Supplementary Information
2,6-Bis(2-benzimidazolyl)pyridine fluorescent red-shifted sensor for recognition of zinc(II) and a calorimetric sensor for iron ions
Bita Vosough Razavia, Alireza Badieia,b,*, Negar Lashgaria, Ghodsi Mohammadi Ziaranic,d
a School of Chemistry, College of Science, University of Tehran, Tehran, Iran
b Nanobiomedicine Center of Excellence, Nanoscience and Nanotechnology Research Center, University of Tehran, Tehran, Iran
c Department of Chemistry, Alzahra University, Tehran, Iran
d National laboratory of pharmaceutical research, Alzahra University, Tehran, Iran
*Corresponding author, E-mail address: , Tel.: +98 2161112614.
Fax: +98 2161112614.
1. Fluorescence studies------2
1.1. Fluorescence cation test------2
1.2. Job’s plot for Zn2+------2
1.3. Competition with other metal ions------2
1.4. Fluorescence titration------3
1.5. pH test------3
2. Optical changes------3
3. UV-vis studies------3
3.1. UV-vis cation test------3
3.2. UV-vis titration------3
3.3 Job’s plot for Fe2+ and Fe3+------4
3.4. Competition with other metal ions------4
4. Supplementary figures------4
4.1. Fig. S1. IR spectrum of 2,6-bis(2-benzimidazolyl)pyridine ------4
4.2. Fig. S2. Job’s plot for Zn2+------4
4.3. Fig. S3. Competition of Zn2+ with other metal ions------5
4.4. Fig. S4. Job’s plots for Fe2+ and Fe3+------6
1. Fluorescence studies
1.1. Fluorescence cation test
3 mL of the 10-5 M solution of bbp in CH3CN/H2O (9:1, v/v) was taken, 100 μL of each metal ions, 1 × 10-2 M, was added to it, to give 33 equivalent of cations. The fluorescence spectra were recorded after each addition of different metal ions. (Fig. 1).
1.2. Job’s plot for Zn2+
The fluorescent job’s plot was recorded by measuring the intensity of different mixing 1×10-2 M solutions of ligand and Zn2+ in CH3CN/H2O (9:1, v/v) with the total volume of 10 mL. (Fig. S2).
1.3. Competition with other metal ions
100 μL of Zn2+ (1 × 10-2 M) and 100 μL of each metal ion (1 × 10-2 M), as interfering agents, were taken and added to 3mL of the 10-5 M solution of receptor bbp in CH3CN/H2O (9:1, v/v). After mixing for a few seconds, the fluorescence spectra were recorded. (Fig. 2) and (Fig. S3).
1.4. Fluorescence titration
3 mL of the 10-5 M solution of bbp in CH3CN/H2O (9:1, v/v) was taken, after each addition of increased concentrations of Zn2+ (1 × 10-2 M) the fluorescence spectrum was recorded. (Fig. 3).
1.5. pH test
3 mL of the 10-5 M solution of bbp in CH3CN/H2O (9:1, v/v) was taken, 100 μL of Zn2+ (1 × 10-2 M) was added to it. The fluorescence spectra were recorded after each adjustment of pH. (Fig. 4).
2. Optical changes
33 equivalent of each metal ion was added to the ligand’s solution in CH3CN/H2O (9:1, v/v) at room temperature. The final color changes were observed. (Fig. 5).
3. UV-vis studies
3.1. UV-vis cation test
3 mL of the 10-4 M solution of bbp in CH3CN/H2O (9:1, v/v) was taken, 60 μL of each metal ions, 1 × 10-2 M, was added to it, to give 2 equivalent of cations. The UV-visible spectra were recorded after each addition of different metal ions. (Fig. 6).
3.2. UV-vis titration
3 ml of 10-4 solution of bbp in CH3CN/H2O (9:1, v/v) was taken, after each addition of increased concentrations of Fe2+ or Fe3+, 1 × 10-2 M, the UV-vis spectra were recorded. (Fig. 7).
3.3. Job’s plot for Fe2+ and Fe3+
The fluorescent job’s plot was recorded by measuring the intensity of different mixing 1×10-2 M solutions of ligand and Fe2+ and Fe3+ in CH3CN/H2O (9:1, v/v) with the total volume of 10 mL. (Fig. S4)
3.4. Competition with other metal ions
60 μL of Fe2+ or Fe3+ (1 × 10-2 M) and 60 μL of each metal ion (1 × 10-2 M), as interfering agents, was taken and added to 3mL of the 10-4 M solution of receptor bbp in CH3CN/H2O (9:1, v/v). After mixing for a few seconds, the fluorescence spectra were recorded. (Fig. 8).
4. Supplementary figures
4.1. Fig. S1. IR spectrum of 2,6-bis(2-benzimidazolyl)pyridine
Fig. S1. IR spectra of 2,6-bis(2-benzimidazolyl)pyridine; FT-IR (cm-1): 3143, 1608, 1576, 1468, 1442, 13159, 1283, 1238, 848, 731
4.2. Fig. S2. Job’s plot for Zn2+
Fig. S2. Job’s plot of bbp and Zn2+ in CH3CN/H2O (9:1, v/v) at 438 nm absorbance wavelength.
4.3. Fig. S3. Competition of Zn2+with other metal ions
Fig. S3. Fluorescence spectra of bbp (1×10-5 M) before and after addition of 33 equiv of Zn2+ and 33 equiv of other metal ions including k+, Na+,Co2+, Ni2+ ,Ca2+, Mn2+, Hg2+, Pb2+, Fe3+, Fe2+, Mg2+, Al3+, Cr3+ and Cu2+ in CH3CN/H2O (9:1, v/v).
4.4. Fig. S4. Job’s plots for Fe2+ and Fe3+
Fig. S4. Job’s plots for 1:2 stoichiometric ratio of Fe2+ to [Fe2+-bbp] at 566 nm absorbance wavelength (a), and 2:1 of Fe3+ to [Fe3+-bbp] at 400 nm absorbance wavelength (b)
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