Journal of Fluorescence
Supplementary Information for
Poly(1-amino-5-chloroanthraquinone): highly selective and ultrasensitive fluorescent chemosensor for ferric ion
Shaojun Huang a,*, Ping Du a, Chungang Min a, Yaozu Liao c, Hui Sun a, Yubo Jiang b
a Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming 650093, China
b Faculty of Science, Kunming University of Science and Technology, Kunming 650093, China
c School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
* Corresponding author. E-mail address:
Electronic Absorption and Fluorescence Measurement
The typical spectrometric and fluorometric measurements were carried out as follows. Polymer–metal complex solutions used for absorption and fluorescence measurements were prepared by mixing a polymer solution (9.0 mL of 6.70 μg/mL) in DMF with 1.0 mL of aqueous metal salt solutions (1.0×10−4 M) (pH 7.0) at room temperature (22 ºC) and then making the solution with a constant volume of 5.0 mL by DMF. The metal ions investigated were Na+, Mg2+, Al3+, K+, Ca2+, Cr3+, Mn2+, Fe3+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Ag+, Cd2+, Ba2+, Ce3+, Hg2+, Pb2+ and Bi3+ as their nitrate salts. Our research showed that no precipitate was observed even though 20% (volume fraction) water was added into the polymer solution in DMF. All of the optical measurements were operated right after the test solutions were prepared and thoroughly mixed. The UV–vis absorption and fluorescence emission spectra were recorded based on these mixed solutions with a constant polymer concentration of 6.03 μg/mL. The slit widths for the excitation and emission were both set at 5.0 nm.
A 1.0×10–3 M Fe(III) standard stock solution was prepared by dissolving Fe(NO3)3·9H2O in 4-(2-hydroxyethyl)-piperazine-1-ethanesulfonic acid (HEPES)–buffered (0.1 M, pH 7.0) solution. Its working solutions were obtained by stepwise dilutions of the stock solutions with HEPES–buffered solution.
Determination of the LOD for detecting Fe3+
Under the same conditions, 5 determinations of the fluorescence emission spectra (λexc=334 nm) of a blank solvent DMF/H2O (9:1, v/v) were carried out to obtain the baseline noise. The average of the baseline noise (N) was found to be 3.9282. Assuming that the relative intensity of signal (S), i.e. ΔF (ΔF=F0−F), is 3 times that of N, together with the known F0 value of 259.65, the calculated values of ΔF and F are 11.7846 and 247.87, respectively. Then substituting these values into the following equation can get the value of the LOD, which was calculated to be 2.0×10–11 M.
Where F0 and F are the fluorescence intensities of the PACA solution in absence and presence of metal ion, respectively.
The fluorescence titration experiment was also conducted so as to find out the LOD for detecting Fe3+. As can be seen from Fig. S1, in comparison with the F0, the fluorescence intensity (F) at 417 nm underwent only a very slight decrease even within the permissible error range at the Fe3+ concentration below 2.0×10–11 M. By contrast, the F at 417 nm underwent a relatively large decrease at the Fe3+ concentration equal to or above 2.0×10–11 M. So we believe that the LOD for detecting Fe3+ is exactly 2.0×10–11 M based on the fluorescence titration, which is the same to that obtained by theoretical calculation mentioned above.
Fig. S1 Fluorescence spectral changes of PACA (6.03 μg/mL) with different concentrations of Fe3+ ion (6.0×10−12 ~ 9.0×10−11 M) in DMF/H2O (9:1, v/v) (λexc=334 nm); inset shows regional magnified fluorescence spectra.
Table S1 Comparison of Synthesis Complexity, Linear Range and Detection Limit in Fe3+ Analysis
Methods / Fe3+ receptor structure / One–potsynthesis / Linear range (M) / Detection
limit (M)
CP600 (3´10–6 M) in aqueous solution at pH 7.0 [1] / / no / 0–1.0´10–6 / not given
N,N-diethylsulfonate-1- aminomethylnaphthalene (2´10–5 M) in aqueous solution at pH 7.0 [2] / / yes / 1.6´10–5–
6.3´10–5 / 2´10–6
1-Naphthalene methyliminodiacetohydroxamic acid (1´10–5 M) in MeOH/H2O (1:1) at pH 3 [3] / / no / 10–5–10–4 / 5´10–6
NT (1.0´10–5 M) in a THF/H2O (9:1) solvent system buffered at pH 7.4 [4] / / yes / 1.7´10–5–
3.7 ´10–5 / not given
Condensation product of 2-hydroxy-1-naphthaldehyde and 2,6-diaminopyridine (1.0´10–5 M) in THF/H2O (9:1) HEPES buffer solution at pH 7.0 [5] / / yes / 5.0´10–5–
1.2 ´10–4 / not given
Rhodamine-based fluorescence sensor (RC) (1.0´10–4 M) in HEPES buffer solution at pH 7.2 [6] / / yes / 6.0´10–8–
7.2´10–6 / 1.4´10–8
Rhodamine 6G Schiff base FS1 (1.0 mM) in H2O/CH3CN(95:5) [7] / / yes / not given / 1.0´10–7
AD-SRhB/β-CD-DNS (1´10–4 M) in HEPES buffer at pH 7.2 [8] / / no / 1.0´10–6–
5´10–5 / 1.0´10–6
BDP derivative (1´10–6 M) in MeCN or MeOH [9] / / no / 10–7–10–4 / not given
BOD-NHOH (1.0´10–6 M) in 40 mM, pH 7.0 HEPES aqueous buffer [10] / / no / 0–5.0´10–5 / not given
Dipodal Schiff base sensor (2.5´10–5 M) in THF/H2O (9:1) HEPES buffer solution at pH 7.0 [11] / / no / 5.0´10–6–
8.0´10–5 / not given
Azotobactin δ (2´10–6 M) in MeOH-H2O( 8:2) acetate buffer at pH 4.4 [12] / / no / 0–1.7´10–6 / 8.95´10–9
1-Naphthylamine-tethered epoxy-based polymer (1.49´10–4 M) in THF/H2O (8:2) solution [13] / / yes / 1.0´10–4–
3.7´10–4 / not given
Ploypyrene (2.25´10–5 M) a in NMP/H2O (9:1) [14] / / yes / 1.0´10–5–
1.0´10–3 / not given
PACA (2.36×10–5 M) a in DMF/H2O (9:1) at pH 7.0 [this work] / / yes / 1.0×10–10–
1.0×10–4 / 2.0×10–11
a relative to repeat unit on polymer chain
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