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Supporting Information
Spirolactonized Si-rhodamine: a novel NIR fluorophore
utilized as a platform to construct Si-rhodamine-based
probes
Ting Wang[a], Qing-Jie Zhao[a], Hong-Gang Hu[a], Shi-Chong Yu, Xiang Liu[b], Li
Liu[b]*, Qiu-Ye Wu[a]*
[a]Department of Organic Chemistry, College of Pharmacy
Second Military Medical University Guohe Road 325, Shanghai 200433 (China)
Fax: (+)86-21-81871225 E-mail: [email protected]
[b]State Key Laboratory of New drug and Pharmaceutical Process
Center for Pharmacological Evaluation and Research Shanghai Institute of Pharmaceutical Industry
Zhongshanbeiyi Road 1111, Shanghai 200437 (P.R. China) Fax: (+86)-21-65449361
E-mail: [email protected]
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General Methods. Materials. General chemicals were of the best grade available, supplied by Shanghai Chemical Reagent Co., Shanghai Aladdin reagent Co., Tokyo Chemical Industries (TCI), J&K chemical LTD. and Acros Organics, and were used without further purification. All solvents were used after appropriate distillation or purification.
Apparatus. All reactions were monitored by thin-layer chromatography (TLC) on gel F254 plates. Flash chromatography was carried out on silica gel (200-300 mesh; Qingdao Ocean Chemicals). NMR spectra were recorded on a Bruker AC-300P spectrometer at 300 MHz for 1H NMR and at 75 MHz for 13C NMR. Spectral data are reported in ppm relative to tetramethylsilane (TMS) as internal standard. Mass spectra (MS) were measured with an API-3000 MS spectrometer using electrospray ionization (ESI). High-resolution mass spectra (HRMS) were recorded on an Aglilent Technologies 6538 UHD Accurate-Mass Q-TOF MS spectrometer using ESI. All pH measurements were performed with a pH-3c digital pH-meter (Shanghai Lei Ci Device Works, Shanghai, China) with a combined glass-calomel electrode. UV-visible spectra were obtained on a Shimadzu UV-2450 UV-vis spectrophotometer (Shimadzu, Japan). Fluorescence spectroscopic studies were performed on a Hitachi F-7000. Fluorescence images were obtained using Nikon Eclipse Ti fluorescence microscopy. Pictures were obtained using Sony DSC-TX9 Digital Camera. The refractive index (n) of the solution was measured on Abbe refractometer. The X-ray single crystal diffraction was collected on Bruker APEX DUO diffractometers.
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Absorption Analysis. Absorption spectra were obtained with 1.0-cm glass cells. The The Si-rhodamines (1 mL, 100 µM, dissolved in acetonitrile) was added to a 5.0-mL color comparison tube. Then an appropriate volume of metal ions was added. After dilution to 20.0 µM with 20 mM HEPES buffers at pH = 7.4. The mixture was equilibrated for 30 min before measurement. Fluorescence Analysis. Fluorescence emission spectra were obtained with a Xenon lamp and 1.0-cm quartz cells. The Si-rhodamines (1 mL, 25 µM, dissolved in acetonitrile) was added to a 5.0-mL color comparison tube. Then an appropriate volume of metal ions was added, after dilution to 5.0 µM with 20 mM HEPES buffers at various pH values. For recognizing metal ions, an appropriate volume of metal ions was added. After dilution to 5.0 µM with 20 mM HEPES buffers at pH = 7.4. The mixture was equilibrated for 30 min before measurement. The fluorescence intensity was measured at 520 and 620 nm for Rhodamines and Si-rhodamines, respectively. The excitation and emission slits were set to 10.0 and 10.0 nm, respectively. Relative fluorescence quantum efficiency was obtained by comparing the area under the emission spectrum of the test sample with that of a solution of Cresyl violet in MeOH, which has a quantum efficiency of 0.54. Imaging of SH-SY5Y Cells Incubated with SiR1. SH-SY5Y cells were cultured in culture media (DMEM supplemented with 10% FBS, 50 unit/mL of penicillin, and 50 ug/mL of streptomycin) at 37°C in a humidified incubator, and culture media were replaced with fresh media every day. SH-SY5Y cells were seeded in a 6-well plate in culture media. After 36 h, the cells were incubated with 50 uM SiR (1% DMSO) in culture media for 10 min at 37°C and washed with PBS to remove the remaining SiR. Imaging of SH-SY5Y Cells Incubated with Mercury Ions and SiR-Hg1. SH-SY5Y cells ere cultured in culture media (DMEM supplemented with 10% FBS, 50 unit/mL of penicillin, and 50 ug/mL of streptomycin) at 37°C in a humidified incubator, and culture media were replaced with fresh media every day. SH-SY5Y cells were seeded in a 6-well plate in culture media. After 36 h, the cells were incubated with 50 uM SiR-Hg (1% DMSO) in culture media for 10 min at 37°C. After washing with PBS to remove the remaining SiR-Hg, the treated cells were incubated with 50 uM Hg2+ in culture media for 10 min at 37°C.
