Coumarin based azo dyes as anion sensors: A spectrophotometric study

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Electronic Supplementary Data

Coumarin based azo dyes as anion sensors: A spectrophotometric study

Nilanjan Chakraborty^a, Sutanwi Bhuiya^b, Arijit Chakraborty^{a, c,}* & Suman Das^b,*

aDepartment of Chemistry, Maulana Azad College, 8, Rafi Ahmed Kidwai Road, Kolkata 700 013, West Bengal, India

bDepartment of Chemistry, Jadavpur University, Kolkata 700 032, West Bengal, India

Email: sumandas10@yahoo.com

cDepartment of Chemistry, Acharya B N Seal College, Cooch Behar 730 161, West Bengal, India

No. Contents Pg No.

1 Fig. S1 – ¹H-NMR of 1 in DMSO-d₆ 3

2 Fig. S2 – ¹³C-NMR of 1 in DMSO-d₆ 3

3 Fig. S3 – ESI-MS spectra of compound 1 4

4 Fig. S4 – ¹H-NMR spectrum of compound 2 in DMSO-d₆ 4

5 Fig. S5 – ESI-MS spectra of compound 2 5

6 Fig. S6 – ¹H NMR spectral changes of 1 in (a) absence and presence of (b) 0.5 equivalent (c) 0.75 equivalent (d) 1 equivalent of tetrabutyl ammonium fluoride in DMSO-d₆

5 7 Fig. S7 – 1- NMR spectral changes of 2 in (a) absence and presence of (b) 0.5 equivalent

(c) 0.75 equivalent (d) 1 equivalent of tetrabutyl ammonium fluoride in DMSO-d₆

6

8 Fig. S8 – (a) UV-vis titration of 1 (5×10^－⁵ M) in CH3CN (2 mL) (curve 1) with the addition of incremental amount of tetrabutyl ammonium hydroxide up to 250 µM (curve 8).

(b) Spectral titration of 2 (2.5×10^－⁵ M) in CH3CN (2 mL) (curve 1) with the addition of incremental amount of tetrabutyl ammonium hydroxide up to 200 µM (curve 8)

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9 Fig. S9 – The changes in the fluorescence spectra of 1 (2.5×10^－⁵ M) and 2 (2.5×10^－⁵ M) upon addition 4 eq. of anions in CH₃CN

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10 Fig. S10 – (a) Fluorescence titration of 1 (2.5×10^－⁵ M) in CH3CN (2 mL) (curve 1) with the addition of incremental amount of AcO^－ up to 150 µM (curve 7). (b) Spectral titration of 2 (2.5×10^－⁵ M) in CH3CN (2 mL) (curve 1) with the addition of incremental amount of AcO^－ up to 50 µM (curve 9)

7

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11 Fig. S11 – Selectivity of the sensor 1 for the anions in presence of interfering anions.

(a): Fluorescence intensity of sensor 1 (2.5 10^－⁵ M) at 495.5 nm in presence of 4 eq. of anions (blue bar) and intensity after further addition of 4 eq. of F^- ions (pink bar).

(b): Fluorescence intensity of sensor 1 (2.5×10^－⁵ M) at 495.5 nm in presence of 4 eq. of F^- ions (blue bar) and intensity after further addition of 4 eq. of anions (pink bar).

(c): Fluorescence intensity of sensor 1 (2.5×10^－⁵ M) at 495.5 nm in presence of 4 eq. of anions (blue bar) and intensity after further addition of 4 eq. of AcO^- ions (pink bar).

(d): Fluorescence intensity of sensor 1 (2.5×10^－⁵ M) at 495.5 nm in presence of 4 eq. of AcO^- ions (blue bar) and intensity after further addition of 4 eq. of anions (pink bar)

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12 Fig. S12 – Selectivity of the sensor 2 for the anions in presence of interfering anions.

(a): Fluorescence intensity of sensor 2 (2.5×10^－⁵ M) at 495.5 nm in presence of 2 eq. of anions (blue bar) and intensity after further addition of 2 eq. of F^- ions (pink bar).

