23919280]
[http://dx.doi.org/10.1080/10610278.2020.1856845]
[http://dx.doi.org/10.1039/b922778d] [PMID: 20473436]
[http://dx.doi.org/10.1016/j.rinp.2020.103168]
[http://dx.doi.org/10.1088/2040-8978/14/11/114010]
[http://dx.doi.org/10.1002/jcc.1056]
[http://dx.doi.org/10.1002/jcc.10255] [PMID: 12759913]
[http://dx.doi.org/10.1103/PhysRevLett.77.3865] [PMID: 10062328]
[http://dx.doi.org/10.1063/1.478813]
[http://dx.doi.org/10.1002/jcc.20495] [PMID: 16955487]