Turn-On Fluorescent Sensing of Palladium Species with An ...
Supporting Information:
Fluorogenic and Chromogenic Detection of Palladium Species through a Catalytic Conversion of a Rhodamine B Derivative Mi Eun Jun and Kyo Han Ahn* Department of Chemistry and Center for Electro-Photo Behaviors in Advanced Molecular Systems, POSTECH, San 31 Hyoja-dong, Pohang, 790-784 Republic of Korea [email protected] List of contents 1. Synthesis of probe 1 and formation of benzoxazole 2 ------------------------------------------ S2 2.
1
H and 13C NMR spectra of probe 1 and benzoxazole 2 ---------------------------------------- S4
3. Figure S1. UV/Vis absorption spectra for (a) probe 1 itself and (b) a solution containing probe 1 (10 µM), PdCl2 (1.0 µM), and [(t-Bu)3PH]BF4 (4.0 µM) in acetonitrile at 85 °C after 1 h ------------------------------------------------------------------------------------------------ S5 4. Figure S2. Fluorescence spectra for (a) probe 1 itself and (b) a solution containing probe 1 (10 µM), PdCl2 (1.0 µM), and [(t-Bu)3PH]BF4 (4.0 µM) in acetonitrile at 85 °C after 1 h (excitation at 540 nm) ------------------------------------------------------------------------------- S5 5. Figure S3. Fluorescence enhancement depending on palladium metal sources used ------ S6 6. Figure S4. Fluorescence enhancement data of probe 1 (10 µM) toward PdCl2 (1.0 μM, as the chloride salt) in the presence of [(t-Bu)3PH]BF4 (4.0 μM) in acetonitrile, measured after 1 h at 85 °C (excitation at 540 nm): in the absence (A) and presence (B) of a sulfurcontaining compound (N-Acetyl-L-cysteine, 5 μM)--------------------------------------------- S6 7. Figrue S5. Fluorescence enhancement data of probe 1 (10 µM) toward various metal species (1.0 μM, as the chloride salt) in the presence of [(t-Bu)3PH]BF4 (4.0 μM) in acetonitrile, measured after 1 h at 85 °C (excitation at 540 nm) ------------------------------- S7 8. Figure S6. Fluorescence titration data of probe 1 (10 µM) toward acetic acid (1–5 equiv) in acetonitrile, measured after 1 h at 85 °C (excitation at 540 nm)------------------------------- S7
9. Figure S7. Fluorescence spectra taken for the purified samples containing product 3 (in red) and for the reference samples containing known amount of palladium catalyst [(Ph3P)4Pd] in the range of (a) 1.0 – 300 ppb and (b) 1.0 – 20 ppb, both of which are treated with probe 1 (50 µM) and [(t-Bu)3PH]BF4 (50 µM) in acetonitrile and heated at 85 °C for 1 h (excitation at 540 nm) ----------------------------------------------------------------------------------------------S8 S1
Synthesis of probe 1
Et2N
O
NEt2
CO2
1) POCl3 1,2-Dichloroethane reflux, 4 h 2) 2-Iodoaniline, Et3N Acetonitrile reflux, 4 h
Et2N
O
NEt2
N OI