(b): Fluorescence intensity of sensor 2 (2.5 × 10^－⁵ M) at 495.5 nm in presence of 4 eq. of F^- ions (blue bar) and intensity after further addition of 2 eq. of anions (pink bar).

(c): Fluorescence intensity of sensor 2 (2.5 × 10^－⁵ M) at 495.5 nm in presence of 2 eq. of anions (blue bar) and intensity after further addition of 2 eq. of AcO^- ions (pink bar).

(d): Fluorescence intensity of sensor 2 (2.5 × 10^－⁵ M) at 495.5 nm in presence of 2 eq. of AcO^- ions (blue bar) and intensity after further addition of 2 eq. of anions (pink bar)

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13 Fig. S13 – Job’s plot: (a) Binding of F^－ ion with 1 at λ = 422 nm and (b) binding of AcO^－ion with 1 at λ = 422 nm

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14 Fig. S14 – Job’s plot: (a) Binding of F^－ ion with 2 at λ = 416 nm and (b) binding of AcO^－ion with 2 at λ = 416 nm

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15 Fig. S15 – (a) Spectral titration of a mixture 1 (4.0×10^－⁴ M) and F^－ (5.0×10^－⁴M) (curve 1) in CH3CN (2 mL) with the addition of incremental amount of water up to 65 µL (curve 13).

(b) Spectral titration of a mixture 2 (5.0×10^-4 M) and F^－ (5.0×10^-4M) in CH₃CN (2 mL) (curve 1) with the addition of incremental amount of water up to 65 µL (curve 6)

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16 Fig. S16 – (a) Electronic spectra of 1 in various solvents with different polaritiesand (b) Electronic spectra of 2 in various solvents with different polarities

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17 Fig. S17 – B3LYP/6-31G computed structure: (a) 1 and (b) 2 11

18 Fig. S18 – (a) Photograph of the test paper strips with sensor 1 for detecting anions in neutral aqueous solution. (b) Strip in present of 1mg/mL of F^－(left) and 3.5 mg/mL of F^－ (right).

(c) Strip in present of 1mg/mL of OAc^－(left) and 3.5 mg/mL of OAc^－(right)

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19 Scheme S1 – Synthesis of azo dyes 12

20 Scheme S2 – Probable interaction pattern of azo dyes with anions 13

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Fig. S1 – ¹H-NMR of 1 in DMSO-d₆

Fig. S2 – ¹³C -NMR of 1 in DMSO-d₆

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Fig. S3 – ESI-MS spectra of compound 1

Fig. S4 – ¹H-NMR spectrum of compound 2 in DMSO-d₆

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Fig. S5 – ESI-MS spectra of compound 2

Fig. S6 – ¹H NMR spectral changes of 1 in (a) absence and presence of (b) 0.5 equivalent (c) 0.75 equivalent (d) 1 equivalent of tetrabutyl ammonium fluoride in DMSO-d₆

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Fig. S7 – 1- NMR spectral changes of 2 in (a) absence and presence of (b) 0.5 equivalent (c) 0.75 equivalent (d) 1 equivalent of tetrabutyl ammonium fluoride in DMSO-d₆

Fig. S8 – (a) UV-vis titration of 1 (5×10^－⁵ M) in CH₃CN (2 mL) (curve 1) with the addition of incremental amount of tetrabutyl ammonium hydroxide up to 250 µM (curve 8). (b) Spectral titration of 2 (2.5×10^－⁵ M) in CH3CN (2 mL) (curve 1) with the addition of incremental amount of tetrabutyl ammonium hydroxide up to 200 µM (curve 8)

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Fig. S9 – The changes in the fluorescence spectra of

Fig. S10 – (a) Fluorescence titration of 1

of AcO^－ up to 150 µM (curve 7). (b) Spectral titration of of incremental amount of AcO^－ up to 50 µM (curve 9)

The changes in the fluorescence spectra of 1 (2.5×10^－⁵ M) and 2 (2.5×10^－⁵ M) upon addition 4 eq.

