Simultaneous Detection and Removal of Metal Ions based on a Chemosensor Composed of aRhodamine Derivative and Cyclodextrin Modified Magnetic Nanoparticles

Dongjian Shiab, Ming Nia, Jinfeng Zenga, Jin Yea, Peihong Nib, Xiaoya Liua and Mingqing Chen*a

aThe Key Laboratory of Food Colloids and Biotechnology Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, P. R. China

bJiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Soochow University, 215123, P. R. China

Corresponding Author

Prof. Mingqing Chen

E-mail:

Contents:

1. Synthesis of AD-MAH-RhB.

2. Mechanism studies

3. Synthesis of CD-functionalized magnetic nanoparticles (CD-MNP)

4. Removal of metal ions

1. Synthesis of AD-MAH-RhB.

The chemsensor was synthesized as following (Scheme S1).Maleic anhydride (1 mmol)，RhB (1 mmol) and 4-dimethylamiopyridine (DMAP, 0.15 mmol) were dissolved in DMSO. Then, 1-ethyl-3-(3-Dimethylaminopropyl) carbodiimide (EDC, 1 mmol), hydroxybenzotriazole (HOBt, 1 mmol) and 1-aminoadamantane (AD-NH2, 1 mmol)were added into the above solution. After predetermined time, solvent was removed under reduced pressure to give an red powder and purified by slilica gel column chromatography in CH2Cl2 to give purified AD-MAH-RhB probe.

Scheme S1. Synthesis of AD-MAH-RhB.

1H NMR (400MHz，CDCl3，σ，ppm, Fig. S1): 7.88-7.85 (m, 1H), 7.45-7.42 (J=3.2, 2H), 7.09-7.07 (m, 1H), 6.44-6.26 (m, 8H), 3.37-3.26 (J=7.2, 12H), 2.11-1.88 (m, 2H), 1.90-1.70 (17H, adamantyl imine), 1.18-1.14 (J=7.2, 12H).

Fig. S1. 1H NMR spectrum of AD-MAH-RhB.

13C NMR (400MHz，CDCl3，σ，ppm, Fig. S2): (a) carbon in benzene, (b) carbon in amide, (c) carbon in unsaturated olefin, (d) carbon in methylene adjacent to nitrogen atoms, (e) carbon in methyl, (f) quaternary carbon atom, and (h) carbon in all methylene.

Fig. S2. 13C NMR spectrum of AD-MAH-RhB

Mass spectrum was shown in Fig. S3. The result showed ESI m/z [M+Na+] of AD-MAH-RhB at 738.5.

Fig. S3. Mass spectrum of AD-MAH-RhB

Element analysis was also performed to analysis the structure. The results of each element were C 70.43%, N 9.26%, and H 7.88%. Specifically, for AD-MAH-RhB probe, the molecular structure is C44N5H53O4, and the theoretic amounts of C, N, and H element were 73.84%, 9.79% and 7.41%, respectively. Thus, the theoretic result is similar to the analytic result.

All these results indicated successful preparation of AD-MAH-RhB probe.

2. Mechanism studies.

The binging position of the complexes were also determined by 1H-NMR spectra (Fig. S4). It could be seen that the chemical shift of the double carbon group om AD-MAH-RhB@Hg2+ (Fig. S4a) had an obviously changed from 6.3 ppm to 6.7 ppm, compared with AD-MAH-RhB (Fig. S4b). This indicated the unsaturated olefin was changed by addition of Hg2+. For AD-MAH-RhB@Fe3+ complex (Fig. S4c), an obviously shift at 2.5 ppm that belongs to the methylene adjacent to nitrogen atoms was observed, suggesting formation the AD-MAH-RhB@Fe3+ complex between nitrogen atoms and Fe3+.

Fig. S4. 1H NMR spectra of AD-MAH-RhB@Hg2+ (a), AD-MAH-RhB (b) and AD-MAH-RhB@Fe3+ (c)

3. Synthesis of CD-functionalized magnetic nanoparticles (CD-MNP)

Fe3O4 nanoparticles were prepared by Fe2+ and Fe3+ in the present of NH3∙H2O, according to the traditional co-precipitation method[29], and then modified by APTES to get amine-functionalized MNP (MNP-NH2). Finally, pre-prepared mono-6-deoxy-6-(p-tolysulfonyl)-β-cyclodextrin (6-Ts-O-β-CD) and MNP-NH2 suspended in dried N-methylpyrrolidone, and the mixture was sonicated for 20 min before adding KI (0.010 g) under nitrogen at 70 oC. The products were obtained by repeating the procedure of magnetic decantation for three times, and then dried in vacuum. Figure S6 shows the TEM images of MNP-NH2 and CD-MNP. The sizes of them were about 15 nm (Fig. S5a) and around 70 nm from TEM image (Fig. S5b).

Fig. S5. TEM images of magnetic nanoparticles (a) and CD modified magnetic nanoparticles(b).

4. Removal of metal ions

After removal of AD-MAH-RhB by CD-MNP, the supernatant solution was titrated by EDTA. Fig. S6 shows the remaining Hg2+ in the supernatant solutions before and after removal by CD-MNP. The amount of remained Hg2+ was very low, suggesting the Hg ions could be detected by AD-MAH-RhB and removed by CD-MNP.

Fig. S6. Remaining Hg2+ in the supernatant solutions before and after removal of CD-MNP and AD-MAH-RhB-Hg2+ inclusion complex.