Highly Selective and Sensitive Fluorescent Sensing of Oxalate in Water

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1 Supplementary Information for Highly Selective and Sensitive Fluorescent Sensing of in Water Min Hu, Guoqiang Feng* Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 4379, P.R. China, 1. General Experimental Details. Starting materials were purchased from commercial suppliers and were used without further purification. All solvents were purified by the most used methods before use. N-(2-hydroxyethyl)piperazine-N -(2-ethane-sulfonic acid) (HEPES) was used to prepare buffer solution and all solutions were prepared with using distilled water that had been passed through a Millipore-Q ultrapurification system. UV-vis spectra and fluorescent spectra were recorded on an Agilent Cary 1 UV-vis spectrophotometer and an Agilent Cary Eclipse fluorescence spectrophotometer, respectively. 2. Synthesis of Cu 2 L 2 2 OHC 1. CH 3 CN 2. NaBH 4 /CH 3 OH CHO HN HN HN Cu(NO 3 ) 2 CH 3 OH HN N H Cu 2+ H N N H Cu 2+ H N 4NO 3 - L Cu 2 L The macrocycle ligand L can be prepared very easily by [2+2] condensation of terephthaldehyde with diethylenetriamine followed by reduction using NaBH 4 (above scheme). 1 The copper complex Cu 2 L was prepared according to the procedure published by Fabbrizzi et al 2 and was recrystallized from MeOH/H 2 O (v/v, 9:1) to afford the pure compound. Yield: 76%. Elemental analysis calcd for C 24 H 38 N 6 Cu 2 (NO 3 ) 4 H 2 O: C 35.87, H 5.2, N 17.43; found: C 35.93, H 5.32, N References: 1. Chen, D.; Martell, A. E. Tetrahedron 1991, 47, Fabbrizzi, L.; Marcotte, N.; Stomeo, F.; Taglietti, A. Angew. Chem. Int. Ed. 22, 41,

2 3. Job s plot examined for Cu 2 L with fluorescein and Eosin Y I-I (51 nm) [Cu 2 L]/([Cu 2 L] +[Fluorescein]) I-I (54 nm) [Cu 2 L]/([Cu 2 L]+[Eosin Y]) Figure S1. Job s plot examined between Cu 2 L with indicator fluorescein (a) and Eosin Y (b). [Cu2L] + [indicator] = 1 μm. All the spectra were measured in pure aqueous solution of 1 mm HEPES buffer (ph 7.) at UV studies of ensemble 1 on sensing oxalate over other anions Fluorecein (1 M) Ensemble 1 (1 M) Ensemble 1 (1 M) + (1 M).4.35 max = 488 nm Ensemble 1 ( max = 495 nm) Absorbance [] -1 M Wavelength(nm) (a)

3 .4.35 Ensemble 1 + other anions.3 Absorbance Fluorescein Wavelength (nm) (b) Figure S2. (a) UV-vis spectra changes of ensemble 1 (1 μm) upon addition -1 equiv of oxalate (Sodium salt) in pure aqueous solution of 1 mm HEPES buffer (ph 7.) at 25. (b) UV-vis spectra changes of ensemble 1 (1 μm) in the presence of various anions (1 μm) (Sodium salt). Dashed line is the UV-vis spectra of fluorescein (1 μm). All spectra are measured in pure aqueous solution of 1 mm HEPES buffer (ph 7.) at UV studies of ensemble 2 on sensing oxalate over other anions Eosin Y (1 M) Ensemble 2 (1 M) Ensemble 2 (1 M) + (3 M) 1..8 max = 515 nm Ensemble 2 ( max = 522 nm) Absorbance.6.4 [] -1 M Wavelength(nm) (a)

4 Eosin Y Ensemble 2 + other anions Absorbance Wavelength (nm) (b) Figure S3. (a) UV-vis spectra changes of ensemble 2 (1 μm) upon addition -1 equiv of oxalate (Sodium salt). (b) UV-vis spectra changes of ensemble 2 (1 μm) in the presence of various anions (3 μm) (Sodium salt). Dashed line is the UV-vis spectra of Eosin Y (1 μm). All spectra are measured in pure aqueous solution of 1 mm HEPES buffer (ph 7.) at Comparison of fluorescent sensing oxalate with other anions using ensemble 1 and Fluorescent Intensity ensemble 1 + other anions Wavelength(nm) (a)