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X-Ray crystallography. Single crystals of SiR-Hg were obtained by slow evaporation of dichloromethane/petroleum ether solution SiR-Hg at room temperature, respectively. The X-ray single crystal diffraction data for SiR-Hg were collected on Bruker APEX DUO diffractometers with Mο Kα radiation (λ = 0.71073 Å) at 113 ± 2 K in the ω-2θ scanning mode. The structures were solved by direct methods using the SHELXS-97 program2 and refined by full-matrix least-squares techniques (SHELXL-97) on F2. Anisotropic thermal parameters were assigned to all non-hydrogen atoms. The organic hydrogen atoms were generated geometrically. CCDC-876103 (SiR-Hg) contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystatllographic Data Ceter via www.ccdc.cam.ac.uk/data_request/cif.
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Synthetic procedures and characterizations.
3-bromo-N,N-diethylaniline (2)3. To a suspension of NaH (5.0 g, 60% dispersion in mineral oil, 125 mmol) in THF (100 ml) at 0 °C was added 3-bromoaniline (8.6 g, 50 mmol) under argon. The reaction mixture was stirred for 0.5 h at the same temperature. After iodoethane (19.5 g, 125 mmol) was added, the mixture was stirred at room temperature for 24 h. The reaction was quenched with water carefully, and organic materials were extracted with CH2Cl2 three times. The combined extracts were washed with brine and dried over Na2SO4. After removal of the solvent under reduced pressure, the residue was purified by column chromatography on silica gel (dichloromethane : petroleum ether = 1 : 10) to give product 2 as a discoloured oil (8.3 g, 73% yield). MS (ESI): m/z 228.1 [M+H]+ 228.0. 4,4'-methylenebis(3-bromo-N,N-diethylaniline) (3)4. To a solution of compound 2 (5.7 g, 25 mmol) in AcOH (80 mL) was added 37% formaldehyde (3.75 g, 125 mmol), and the mixture was stirred at 80 °C for 75 min. After cooling to room temperature, the reaction mixture was carefully neutralized with saturated NaHCO3 aq. and NaOH aq. and extracted with CH2Cl2. The organic layer was washed with brine and dried over Na2SO4. After removal of the solvent under reduced pressure, the residue was purified by column chromatography on silica gel (dichloromethane : petroleum ether = 1 : 4) to give pure 3 as a white solid (4.5 g, 77% yield). MS (ESI): m/z 467.3 [M+H]+ 467.1; 1H NMR (300 MHz, CDCl3): δ 1.16 (t, 12H, J = 6.91 Hz), 3.31 (q, 8H, J = 7.07 Hz), 3.98 (s, 2H), 6.54 (d, 2H, J = 8.29 Hz), 6.84(s, 2H), 6.88 (d, 2H, J = 6.29 Hz); 13C NMR (75 MHz,CDCl3): δ 12.5, 39.7, 44.3, 111.1, 115.3, 125.8, 126.0, 130.9, 147.2 Si-Xanthone (SiX)4. To a dried flask flushed with argon, compound 3 (2.3 g, 5.0 mmol) and anhydrous THF (20 mL) were added. The solution was cooled to –78 °C, 1.3 M sec-BuLi in (10.7 mL, 14 mmol) was added, and the mixture was stirred for 0.5 h. At the same temperature, a solution of SiMe2Cl2 (10 mmol) in anhydrous THF (10 mL) was slowly added, and the mixture was slowly warmed to room temperature, then stirred for 6 h. The reaction was quenched by addition of 2 N HCl aq., then the
