Supporting Information

Transcription

1 Supporting Information Cyclodextrin Supramolecular Complex as Water Soluble Ratiometric Sensor for ferric Ion Sensing Meiyun Xu, Shuizhu Wu,* Fang Zeng, Changmin Yu College of Materials Science & Engineering, South China University of Technology, Guangzhou , China and State Key Laboratory of Pulp & Paper Engineering, South China University of Technology, Guangzhou , China S1

2 1. Schemes, spectra and figures H H H H H H H H H H H H H H H H H H + TS-Cl 3 a TS 3 PPh 3 H β-cd-ds S dansyl chloride H 2 Scheme S1. Synthesis route for β-cd-ds. S2

3 H Diethylenetriamine CH 3 H H H 2 SRhB CH + H DCC C AD-HS H H 2 H H C + AD-SRhB Scheme S2. Synthesis route for AD-SRhB. S3

4 Figure S1. Mass spectrum of SRhB. m/z [SRhB + H] S4

5 Figure S2. Mass spectrum of AD-SRhB. m/z [AD-SRhB + H] S5

6 Figure S3. Mass spectrum of β-cd-ds. m/z [β-cd-ds + H] S6

7 Figure S4. 1 H MR spectrum of SRhB S7

8 Figure S5. 1 H MR spectrum of AD-SRhB. 5 S8

9 Figure S6. 1 H MR spectrum of β-cd-ds. S9

10 0.6 Absorbance λ (nm) Figure S7. Absorption spectra of the AD-SRhB/β-CD-DS supramolecular-complex aqueous solution in the absence of ferric ion. S10

11 Figure S8. Photographs of the AD-SRhB/β-CD-DS supramolecular-complex aqueous solution ( M) in the presence and absence of various metal ions ( M) under ambient light (absorption change) and under UV light (fluorescence change). S11

12 6 I 587 / I I 587 / I C / μm x x x x x10-4 C (M) Figure S9. Fluorescence intensity changes (I 587 /I 530 ) for the AD-SRhB/β-CD-DS supramolecular-complex aqueous solution as the concentration of ferric ion was increased. The inset display the I 587 /I 530 values at low ferric ion concentrations (from 0, , , , to M). (ph = 7.0) S12

13 5x10 3 Intensity (counts) 4x10 3 3x10 3 2x10 3 1x Time (ns) Figure S10. Fluorescence decay curves measured for the AD-SRhB/β-CD-DS supramolecular-complex aqueous solution. Black curve: in the absence of Fe 3+ ; red curve: in the presence of Fe 3+ ( M). λ ex = 410 nm, λ em = 530 nm (donor). In the absence of Fe 3+ : τ = ns, χ 2 = In the presence of Fe 3+ : τ = 5.15 ns, χ 2 = S13

14 2.5x x10-2 1/(F t -F f ) 1.5x x x x x x x10 5 1/[β-CD-DS] Figure S11. The relationship curve of 1/(F t F f ) and 1/[β-CD-DS]. (R = ) In the absence of ferric ion, both AD-SRhB and the AD-SRhB/β-CD-DS supramolecular complex did not exhibit fluorescence characteristic of rhodamine B. In the presence of ferric ion, AD-SRhB/Fe 3+ exhibited fluorescence at 587 nm which is characteristic of rhodamine B; and in the supramolecular system, AD-SRhB/Fe 3+ was incorporated inside the cavity of cyclodextrin via the adamantyl group. Therefore we measured the binding constant for the AD-SRhB/β-CD-DS system in the presence of ferric ion. F t is the total fluorescence intensity at 587 nm (λexc = 410 nm) of the solution containing AD-SRhB and β-cd-ds in the presence of Fe 3+ ( M), F f is the fluorescence intensity when the entire amount of AD-SRhB/Fe 3+ is unbound or free, S14

15 i.e. at the very beginning of the experiment before any β-cd-ds is added, while F b corresponds to the case when all AD-SRhB/Fe 3+ is bound to β-cd-ds = + ( F F ) { K[ β CD DS)( F F )} ( F F ) t f b f b f According to the equation, if the system has a 1/1 stoichiometry, then a plot of the experimental data in the form 1/(F t - F f ) vs 1/[β-CD-DS] will produce a straight line, the intercept of which with the 1/(F t - F f ) axis will be 1/(F b - F f ) and its slope will be 1/[K(F b - F f )], whereas the equilibrium constant K will be equal to the ratio intercept/slope. The binding constant (equilibrium constant) is determined to be M -1. (G. Pistolis, Angelos Malliaris, J. Phys. Chem. 1996, 100, ) S15