To a solution of rhodamine B (1.0 g, 2.1 mmol) in dry 1,2-dichloroethane (15 mL) under stirring was added phosphorus oxychloride (1.9 mL, 21 mmol) dropwise over a period of 10 min. After being heated to reflux for 4 h, the solvent and excess amount of phosphorus oxychloride was removed by rotary evaporation to give the corresponding acid chloride, which was dried under high vacuum and used for the next step without further purification. To a solution of the acid chloride in dry acetonitrile (5.0 mL) was added dropwise a solution of 2-iodoaniline (1.8 g, 8.4 mmol) and triethylamine (3.7 mL) in dry acetonitrile (5.0 mL), the resulting mixture was stirred for 5 h at room temperature. The reaction mixture was then concentrated under vacuum, and the residue was purified by column chromatography (ethyl acetate/dichloromethane = 1/5, v/v) to give the crude product, which was further purified by recrystallization
from
dichloromethane/hexane (25:1, v/v) to give a pure compound 1 as a white solid in 87 % yield (1.17 g): mp = 204.8 °C; Rf = 0.81 (ethyl acetate/dichloromethane = 1/5, v/v); 1H NMR (CDCl3, 300 MHz): δ 1.15 (12H, m, J = 7.0 Hz), 3.28–3.36 (8H, m), 6.09 (1H, dd, J = 1.5, 7.9 Hz), 6.17 (1H, d, 2.6 Hz), 6.29 (1H, d, 2.6 Hz), 6.30 (1H, dd, 2.6, 8.8 Hz), 6.37 (1H, dd, J = 2.6, 8.8 Hz), 6.56 (1H, d, J = 8.8 Hz), 6.84 (1H, t, J = 7.7 Hz), 6.89 (1H, d, 8.8 Hz), 7.01 (1H, t, J = 7.7 Hz), 7.28–7.31 (1H, m), 7.53–7.63 (2H, m), 7.72 (1H, d, J = 7.7 Hz), 8.06–8.09 (1H, m); 13C NMR (CDCl3, 300 MHz): δ 12.9, 44.8, 69.2, 97.9, 98.4, 101.0, 105.9, 107.8, 108.4, 108.7, 124.1, 124.8, 128.4, 128.9, 129.1, 129.5, 129.7, 132.6, 132.8, 133.2, 139.4, 140.5, 149.4, 149.5, 151.2, 154.4, 155.1, 165.9; HRMS (EI): m/z calcd. for C34H34IN3O2 [M+] 643.1696; found 643.1693.
S2
Formation of benzoxazole 2 from compound 1
Et2N
O
NEt2
N
PdCl2 [(t-Bu)3PH]BF4 Acetonitrile 85 ℃, 1 h
Et2N
NEt2
O
N O
OI
To a NMR tube containing a solution of o-iodophenylspirolactam 1 (7.6 mg, 11.8 μmol) in CD3CN (0.55 mL) at 85 °C, was added a solution of PdCl2 (1.2 mg, 6.8 μmol) and [(t-Bu)3PH]BF4 (2.7 mg, 9.4 μmol) in CD3CN, and the resulting mixture was kept at the same temperature for 1 h followed by cooling to room temperature, and then it was analyzed by NMR. Spectral data for 2: 1H NMR (CD3CN, 300 MHz): δ 1.24 (12H, t, J = 7.1 Hz), 3.60 (8H, q, J = 7.1 Hz), 6.81 (2H, d, J = 2.5 Hz), 6.89–6.95 (1H, m), 6.96 (1H, d, J = 2.5 Hz), 6.99 (1H, d, J = 2.5 Hz), 7.22–7.29 (4H, m), 7.45–7.48 (1H, m), 7.80–7.86 (3H, m), 8.12-8.15 (1H, m); 13C NMR (CD3CN, 300 MHz) δ (ppm): δ 13.2, 47.1, 95.5, 97.4, 115.0, 115.8, 127.2, 129.3, 129.5, 129.6, 130.3, 131.9, 132.0, 132.9, 133.0, 133.3, 137.3, 140.6, 157.0, 159.2, 159.3, 166.8.
S3
N
O
N
N O I
S4
Absorption and emission spectra of compound 1 0.15
Absorbance
(b)
0.10
0.05 (a)
0.00 450
500
550
600
650
Wavelength (nm) Figure S1. UV/Vis absorption spectra for (a) probe 1 itself and (b) a solution containing probe 1 (10 µM), PdCl2 (1.0 µM), and [(t-Bu)3PH]BF4 (4.0 µM) in acetonitrile at 85 °C after 1 h.
Fl. Intensity (au)
140 120
(b)
100 80 60 40 20 (a)
0 550
600
650
700
750
Wavelength (nm) Figure S2. Fluorescence spectra for (a) probe 1 itself and (b) a solution containing probe 1 (10 µM), PdCl2 (1.0 µM), and [(t-Bu)3PH]BF4 (4.0 µM) in acetonitrile at 85 °C after 1 h (excitation at 540 nm).