(2.5×10^－⁵ M) in CH₃CN (2 mL) (curve 1) with the addition of incremental amount M (curve 7). (b) Spectral titration of 2 (2.5×10^－⁵ M) in CH3CN (2 mL) (curve 1) with the addition

µM (curve 9)

M) upon addition 4 eq. of anions in CH3CN

CN (2 mL) (curve 1) with the addition of incremental amount mL) (curve 1) with the addition

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Fig. S11 – Selectivity of the sensor 1 for the anions in presence of interfering anions. (a): Fluorescence intensity of sensor 1 (2.5×10^－⁵ M) at 495.5 nm in presence of 4 eq. of anions (blue bar) and intensity after further addition of 4 eq. of F^- ions (pink bar).

(b): Fluorescence intensity of sensor 1 (2.5×10^－⁵ M) at 495.5 nm in presence of 4 eq. of F^- ions (blue bar) and intensity after further addition of 4 eq. of anions (pink bar). (c): Fluorescence intensity of sensor 1 (2.5×10^－⁵ M) at 495.5 nm in presence of 4 eq. of anions (blue bar) and intensity after further addition of 4 eq. of AcO^- ions (pink bar). (d): Fluorescence intensity of sensor 1 (2.5×10^－⁵ M) at 495.5 nm in presence of 4 eq. of AcO^- ions (blue bar) and intensity after further addition of 4 eq. of anions (pink bar)

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Fig. S12 – Selectivity of the sensor 2 for the anions in presence of interfering anions. (a): Fluorescence intensity of sensor 2 (2.5×10^－⁵ M) at 495.5 nm in presence of 2 eq. of anions (blue bar) and intensity after further addition of 2 eq. of F^- ions (pink bar).

(b): Fluorescence intensity of sensor 2 (2.5×10^－⁵ M) at 495.5 nm in presence of 4 eq. of F^- ions (blue bar) and intensity after further addition of 2 eq. of anions (pink bar). (c): Fluorescence intensity of sensor 2 (2.5×10^－⁵ M) at 495.5 nm in presence of 2 eq.

of anions (blue bar) and intensity after further addition of 2 eq. of AcO^- ions (pink bar). (d): Fluorescence intensity of sensor 2 (2.5×10^－⁵ M) at 495.5 nm in presence of 2 eq. of AcO^- ions (blue bar) and intensity after further addition of 2 eq.

of anions (pink bar)

Fig. S13 – Job’s plot: (a) Binding of F^－ ion with 1 at λ = 422 nm and (b) binding of AcO^－ion with 1 at λ = 422 nm

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Fig. S14 – Job’s plot: (a) Binding of F^－ ion with 2 at λ = 416 nm and (b) binding of AcO^－ ion with 2 at λ = 416 nm

Fig. S15 – (a) Spectral titration of a mixture 1 (4.0×10^－⁴ M) and F^－ (5.0×10^－⁴M) (curve 1) in CH3CN (2 mL) with the addition of incremental amount of water up to 65 µL (curve 13). (b) Spectral titration of a mixture 2 (5.0×10^-4 M) and F^－ (5.0×10^-4M) in CH₃CN (2 mL) (curve 1) with the addition of incremental amount of water up to 65 µL (curve 6)

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Fig. S16 – (a) Electronic spectra of 1 in various solvents with different polaritiesand (b) Electronic spectra of 2 in various solvents with different polarities

Fig. S17 – B3LYP/6-31G computed structure: (a) 1 and (b) 2

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Fig. S18 – (a) Photograph of the test paper strips with sensor 1 for detecting anions in neutral aqueous solution.

(b) Strip in present of 1mg/mL of F^－(left) and 3.5 mg/mL of F^－ (right). (c) Strip in present of 1mg/mL of OAc^－(left) and 3.5 mg/mL of OAc^－(right)

Scheme S1 – Synthesis of azo dyes

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Scheme S2 – Probable interaction pattern of azo dyes with anions