5 I/I (51 nm) Succinate Glutarate Adipate Acetate Phosphate Perchlorate Bicarbonate Nitrate Sulphate Terephthalate Fumarate Maleate [anion] M (b) 25 Fluorescent Intensity Ensemble 2 + other anions Wavelength(nm) (c)

6 8 I/I (54 nm) Succinate Glutarate Adipate Acetate Perchlorate Nitrate Phosphate Sulphate Bicarbonate Terephthalate Fumarate Maleate [anion] M (d) Figure S4. (a) Fluorescence spectra changes of ensemble 1 (1 μm) upon addition of different anions (1 equiv). (b) A plot of relative fluorescence intensity of ensemble 1 at 51 nm (I/I ) vs concentrations for different anions. (c) Fluorescence spectra changes of ensemble 2 (1 μm) upon addition of different anions (1 equiv). (d) A plot of relative fluorescence intensity of ensemble 2 at 54 nm (I/I ) vs concentrations for different anions. I is the fluorescence intensity of ensemble, I is the fluorescence intensity of ensemble after addition of anions. λ ex for ensemble 1 is 47 nm. λ ex for ensemble 2 is 49 nm. All spectra are measured in pure aqueous solution of 1 mm HEPES buffer (ph 7.) at Determination of the apparent association constants (K a ) for oxalate anion with Cu 2 L

7 (a) 3 Titration of oxalate (-1 M) to ensemble 1 (1 M) 25 2 Model Equation IDA (User) y=y+m2*.5*( (m1+x)-sqrt((m 1-x)^2+4*k*m1 *x))/(1-k) I (51nm) 15 1 Reduced Chi-Sqr Adj. R-Square.9954 Value y m m1 1 k K a1 = M -1, k =.49, then K a2 = M [] (b) 5 45 Titration of oxalate (-1 M) to ensemble 2 (1 M) 4 I (54nm) Model Equation Reduced Chi-Sqr K a1 = M -1, k =.886, then K a2 = M [] M IDA (User) y=y+m2*.5*(( m1+x)-sqrt((m1 -x)^2+4*k*m1*x ))/(1-k) Adj. R-Square.9967 Value y m m1 1 k Figure S5. Curve fitting of the titration date. (a) Titration of oxalate (-1 μm) to ensemble 1 (1 μm). (b) Titration of oxalate (-1 μm) to ensemble 2 (1 μm). 8. Determination of the detection limit: The detection limit DL of ensemble 2 for oxalate was determined from the following equation: DL = K*S b /S Where: K = 3, S b is the standard deviation of the blank solution, which was found to be.64 from ten repeat measurements of the blank solution, S is the slope of the calibration curve.

8 I (54nm) I = [] R 2 = [] M Figure S6. Calibration curve of the fluorescence changes of ensemble 2 (1 μm) upon addition of oxalate (1-5 μm). 9. Sensing oxalate in the presence of other anions I/I Succinate Glutarate Adipate Acetate Terephthalate Maleate Fumarate Phosphate Perchlorate Bicarbonate Nitrate Sulphate (a) Using ensemble 1.

9 6 5 4 I/I Succinate Glutarate Adipate Acetate Terephthalate Maleate Fumarate Phosphate Perchlorate Bicarbonate Nitrate Sulphate (b) Using ensemble 2. Figure S7. The sensing selectivity of ensemble (1 μm) for oxalate in the presence of the appropriate anion (1 μm) of interest in 1 mm HEPES buffer (ph = 7.). I is the fluorescence intensity of ensemble, I is the fluorescence intensity of ensemble after addition of anions. The white bars represent the fluorescence response of ensemble in the presence of the appropriate anion (1 μm) of interest. The red bars represent the fluorescence response upon addition of 1 μm oxalate to a solution of ensemble in the presence of the appropriate anion (1 μm) of interest. (a) ensemble 1 (λ ex = 47 nm, λ em = 51 nm); (b) ensemble 2 (λ ex = 49 nm, λ em = 54 nm). Each experiment was repeated 3-5 times.