S5
Fl. Intensity (au)
Fluorescence enhancement data for three different palladium sources 900 800 700 600 500 400 300 200 100 0
Probe 1 only PdCl2 Pd(OAc)2 Pd2dba3
Probe 1 itself
550
600
650
700
750
Wavelength (nm)
Figure S3. Fluorescence enhancement depending on palladium metal sources used—PdCl2, Pd(OAc)2, and Pd2dba3. Each metal source (1.0 µM) was treated with probe 1 (10 µM) and [(tBu)3PH]BF4 (4.0 µM) and then heated at 85 °C for 1 h before taking the emission spectrum (excitation at 540 nm).
Fl. Intensity (au)
100 80 60 40 20 0
B
A
Figure S4. Fluorescence enhancement data of probe 1 (10 µM) toward PdCl2 (1.0 μM, as the chloride salt) in the presence of [(t-Bu)3PH]BF4 (4.0 μM) in acetonitrile, measured after 1 h at 85 °C (excitation at 540 nm): in the absence (A) and presence (B) of a sulfur-containing compound (N-Acetyl-L-cysteine, 5 μM).
S6
Fl. Intensity (au)
400 without PdCl2
300
with PdCl2
200 100
Pr o
be Pd 1 (ll ) Pt (ll ) Fe (ll ) Fe (ll l) Ni (ll ) M n( ll) Cu (ll ) M g( ll) Cr (ll ) Co (ll ) Zn (ll ) Al (ll l) Al l
0
Figure S5. Fluorescence enhancement data of probe 1 (10 µM) toward various metal species (1.0 μM, as the chloride salt) in the presence of [(t-Bu)3PH]BF4 (4.0 μM) in acetonitrile, measured after 1 h at 85 °C (excitation at 540 nm): The black columns indicated with blue arrows are those obtained only in the presence of the metal species indicated, the grey columns indicates those obtained in the presence of both the specified metal species and PdCl2, and the column noted as “All” means the enhancement data in the presence of all the metal species together.
Fl. Intensity (au)
200 0 equiv. 1 equiv. 3 equiv. 5 equiv.
150 100 50 0
550
600
650
700
Wavelength (nm) Figure S6. Fluorescence titration data of probe 1 (10 µM) toward acetic acid (1–5 equiv) in acetonitrile, measured after 1 h at 85 °C (excitation at 540 nm).
S7
Determination of residual palladium contents with probe 1 Experimental procedure. Stock solutions of probe 1 (2.0 mM), compound 3 (10.0 mM), and [(t-Bu)3PH]BF4 (5.0 mM) were prepared in acetonitrile. A sealed vial containing probe 1 (75 μL, 2.0 mM), compound 3 purified (1.5 mL. 10.0 mM, 3.84 mg), and [(tBu)3PH]BF4 (30 μL, 5.0 mM) was immersed in an oil bath that was preheated at 85 °C, which was kept for 1 h. The vial was then cooled to room temperature using ice-water, and transferred to a cuvette using acetonitrile to give a final volume of 3.0 mL for the fluorescence measurement.
To obtain the standard curve between the fluorescence intensity versus the concentration of the palladium catalyst, the known amount of (Ph3P)4Pd (300, 100, 50, 20, 10, and 2 ppb) in acetonitrile was treated with probe 1 and [(t-Bu)3PH]BF4 similarly as above, and its emission spectrum was recorded separately. Calculation of the palladium content in the sample compound 3 purified by the column chromatography. The compound 3 was purified by column chromatography on silica gel (30 g) using ethylacetate/n-hexane (1/4, by volumne) as the eluant to give the 1st purified sample. This purified sample was subjected to the same column chromatography (30 g SiO2) to give the 2nd purified sample, which was further purified in the same way to give the 3rd purified sample. From the fluorescence data in Figure S4, the 1st purified sample shows intensity equivalent to 180 ppb of (PPh3)4Pd. Accounting the weight of the solvent used (3.0 mL of acetonitrile = 2.358 g), the corresponding weight of (PPh3)4Pd is 4.24 × 10–7 g which contains 3.91 × 10–8 g of palladium. Therefore, the palladium content in the 3.84 mg of the 1st purified sample is 10.2 ppm (3.91 × 10–8 g palladium in 3.84 mg sample). The palladium contents in the 2nd and the 3rd purified samples are determined in the same way, resulting in 960 and 110 ppb, respectively. In these calculations, a slight loss of the sample during the column chromatography was ignored.
