Limits...
Colorimetric Cyanide Chemosensor Based on 1',3,3',4-Tetrahydrospiro[chromene-2,2'-indole].

Dagilienė M, Martynaitis V, Kriščiūnienė V, Krikštolaitytė S, Šačkus A - ChemistryOpen (2015)

Bottom Line: These chemosensors show a distinct color change when treated with cyanide in acetonitrile solution buffered with sodium phosphate, and this procedure is not affected by the presence of other common anions.The mechanism for detection is rationalized by the nucleophilic substitution of the phenolic oxygen atom at the indoline C-2 atom by the cyanide anion to form a stable indolylnitrile adduct and to generate the colored 4-nitrophenolate chromophore.These chemosensors can be synthesized by a simple procedure from commercially available starting materials.

View Article: PubMed Central - PubMed

Affiliation: Institute of Synthetic Chemistry, Kaunas University of Technology Radvilėnų pl. 19, 50254, Kaunas, Lithuania ; Department of Organic Chemistry, Kaunas University of Technology Radvilėnų pl. 19, 50254, Kaunas, Lithuania.

ABSTRACT
A new class of chemosensors based on the 1',3,3',4-tetrahydrospiro[chromene-2,2'-indole] ring system, which detects cyanide with high specificity, is described. These chemosensors show a distinct color change when treated with cyanide in acetonitrile solution buffered with sodium phosphate, and this procedure is not affected by the presence of other common anions. The chemisensors exhibit high sensitivity to low concentrations of cyanide, meeting the European Union water quality control criterion of sensitivity below 0.05 mg L(-1), and show a very fast response within tens of seconds. The mechanism for detection is rationalized by the nucleophilic substitution of the phenolic oxygen atom at the indoline C-2 atom by the cyanide anion to form a stable indolylnitrile adduct and to generate the colored 4-nitrophenolate chromophore. These chemosensors can be synthesized by a simple procedure from commercially available starting materials.

No MeSH data available.


Related in: MedlinePlus

Absorbance changes at 422 nm for 8 e–h and at 411 nm for 1 (0.1 mm, 298 K) in a mixture of CH3CN/phosphate buffer (Na2HPO4/NaH2PO4, 7.5 mm, pH 7.6) (19:1 v/v) after addition of NaCN (10 equiv).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4522186&req=5

fig05: Absorbance changes at 422 nm for 8 e–h and at 411 nm for 1 (0.1 mm, 298 K) in a mixture of CH3CN/phosphate buffer (Na2HPO4/NaH2PO4, 7.5 mm, pH 7.6) (19:1 v/v) after addition of NaCN (10 equiv).

Mentions: For various types of chemosensors, the response time is very important for the practical detection of analytes. In our case, we observed that the response time depends on the structure of the compound. After the addition of sodium cyanide to the solutions of compounds 8 a–d, a strong new absorption band at 422 nm appeared within 1–3 min (Figure 4), while for compounds 8 e,f, this process took up to 1.5 h (Figure 5). We concluded that the presence of a nitro group at C-5 of the indole nucleus stabilizes the closed form of the molecule and slows down the formation of the final adduct 9 e,f. Both electronic and steric effects can be considered for explaining the influence of the allyl and benzyl groups at the indole nitrogen atom on the formation of adducts 9 g,h after the addition of sodium cyanide to a solution of compounds 8 g,h, respectively. The response time of the reference compound, 2,8-dinitroindolo[2,1-b][1,3]benzoxazine 1, was evaluated in analogous conditions, and the formation of colored adduct 2 proceeds more slowly in comparison with compounds 8 a–d. The full process takes approximately 20 min (Figure 5), similar to that of compounds 8 g,h.


Colorimetric Cyanide Chemosensor Based on 1',3,3',4-Tetrahydrospiro[chromene-2,2'-indole].

Dagilienė M, Martynaitis V, Kriščiūnienė V, Krikštolaitytė S, Šačkus A - ChemistryOpen (2015)

Absorbance changes at 422 nm for 8 e–h and at 411 nm for 1 (0.1 mm, 298 K) in a mixture of CH3CN/phosphate buffer (Na2HPO4/NaH2PO4, 7.5 mm, pH 7.6) (19:1 v/v) after addition of NaCN (10 equiv).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4522186&req=5

fig05: Absorbance changes at 422 nm for 8 e–h and at 411 nm for 1 (0.1 mm, 298 K) in a mixture of CH3CN/phosphate buffer (Na2HPO4/NaH2PO4, 7.5 mm, pH 7.6) (19:1 v/v) after addition of NaCN (10 equiv).
Mentions: For various types of chemosensors, the response time is very important for the practical detection of analytes. In our case, we observed that the response time depends on the structure of the compound. After the addition of sodium cyanide to the solutions of compounds 8 a–d, a strong new absorption band at 422 nm appeared within 1–3 min (Figure 4), while for compounds 8 e,f, this process took up to 1.5 h (Figure 5). We concluded that the presence of a nitro group at C-5 of the indole nucleus stabilizes the closed form of the molecule and slows down the formation of the final adduct 9 e,f. Both electronic and steric effects can be considered for explaining the influence of the allyl and benzyl groups at the indole nitrogen atom on the formation of adducts 9 g,h after the addition of sodium cyanide to a solution of compounds 8 g,h, respectively. The response time of the reference compound, 2,8-dinitroindolo[2,1-b][1,3]benzoxazine 1, was evaluated in analogous conditions, and the formation of colored adduct 2 proceeds more slowly in comparison with compounds 8 a–d. The full process takes approximately 20 min (Figure 5), similar to that of compounds 8 g,h.

Bottom Line: These chemosensors show a distinct color change when treated with cyanide in acetonitrile solution buffered with sodium phosphate, and this procedure is not affected by the presence of other common anions.The mechanism for detection is rationalized by the nucleophilic substitution of the phenolic oxygen atom at the indoline C-2 atom by the cyanide anion to form a stable indolylnitrile adduct and to generate the colored 4-nitrophenolate chromophore.These chemosensors can be synthesized by a simple procedure from commercially available starting materials.

View Article: PubMed Central - PubMed

Affiliation: Institute of Synthetic Chemistry, Kaunas University of Technology Radvilėnų pl. 19, 50254, Kaunas, Lithuania ; Department of Organic Chemistry, Kaunas University of Technology Radvilėnų pl. 19, 50254, Kaunas, Lithuania.

ABSTRACT
A new class of chemosensors based on the 1',3,3',4-tetrahydrospiro[chromene-2,2'-indole] ring system, which detects cyanide with high specificity, is described. These chemosensors show a distinct color change when treated with cyanide in acetonitrile solution buffered with sodium phosphate, and this procedure is not affected by the presence of other common anions. The chemisensors exhibit high sensitivity to low concentrations of cyanide, meeting the European Union water quality control criterion of sensitivity below 0.05 mg L(-1), and show a very fast response within tens of seconds. The mechanism for detection is rationalized by the nucleophilic substitution of the phenolic oxygen atom at the indoline C-2 atom by the cyanide anion to form a stable indolylnitrile adduct and to generate the colored 4-nitrophenolate chromophore. These chemosensors can be synthesized by a simple procedure from commercially available starting materials.

No MeSH data available.


Related in: MedlinePlus