16 Figure S12. Mass spectrum of Benzene-SRhB. m/z [M+H] S16

17 Figure S13. 1 H MR spectrum of Benzene-SRhB. S17

18 Intensity (a.u.) Fe 3+ 1x10-4 M 9x10-5 M 7x10-5 M 5x10-5 M 3x10-5 M 1x10-5 M 0 M λ (nm) Figure S14. Fluorescence spectra of the Benzene-SRhB/β-CD-DS supramolecular-complex solution upon addition of ferric ion. (ph = 7.0) Compared with that in AD-SRhB/β-CD-DS system, the Benzene-SRhB/Fe 3+ in this complex system could not efficiently quench the fluorescence emission of dansyl, suggesting some of the acceptors (Benzene-SRhBs) were not within the effective energy transfer distance. Probably some of the ion-recognition element Benzene-SRhB moved out of the cyclodextrin cavity, since phenyl group is much smaller compared with adamantyl groups and can move in and out the cyclodextrin cavity easily. S18

19 5 I/I 0 at 587 nm Fe 3+ Cr 3+ Zn 2+ Ag + Ca 2+ Cd 2+ Co 2+ K + Hg 2+ Mn 2+ i 2+ Mg 2+ Cu 2+ Figure S15. Fluorescence intensity changes (I/I 0 at 587 nm) of the AD-SRhB/β-CD-DS supramolecular-complex aqueous solution ( M) in the presence of various metal ions respectively ( M) (λexc = 410 nm, I: fluorescence intensity in the presence of metal ion, I 0 : fluorescence intensity in the absence of metal ion). S19

20 2. Calculation of Förster Critical Radius (R 0 ) [1,3,4] Determination of fluorescence quantum yield The quantum yield can be described as follows: F A ( nd ) ( ) D S Φ D =Φ S FS AD ns Where Φ s is the fluorescence quantum yield of the standard (rhodamine B in ethanol, 0.65, 25 C) [2], F D and F S are the integral area of fluorescence intensity of the chromophore and the standard at the same excitation wavelength, respectively; A D and A S are the absorbance of the chromophore and the standard at the defined excitation wavelength, respectively; n S and n D are the refractive index at 25 C of the solvent of standard (ethanol) and that of chromophore, respectively. 2 2 Calculation of the Förster radii (R0) [1,3,4] The Förster s distance or critical distance R 0 is the characteristic distance, at which the efficiency of energy transfer is 50%. The magnitude of R 0 is dependent on the spectral properties of the donor and the acceptor molecules. If the wavelength λ is expressed in nanometers, then J(λ) is in units of M -1 cm -1 nm 4 and the Förster distance, R 0 in angstroms (Å), is expressed as follows [Eq. (1)]: 2 4 [ κ Φ n J ( ] 1/ 6 R D 0 = λ) [Eq. (1)] Κ 2 is the orientation factor for the emission and absorption dipoles and its value depends on their relative orientation, n is the refractive index of the medium and Φ D is the quantum yield of the donor. J(λ) is the overlap integral of the fluorescence S20

21 emission spectrum of the donor and the absorption spectrum of the acceptor [Eq. (2)]. J λ = 4 ( ) F ( λ) ε ( λ) λ dλ [Eq. (2)] 0 D A F D (λ) is the fluorescence intensity of the donor in the absence of acceptor F D 0 normalized so that ( λ) dλ = 1 ; ε A (λ) is molar extinction coefficient of the acceptor, λ is wavelength. In the current experimental conditions, the Förster distance (R 0 ) has been calculated assuming random orientation of the donor and acceptor molecules taking Κ 2 = 2/3. By using a commercial software rigin 8.0 as the integral tool, we calculated R 0 =29.9 Å for the AD-SRhB/β-CD-DS supramolecular-complex aqueous solution. Hence, energy transfer will be effective for Å d Å (R 0 ± 50% R 0 ) [5]. ormalized intensity (a.u.) λ (nm) Absorbance Figure S16. Fluorescence spectrum of dansyl moiety (donor) on β-cyclodextrin, and absorption spectrum of the open-ring AD-SRhB (acceptor) inside cyclodextrin S21

22 dextrin cavity (ferric ion concentration M). Reference [1]. F. Gouanvé, T. Schuster, E. Allard, R. Méallet-Renault, C. Larpent, Adv. Funct. Mater. 2007, 17, [2]. R.F. Kubin, A.. Fletcher, J. Lumin. 1982, 27, [3]. J. R. Lakowicz, Principles of Fluorescence Spectroscopy; Plenum: ew York, [4]. B. Valeur in Molecular Fluorescence: principles and applications, Wiley-VCH: Weinheim, ew York, [5]. K. E. Sapsford, L. Berti, and I. L. Medintz, Angew. Chem. Int. Ed., 2006, 45, Table S1. Spectroscopic data. Sample λ abs (nm) λ em (nm) [a] Φ f R 0 (nm) Without Fe (spirolactam state) Without with Fe (open-ring state) [a] λ ex = 410 nm. S22