(a) Fl. Intensity (au)
Fl. Intensity (au)
300 300
250 200 150
1st
100
350 300 250 200 150 100 50 0
1st
180 ppb
0
100 50
50
100 200 300 [Pd(PPh 3 )4] (ppb)
0 550
600
650
Wavelength (nm)
S8
700
(b) 15
10
Fl. Intensity (au)
Fl. Intensity (au)
20 2nd 10
5 3rd 2
0 probe 1 550
16 14 12 10 8 6 4 2 0
2nd
3rd 2 ppb
0
17 ppb
5 10 15 20 [Pd(PPh3)4] (ppb)
1
600
650
700
Wavelength (nm) Figure S7. Fluorescence spectra taken for the purified samples containing product 3 (in red) and for the reference samples containing known amount of palladium catalyst [(Ph3P)4Pd] in the range of (a) 1.0 – 300 ppb and (b) 1.0 – 20 ppb, both of which are treated with probe 1 (50 µM) and [(t-Bu)3PH]BF4 (50 µM) in acetonitrile and heated at 85 °C for 1 h (excitation at 540 nm). The Arabic numbers indicate the content of the palladium catalyst of each known sample in ppb unit; the “1st", “2nd", and “3rd" indicate the samples of product 3 that are purified by column chromatography on silica gel once, twice, and three times respectively. The inset shows the plot of fluorescence intensity depending on the concentration of the palladium source.
S9
Fluorogenic and Chromogenic Detection of Palladium Species through a Catalytic Conversion of a Rhodamine B Derivative Mi Eun Jun and Kyo Han Ahn* Department of Chemistry and Center for Electro-Photo Behaviors in Advanced Molecular Systems, POSTECH, San 31 Hyoja-dong, Pohang, 790-784 Republic of Korea [email protected] List of contents 1. Synthesis of probe 1 and formation of benzoxazole 2 ------------------------------------------ S2 2.
1
H and 13C NMR spectra of probe 1 and benzoxazole 2 ---------------------------------------- S4
3. Figure S1. UV/Vis absorption spectra for (a) probe 1 itself and (b) a solution containing probe 1 (10 µM), PdCl2 (1.0 µM), and [(t-Bu)3PH]BF4 (4.0 µM) in acetonitrile at 85 °C after 1 h ------------------------------------------------------------------------------------------------ S5 4. Figure S2. Fluorescence spectra for (a) probe 1 itself and (b) a solution containing probe 1 (10 µM), PdCl2 (1.0 µM), and [(t-Bu)3PH]BF4 (4.0 µM) in acetonitrile at 85 °C after 1 h (excitation at 540 nm) ------------------------------------------------------------------------------- S5 5. Figure S3. Fluorescence enhancement depending on palladium metal sources used ------ S6 6. Figure S4. Fluorescence enhancement data of probe 1 (10 µM) toward PdCl2 (1.0 μM, as the chloride salt) in the presence of [(t-Bu)3PH]BF4 (4.0 μM) in acetonitrile, measured after 1 h at 85 °C (excitation at 540 nm): in the absence (A) and presence (B) of a sulfurcontaining compound (N-Acetyl-L-cysteine, 5 μM)--------------------------------------------- S6 7. Figrue S5. Fluorescence enhancement data of probe 1 (10 µM) toward various metal species (1.0 μM, as the chloride salt) in the presence of [(t-Bu)3PH]BF4 (4.0 μM) in acetonitrile, measured after 1 h at 85 °C (excitation at 540 nm) ------------------------------- S7 8. Figure S6. Fluorescence titration data of probe 1 (10 µM) toward acetic acid (1–5 equiv) in acetonitrile, measured after 1 h at 85 °C (excitation at 540 nm)------------------------------- S7