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mixture was neutralized with NaHCO3, and extracted with CH2Cl2. The organic layer was washed with brine and dried over Na2SO4. The solvent was removed under reduced pressure and the crude 4 was used without further purification. To a solution compound 4 in acetone (50 mL) at 0 °C was added KMnO4 (2.4 g, 15 mmol) in small portions over a period of 1 h with stirring. The mixture was stirred for another 1 h at the same temperature, then diluted with CH2Cl2 (50 mL), filtered through paper filter and evaporated to dryness. The residue was purified by column chromatography on silica gel (dichloromethane : ethyl acetate = 40 : 1) to give pure SiX as a yellow solid (0.36 g, 19% yield). And the product was further recrystallized form dichloromethane/petroleum ether to give SiX as yellow crystals. MS (ESI): m/z 381.8 [M+H]+ 381.2; 1H NMR (300 MHz, CDCl3): δ 0.48 (s, 6H), 1.25 (t, 12H, J = 7.08 Hz) 3.34 (q, 8H, J = 7.08 Hz), 6.78(s, 2H), 6.81 (d, 2H, J = 9.00 Hz), 8.40 (d, 2H, J = 8.98 Hz); 13C NMR (75 MHz, CDCl3): δ -1.1, 12.6, 44.4, 112.6, 113.7, 128.9, 131.8, 140.5, 149.0, 184.8.
iodobenzoyl chloride (6). To a solution of 2-iodobenzoic acid (5.58 g, 22.5 mmol) in CH2Cl2 (50 mL) was added a drop DMF. The solution was cooled to 0 °C, then oxalyl chloride (2.95 mL, 33.75 mmol) was slowly added, generating a great deal of HCl gas. The reaction mixture was stirred for 4 h at the same temperature. The solvent was removed under reduced pressure and the crude 6 was used without further purification. tert-butyl 2-iodobenzoate (7)5. To a dried flask flushed with argon, tert-butanol (1.9 g, 26 mmol) and anhydrous THF (20 mL) were added. The solution was cooled to –78 °C, 1.6 M n-BuLi in (16 mL, 26 mmol) was added, and the mixture was stirred for 1 h. At the same temperature, a solution of 2-iodobenzoyl chloride (6, 6.0 g, 22.5 mmol) in anhydrous THF (20 mL) was slowly added, and the mixture was slowly warmed to room temperature, then stirred for 12 h. The reaction was quenched by addition of 2 N HCl aq., then the mixture was neutralized with NaHCO3, and extracted with CH2Cl2. The organic layer was washed with brine and dried over Na2SO4. After removal of the solvent under reduced pressure, the residue was purified by column chromatography on silica gel (dichloromethane : petroleum ether = 1 : 4) to give pure 7 as a colorless oil (5.0 g, 73% yield). MS (ESI): m/z 304.8 [M+H]+ 305.0; 1H NMR (300 MHz, CDCl3) δ 1.63 (s, 9H), 7.07-7.80 (m, 4H); 13C NMR (75 MHz, CDCl3) δ 28.1, 82.6, 93.3, 127.8, 130.4, 131.9, 137.4, 140.9, 166.1. SiR. To a dried flask flushed with argon, tert-butyl 2-iodobenzoate (7, 1.50 g, 5 mmol) and anhydrous THF (10 mL) were added. The solution was cooled to –78 °C, 1.3 M sec-BuLi (3.8 mL, 5 mmol) was added, and the mixture was stirred for 1 h. At the
