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• New chemo-dosimeter selectively and sensitively senses CN− via dual channel responses and Al(III) via CHEF effect. • Mechanism of CN− sensing involves deprotonation of phenolic -OH group followed by nucleophilic addition at imine C-atom. • 1H & 27Al NMR and mass spectral techniques reveal that Al(III) forms a 1:1 octahedral complex [Al(VDP1)(NO 3) 3 (H 2 O)]. • DFT and TD-DFT calculations confirm that weak fluorescence of the probe is due to CT character of the transition therein non-radiative decay dominates. • MTT assay indicates that the probe is less toxic to HeLa cells and could detect intracellular CN− and Al(III) ions by bioimaging. The selective and sensitive dual channel assay of CN− and fluorescence assay of Al(III) are reported using a simple organic probe (VDP1) in aqueous and non-aqueous media. The binding behaviours of these ionic analytes with VDP1 were studied using UV–Vis, fluorescence, (1H, 13C & 27Al) NMR and mass spectral techniques. VDP1 showed a highly selective change of colour and fluorescence enhancement with CN− ion immediately without interference from other anions. The experimental results revealed that the mechanism of CN− detection involves deprotonation of the phenolic -OH group followed by nucleophilic addition at the imine C-atom. The addition of Al(III) was found to enhance the fluorescence of VDP1 significantly through chelation-enhanced fluorescence effect (CHEF) by forming a 1:1 octahedral complex [Al(VDP1)(NO 3) 3 (H 2 O)]. The Density Functional Theory (DFT) and Time-dependent Density Functional Theory (TD-DFT) based theoretical calculations confirmed that the weak fluorescence of VDP1 is due to the charge transfer (CT) character of the transition in which non-radiative decay dominates. The theoretically computed optical properties matched well with that of experimental observations. The limits of detection (LOD) of these ionic analytes were also calculated and found to be much lower than the corresponding recommended limit set by the World Health Organization (WHO). MTT assay indicated that VDP1 is less toxic to HeLa cells and could detect intracellular CN− and Al(III) ions by bioimaging. [ABSTRACT FROM AUTHOR]

• The ferrocene-based probe colourimetricaly/electrochemicaly sensed HSO 3 − in a 95 % aqueous solution. • Mechanism of sensing was illustrated by 1H & 13C NMR, HR-MS and DFT/TD-DFT analysis. • The plausible mechanism of sensing is via nucleophilic addition of HSO 3 − ion to olefinic C-atom. • The proposed sensing mechanism was well supported by DFT/TD-DFT calculations. • The probe was utilized to estimate the levels of HSO 3 − ions in natural water and red wine samples. A simple ferrocene-based organic probe (AK5) is described for selective and sensitive colourimetric/electrochemical detection of HSO 3 - ions in a 95 % aqueous solution. Upon adding HSO 3 − ions, the colour of the solution changes from brown to colourless instantaneously. The plausible mechanism of detection of HSO 3 − ions by AK5 was illustrated by 1H NMR, 13C NMR, HR-MS and DFT/TD-DFT analysis, which revealed nucleophilic addition of HSO 3 − ion to olefinic C-atom. The limits of detection (LOD) are determined to be 5.58 and 0.12 µM in colourimetric and electrochemical methods, respectively. The probe is successfully applied to estimate the levels of HSO 3 − ions in natural water and red wine samples. [Display omitted] [ABSTRACT FROM AUTHOR]

A new chemo-dosimeter AK4 containing quinoline fluorophore has rationally been designed, synthesised and characterized using 1H and 13C NMR and mass spectral techniques. The probe senses explicitly CN− ion through a dramatic enhancement in fluorescence over other commonly coexistent anions in H2O:DMSO (9:1 v/v) medium over a broad pH range (4–10). 1H NMR titration revealed the deprotonation followed by nucleophilic addition reaction of CN−, which was supported by 13C NMR and mass spectral examinations. The Job’s continuous variation method indicated the formation of a 1:1 adduct between AK4 and CN− with a binding constant of 1.62 × 104 M−1. A limit of detection (LOD) towards CN− of 0.69 µM has been determined, which is much lower than the World Health Organization (WHO) recommended limit of CN− in drinking water (1.9 µM). The changes in the optical properties of AK4 upon reaction with CN− were delineated using Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) calculations. Moreover, fluorescence microscopic studies established that AK4 could be an effective probe for imaging intracellular CN− in HeLa cells. [ABSTRACT FROM AUTHOR]

Different spectroscopic techniques and Density Functional Theory (DFT)/Time-Dependent Density Functional Theory (TDDFT) calculations have been employed to investigate the dual channel CN− detection behaviour of the developed chemo-dosimeter (AK3). The CN− with AK3 reaction triggered a colour change from pale yellow to colourless and enhanced fluorescence. UV–Vis, fluorescence, 1H & 13C NMR and mass techniques coupled with theoretical calculations (Mulliken charges, dihedral angles) revealed that the CN− sensing process mechanism involves deprotonation of the N–H group followed by nucleophilic addition reaction. Detailed TD-DFT calculations showed that the relaxation of excited electrons from LUMO and to two different ground states is responsible for the weak/moderate fluorescence of AK3. Nucleophilic addition of CN− to the C-atom of the CH = CH bridge terminated the π-conjugation between donor and acceptor regions, reduced the coplanarity, decreased the ICT transition and consequently enhanced the fluorescence of the probe. The practical utility of the probe was demonstrated by detecting cyanide in food materials and determining CN− in environmental water samples. [ABSTRACT FROM AUTHOR]