9. Figure S7. Fluorescence spectra taken for the purified samples containing product 3 (in red) and for the reference samples containing known amount of palladium catalyst [(Ph3P)4Pd] in the range of (a) 1.0 – 300 ppb and (b) 1.0 – 20 ppb, both of which are treated with probe 1 (50 µM) and [(t-Bu)3PH]BF4 (50 µM) in acetonitrile and heated at 85 °C for 1 h (excitation at 540 nm) ----------------------------------------------------------------------------------------------S8 S1
Synthesis of probe 1
Et2N
O
NEt2
CO2
1) POCl3 1,2-Dichloroethane reflux, 4 h 2) 2-Iodoaniline, Et3N Acetonitrile reflux, 4 h
Et2N
O
NEt2
N OI
To a solution of rhodamine B (1.0 g, 2.1 mmol) in dry 1,2-dichloroethane (15 mL) under stirring was added phosphorus oxychloride (1.9 mL, 21 mmol) dropwise over a period of 10 min. After being heated to reflux for 4 h, the solvent and excess amount of phosphorus oxychloride was removed by rotary evaporation to give the corresponding acid chloride, which was dried under high vacuum and used for the next step without further purification. To a solution of the acid chloride in dry acetonitrile (5.0 mL) was added dropwise a solution of 2-iodoaniline (1.8 g, 8.4 mmol) and triethylamine (3.7 mL) in dry acetonitrile (5.0 mL), the resulting mixture was stirred for 5 h at room temperature. The reaction mixture was then concentrated under vacuum, and the residue was purified by column chromatography (ethyl acetate/dichloromethane = 1/5, v/v) to give the crude product, which was further purified by recrystallization
from
dichloromethane/hexane (25:1, v/v) to give a pure compound 1 as a white solid in 87 % yield (1.17 g): mp = 204.8 °C; Rf = 0.81 (ethyl acetate/dichloromethane = 1/5, v/v); 1H NMR (CDCl3, 300 MHz): δ 1.15 (12H, m, J = 7.0 Hz), 3.28–3.36 (8H, m), 6.09 (1H, dd, J = 1.5, 7.9 Hz), 6.17 (1H, d, 2.6 Hz), 6.29 (1H, d, 2.6 Hz), 6.30 (1H, dd, 2.6, 8.8 Hz), 6.37 (1H, dd, J = 2.6, 8.8 Hz), 6.56 (1H, d, J = 8.8 Hz), 6.84 (1H, t, J = 7.7 Hz), 6.89 (1H, d, 8.8 Hz), 7.01 (1H, t, J = 7.7 Hz), 7.28–7.31 (1H, m), 7.53–7.63 (2H, m), 7.72 (1H, d, J = 7.7 Hz), 8.06–8.09 (1H, m); 13C NMR (CDCl3, 300 MHz): δ 12.9, 44.8, 69.2, 97.9, 98.4, 101.0, 105.9, 107.8, 108.4, 108.7, 124.1, 124.8, 128.4, 128.9, 129.1, 129.5, 129.7, 132.6, 132.8, 133.2, 139.4, 140.5, 149.4, 149.5, 151.2, 154.4, 155.1, 165.9; HRMS (EI): m/z calcd. for C34H34IN3O2 [M+] 643.1696; found 643.1693.