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same temperature, a solution of compound SiX (380 mg, 1 mmol) in anhydrous THF (10 mL) was slowly added, and the mixture was slowly warmed to room temperature, then stirred for 6 h. The reaction was quenched by addition of 2 N HCl aq., then the mixture was neutralized with NaHCO3, and extracted with CH2Cl2. The organic layer was washed with brine and dried over Na2SO4 and evaporated to dryness. This residue was dissolved in TFA (5 mL), and the mixture was stirred at r.t. overnight. After removal of the solvent under reduced pressure, the residue was dissolved in EtOAc. The organic layer was washed with saturated NaHCO3 aq., and brine and dried over Na2SO4. After removal of the solvent under reduced pressure, the residue was purified by column chromatography on silica gel (dichloromethane : ethyl acetate = 20 : 1) to give pure SiR as a light green solid (120 mg, 25% yield). MS (ESI): m/z 485.5 [M+H]+ 485.3, HRMS (ESI): m/z calcd for C30H36N2O2Si [M+H]+: 485.2619; found: 485.2623. 1H NMR (300 MHz, CDCl3): δ 0.62(s, 3H), 0.64 (s, 3H), 1.16 (t, 12H, J = 7.03 Hz), 3.37 (q, 8H, J = 6.98, 7.08 Hz), 6.50-8.00 ppm (m, 10H); 13C NMR (75 MHz, CDCl3): δ 1.6, 3.8, 15.9, 47.6, 95.7, 115.8, 119.3, 128.2, 128.9, 130.8, 131.8, 132.0, 134.2, 136.8, 140.6, 149.9, 157.6, 174.0 ppm. SiRH. To a solution of SiR (71 mg, 0.15 mmol) in EtOH (5 mL) was added 85% hydrazine hydrate (0.12 mL). The mixture was refluxed for 2h and diluted with CH2Cl2. The organic layer was washed with brine and dried over Na2SO4. After removal of the solvent under reduced pressure, the residue was purified by column chromatography on silica gel (dichloromethane : ethyl acetate = 10 : 1) to give pure SiRH as a colorless solid (55 mg, 73% yield). And the product was further recrystallized from dichloromethane/petroleum ether to give SiRH as colorless needle crystals. MS (ESI): m/z 499.3 [M+H]+ 499.3, HRMS (ESI): m/z calcd for C30H38N4OSi [M+H]+: 499.2888; found: 499.2886. 1H NMR (300 MHz, CDCl3): δ 0.53(s, 3H), 0.62 (s, 3H), 1.17 (t, 12H, J = 7.00 Hz), 3.37 (q, 8H, J = 7.00Hz), 4.47 (s), 6.40-8.30 ppm (m, 10H); 13C NMR (75 MHz, CDCl3): δ -1.3, 2.5, 13.7, 45.5, 68.8, 112.6, 117.7, 128.7, 129.3, 130.7, 131.7, 132.9, 135.5, 139.8, 147.3, 187.1 ppm. SiR-Cu. The salicylaldehyde (0.2 mmol, 25 mg) was added to a solution of SiRH (25 mg, 0.05 mmol) in MeOH (0.5 mL). The reaction mixture was reflux for 2h. After the solvent was evaporated under reduced pressure, the residue the was purified by column chromatography on silica gel (dichloromethane : ethyl acetate = 10 : 1) to give pure SiR-Cu as a colorless solid (24 mg, 79% yield). MS (ESI): m/z 603.4 [M+H]+ 603.3, HRMS (ESI): m/z calcd for C37H42N4O2Si [M+H]+: 603.3150; found: 603.3155. 1H NMR (300 MHz, CDCl3): δ 0.63 (s, 3H), 0.68 (s, 3H), 1.15 (t, 12H, J = 7.00 Hz), 3.33 (q, 8H, J = 6.94 Hz), 6.50-8.00 (m, 14H), 11.60 ppm (s, 1H); 13C NMR (75 MHz, CDCl3): δ 0.9, 2.1, 13.9, 45.3, 73.5, 116.0, 116.6, 118.4, 119.8, 123.8, 123.9, 125.5, 127.9, 128.6, 129.0, 129.6, 132.1, 132.3, 134.7, 135.5, 147.6, 150.2, 155.3, 159.7, 166.9 ppm. SiR-Hg. The SiRH (25 mg, 0.05 mmol) in DMF (0.5 mL) was added to a solution of phenyl isothiocyanate (0.05 mL, 0.33 mmol) in DMF (0.5 mL). The reaction mixture
