Chromogenic anionic chemosensors based on protonated merocyanine solvatochromic dyes: Influence of the medium on the quantitative and naked-eye selective detection of anionic species

Anionic chromogenic chemosensors highly selective for fluoride or cyanide based on 4-(4-Nitrobenzylideneamine)phenol

“…In the presence of an excess of the anion, the compound is deprotonated with the formation of a [HA 2 ] -complex. 12,13 This is corroborated by the fact that the experimental data used to obtain the titration curve could not be fitted using equation 1, but only with equation 2, which considers both 1:1 and 1:2 2a:anion stoichiometries.…”

“…A plot of the absorbance values at 547.0 nm as a function of c(CN -) (Figure 3b) shows a behavior typical of a 1:1 2a:CN -stoichiometry. The experimental data were fitted with the use of equation 1,[12][13][14]40,41 where Abs is the absorbance value after each addition of the anion, Abs 0 is the initial absorbance without anion added, Abs 11 is the maximum absorbance value obtained by addition of the anion considering 1:1 2a:anion stoichiometry, c(A -) is the anion concentration in each addition, and K 11 is the binding constant.…”

“…The acidity of the chemosensor can be improved by combining the effect of the medium polarity with modifications in the molecular structure of the compound. 12,13 A set of protonated dyes with phenol donor groups in their molecular structures has been studied by our group as simple anionic chromogenic chemosensors based on acid-base strategy. [11][12][13][14] One of these dyes is 4-(4-nitrobenzylideneamine)-2,6-diphenylphenol, compound 1a, which was recently used to selectively detect CN -in the presence of several anionic species in acetonitrile with very small amounts of water.…”

“…Phenol groups are commonly used in the molecular structure of these types of chemosensors. [10][11][12][13][14] The connection of the phenol donor group to an acceptor group through a conjugated bridge creates an interesting feature since the deprotonation of the compound generates a colored conjugated base. The acidity of the chemosensor can be improved by combining the effect of the medium polarity with modifications in the molecular structure of the compound.…”

A TD‐DFT study on the cyanide‐chemosensing mechanism of 8‐formyl‐7‐hydroxycoumarin

“…15,16,[18][19][20][21][22][23][24] A few chemosensors of them containing XÀ ÀH moieties (where X is an electronegative atom such as N or O) moieties enable selective anion recognition in aqueous solution. 18,19 It is noted that a p-system bearing an XÀ ÀH moiety may be an appropriate candidate for designing chemosensors for anions. Upon adding the anion, the XÀ ÀH bond is weakened by the negative charge (anion or other functional groups), which favors PT in the ground state or ESPT.…”