S2
Formation of benzoxazole 2 from compound 1
Et2N
O
NEt2
N
PdCl2 [(t-Bu)3PH]BF4 Acetonitrile 85 ℃, 1 h
Et2N
NEt2
O
N O
OI
To a NMR tube containing a solution of o-iodophenylspirolactam 1 (7.6 mg, 11.8 μmol) in CD3CN (0.55 mL) at 85 °C, was added a solution of PdCl2 (1.2 mg, 6.8 μmol) and [(t-Bu)3PH]BF4 (2.7 mg, 9.4 μmol) in CD3CN, and the resulting mixture was kept at the same temperature for 1 h followed by cooling to room temperature, and then it was analyzed by NMR. Spectral data for 2: 1H NMR (CD3CN, 300 MHz): δ 1.24 (12H, t, J = 7.1 Hz), 3.60 (8H, q, J = 7.1 Hz), 6.81 (2H, d, J = 2.5 Hz), 6.89–6.95 (1H, m), 6.96 (1H, d, J = 2.5 Hz), 6.99 (1H, d, J = 2.5 Hz), 7.22–7.29 (4H, m), 7.45–7.48 (1H, m), 7.80–7.86 (3H, m), 8.12-8.15 (1H, m); 13C NMR (CD3CN, 300 MHz) δ (ppm): δ 13.2, 47.1, 95.5, 97.4, 115.0, 115.8, 127.2, 129.3, 129.5, 129.6, 130.3, 131.9, 132.0, 132.9, 133.0, 133.3, 137.3, 140.6, 157.0, 159.2, 159.3, 166.8.
S3
N
O
N
N O I
S4
Absorption and emission spectra of compound 1 0.15
Absorbance
(b)
0.10
0.05 (a)
0.00 450
500
550
600
650
Wavelength (nm) Figure S1. UV/Vis absorption spectra for (a) probe 1 itself and (b) a solution containing probe 1 (10 µM), PdCl2 (1.0 µM), and [(t-Bu)3PH]BF4 (4.0 µM) in acetonitrile at 85 °C after 1 h.
Fl. Intensity (au)
140 120
(b)
100 80 60 40 20 (a)
0 550
600
650
700
750
Wavelength (nm) Figure S2. Fluorescence spectra for (a) probe 1 itself and (b) a solution containing probe 1 (10 µM), PdCl2 (1.0 µM), and [(t-Bu)3PH]BF4 (4.0 µM) in acetonitrile at 85 °C after 1 h (excitation at 540 nm).
S5
Fl. Intensity (au)
Fluorescence enhancement data for three different palladium sources 900 800 700 600 500 400 300 200 100 0
Probe 1 only PdCl2 Pd(OAc)2 Pd2dba3
Probe 1 itself
550
600
650
700
750
Wavelength (nm)
Figure S3. Fluorescence enhancement depending on palladium metal sources used—PdCl2, Pd(OAc)2, and Pd2dba3. Each metal source (1.0 µM) was treated with probe 1 (10 µM) and [(tBu)3PH]BF4 (4.0 µM) and then heated at 85 °C for 1 h before taking the emission spectrum (excitation at 540 nm).
Fl. Intensity (au)
100 80 60 40 20 0
B
A
Figure S4. Fluorescence enhancement data of probe 1 (10 µM) toward PdCl2 (1.0 μM, as the chloride salt) in the presence of [(t-Bu)3PH]BF4 (4.0 μM) in acetonitrile, measured after 1 h at 85 °C (excitation at 540 nm): in the absence (A) and presence (B) of a sulfur-containing compound (N-Acetyl-L-cysteine, 5 μM).
S6
Fl. Intensity (au)
400 without PdCl2
300
with PdCl2
200 100
Pr o
be Pd 1 (ll ) Pt (ll ) Fe (ll ) Fe (ll l) Ni (ll ) M n( ll) Cu (ll ) M g( ll) Cr (ll ) Co (ll ) Zn (ll ) Al (ll l) Al l
0
Figure S5. Fluorescence enhancement data of probe 1 (10 µM) toward various metal species (1.0 μM, as the chloride salt) in the presence of [(t-Bu)3PH]BF4 (4.0 μM) in acetonitrile, measured after 1 h at 85 °C (excitation at 540 nm): The black columns indicated with blue arrows are those obtained only in the presence of the metal species indicated, the grey columns indicates those obtained in the presence of both the specified metal species and PdCl2, and the column noted as “All” means the enhancement data in the presence of all the metal species together.