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was stirred for 12 h at room temperature. After the solvent was evaporated under reduced pressure, the residue the was purified by column chromatography on silica gel (dichloromethane : ethyl acetate = 10 : 1) to give pure SiR-Hg as a light blue solid (20 mg, 63% yield). And the product was further recrystallized from dichloromethane/petroleum ether to give SiR-Hg as light blue crystals. MS (ESI): m/z 634.2 [M+H]+ 634.3, HRMS (ESI): m/z calcd for C37H43N5OSSi [M+H]+: 634.3030; found: 634.3030. 1H NMR (300 MHz, CDCl3): δ 0.55 (s, 3H), 0.60 (s, 3H), 1.16 (t, 12H, J = 6.98 Hz), 3.36 (q, 8H, J = 6.86 Hz), 6.50-8.00 ppm (m, 17H); 13C NMR (75 MHz, CDCl3): δ 1.2, 1.9, 14.4, 46.0, 75.6, 115.8, 116.9, 125.6, 126.7, 127.6, 130.0, 130.3, 130.6, 131.0, 131.3, 136.0, 139.6, 134.0, 148.4, 153.2, 154.9, 169.2, 184.1 ppm. 1. S.-K. Ko, Y.-K. Yang, J. Tae, I. Shin, J. Am. Chem. Soc. 2006, 128, 14150-14155. 2. G. M. Sheldrick, Acta Crystallogr., Sect. A 2008, 64, 112-122. 3. T. Saitoh, S. Yoshida, J. Ichikawa, J. Org. Chem. 2006, 71, 6415-6419. 4. T. Egawa, Y. Koide, K. Hanaoka, T. Komatsu, T. Terai, T. Nagano, Chem. Commun.
2011, 47, 4162-4164. 5. V. V. Zhdankin, D. N. Litvinov, A. Y. Koposov, T. Luu, M. J. Ferguson, R.
McDonald, R. R. Tykwinski, Chem. Commun. 2004, 106-107.
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1H-NMR, 13C-NMR and HRMS spectra of Si-rhodamines
1H-NMR spectrum of SiR
13C-NMR spectrum of SiR
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HRMS spectrum of SiR
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1H-NMR spectrum of SiRH
13C-NMR spectrum of SiRH
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HRMS spectrum of SiRH
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1H-NMR spectrum of SiR-Cu
13C-NMR spectrum of SiR-Cu
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HRMS spectrum of SiR-Cu
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1H-NMR spectrum of SiR-Hg
13C-NMR spectrum of SiR-Hg
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HRMS spectrum of SiR-Hg
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Fig. S1 Single-crystal structure of SiR-Hg. Hydrogen atoms and a solvent molecule
CH2Cl2 are omitted for clarity.
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Fig. S2 A reversible blue color change of SiR solution (20 uM, MeCN) after adding
AcOH or Et3N.
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Fig. S3 Photostability of SiR (5 µM) in HEPES buffer solution at pH 7.4. The sample
was continuously irradiated by a xenon lamp (150 W) at 10 nm slit width at 650 nm.
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(a) (b) (c)
Fig. S4 Cells incubated with SiR (50 uM). The SH-SY5Y cells were treated with SiR
for 10 min, washed with PBS to remove the remaining SiR. (a) Microscopic image of
SH-SY5Y cells. (b) Microscopic image of SH-SY5Y cells treated with 50 uM SiR. (c)
Fluorescence microscopic image of SH-SY5Y cells treated with SiR. Scale bar = 50
um.
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Fig. S5 pH-dependence of the fluorescence intensity of SiR (5 uM) in buffer solution
(MeCN/H2O = 1/1, 20 mM HEPES).
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Fig. S6 The color changes of compounds RH and SiRH on a thin-layer plate. RH left
a pink color band or spot on silica gel column or thin-layer owing to the ring-opening
of corresponding spirolactam caused by acid hydroxyl on silica gel. However, no
color or a light yellow color change was observed for SiRH.