Fl. Intensity (au)
200 0 equiv. 1 equiv. 3 equiv. 5 equiv.
150 100 50 0
550
600
650
700
Wavelength (nm) Figure S6. Fluorescence titration data of probe 1 (10 µM) toward acetic acid (1–5 equiv) in acetonitrile, measured after 1 h at 85 °C (excitation at 540 nm).
S7
Determination of residual palladium contents with probe 1 Experimental procedure. Stock solutions of probe 1 (2.0 mM), compound 3 (10.0 mM), and [(t-Bu)3PH]BF4 (5.0 mM) were prepared in acetonitrile. A sealed vial containing probe 1 (75 μL, 2.0 mM), compound 3 purified (1.5 mL. 10.0 mM, 3.84 mg), and [(tBu)3PH]BF4 (30 μL, 5.0 mM) was immersed in an oil bath that was preheated at 85 °C, which was kept for 1 h. The vial was then cooled to room temperature using ice-water, and transferred to a cuvette using acetonitrile to give a final volume of 3.0 mL for the fluorescence measurement.
To obtain the standard curve between the fluorescence intensity versus the concentration of the palladium catalyst, the known amount of (Ph3P)4Pd (300, 100, 50, 20, 10, and 2 ppb) in acetonitrile was treated with probe 1 and [(t-Bu)3PH]BF4 similarly as above, and its emission spectrum was recorded separately. Calculation of the palladium content in the sample compound 3 purified by the column chromatography. The compound 3 was purified by column chromatography on silica gel (30 g) using ethylacetate/n-hexane (1/4, by volumne) as the eluant to give the 1st purified sample. This purified sample was subjected to the same column chromatography (30 g SiO2) to give the 2nd purified sample, which was further purified in the same way to give the 3rd purified sample. From the fluorescence data in Figure S4, the 1st purified sample shows intensity equivalent to 180 ppb of (PPh3)4Pd. Accounting the weight of the solvent used (3.0 mL of acetonitrile = 2.358 g), the corresponding weight of (PPh3)4Pd is 4.24 × 10–7 g which contains 3.91 × 10–8 g of palladium. Therefore, the palladium content in the 3.84 mg of the 1st purified sample is 10.2 ppm (3.91 × 10–8 g palladium in 3.84 mg sample). The palladium contents in the 2nd and the 3rd purified samples are determined in the same way, resulting in 960 and 110 ppb, respectively. In these calculations, a slight loss of the sample during the column chromatography was ignored.
(a) Fl. Intensity (au)
Fl. Intensity (au)
300 300
250 200 150
1st
100
350 300 250 200 150 100 50 0
1st
180 ppb
0
100 50
50
100 200 300 [Pd(PPh 3 )4] (ppb)
0 550
600
650
Wavelength (nm)
S8
700
(b) 15
10
Fl. Intensity (au)
Fl. Intensity (au)
20 2nd 10
5 3rd 2
0 probe 1 550
16 14 12 10 8 6 4 2 0
2nd
3rd 2 ppb
0
17 ppb
5 10 15 20 [Pd(PPh3)4] (ppb)
1
600
650
700
Wavelength (nm) Figure S7. Fluorescence spectra taken for the purified samples containing product 3 (in red) and for the reference samples containing known amount of palladium catalyst [(Ph3P)4Pd] in the range of (a) 1.0 – 300 ppb and (b) 1.0 – 20 ppb, both of which are treated with probe 1 (50 µM) and [(t-Bu)3PH]BF4 (50 µM) in acetonitrile and heated at 85 °C for 1 h (excitation at 540 nm). The Arabic numbers indicate the content of the palladium catalyst of each known sample in ppb unit; the “1st", “2nd", and “3rd" indicate the samples of product 3 that are purified by column chromatography on silica gel once, twice, and three times respectively. The inset shows the plot of fluorescence intensity depending on the concentration of the palladium source.
S9