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Fig. S7 pH-dependence of the fluorescence intensity of RH (red cycle) and SiRH
(black triangle). The fluorescence intensity of RH increased at pH range from pH 6 to
4, indicating the formation of ring-opened structure. Unlike RH, SiRH gave
negligible responses to the proton at that pH range.
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Fig. S8 UV-vis spectral changes of SiRH (20 uM) observed upon addition of Cu2+ in
HEPES buffer solution at pH 7.4. The absorption of SiRH was not recorded owning
to the limited solubility. Inset: Color changes of SiRH upon addition of 10 equiv of
Cu2+.
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Fig. S9 Emission spectra changes of SiRH (5 uM) upon addition of 10 equiv of Cu2+
in HEPES buffer solution at pH 7.4. The black line represents the fluorescence
emission of SiRH excited at 620 nm. The red and blue lines represent the
fluorescence emission of SiRH with Cu2+ excited at 420 and 620 nm, respectively.
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Fig. S10 ESI mass spectra (positive) of SiRH (20 µM) in the presence of Cu2+ (10
equiv). Inset: The possible chelating complex formed from SiRH interacting with
Cu2+.
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Fig. S11 Job’s plot for SiRH with Cu2+, indicating 2:1 binding stoichimetry. [SiRH] +
[Cu2+] = 20 uM.
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Fig. S12 Proposed binding mode for SiRH with Cu2+.
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Fig. S13 Color changes of SiRH (20 uM) upon addition of 10 equiv of various metal
ions in the HEPES buffer solution at pH 7.4. From left to right: Ag+, Mg2+, Zn2+, Ca2+,
Ba2+, Co2+, Ni2+, Fe2+, Cd2+, Pb2+, Hg2+, Fe3+, Cr3+ and Cu2+.
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Fig. S14 UV-vis spectral changes of SiR-Cu (20 uM) observed upon addition of 10
equiv of Cu2+ in HEPES buffer solution at pH 7.4. The absorption of SiR-Cu was not
recorded owning to the limited solubility. Inset: Color changes of SiR-Cu upon
addition of 10 equiv of Cu2+.
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Fig. S15 Emission spectra changes of SiR-Cu (5 uM) upon addition of 10 equiv of
Cu2+ in HEPES buffer solution at pH 7.4. The black line represents the fluorescence
emission of SiR-Cu excited at 620 nm. The green and red lines represent the
fluorescence emission of SiR-Cu with Cu2+excited at 420 and 620 nm, respectively.
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Fig. S16 UV-vis spectral changes of SiR-Hg (5 uM) observed upon addition of 1.0
equiv of Hg2+ in HEPES buffer solution at pH 7.4. Inset: color change of SiR-Hg
upon addition of 1.0 equiv of Hg2+.
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Fig. S17 Time course of the fluorescence response of SiR-Hg (5 µM) in the presence
of Hg2+ (5 µM) in HEPES buffer solution at pH 7.4. After adding Hg2+, a remarkable
fluorescence increase was obtained instantly up to 3 min, and leveled off thereafter,
indicating a fast response and sufficient stability of SiR-Hg.
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Fig. S18 Hg2+-induced ring-opening of SiR-Hg, forming the highly fluorescent
product.
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Fig. S19 ESI mass spectra (positive) of SiR-Hg (20 µM) in the presence of Hg2+ (1.2
equiv). Inset: The corresponding product formed from SiR-Hg reacted with Hg2+.
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Fig. S20 The fluorescence intensity (680 nm) of SiR-Hg upon addition Hg2+. The
regression equation was F/F0 = 13.02 + 99.60 × [Hg2+] (µM) with a linear coefficient
of 0.996. The detection limit (3σ) was 5 nM.
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Table S1 Crystal data and structure refinement for a20109c.
Identification code a20109c
Empirical formula C37.50H44ClN5OSSi
Formula weight 676.38
Temperature 153(2) K
Wavelength 0.71073 Å
Crystal system, space group Orthorhombic, Pccn
Unit cell dimensions a = 30.130(6) Å α = 90°
b = 13.543(3) Å β = 90°
c = 19.002(4) Å γ = 90°
Volume 7754(3) Å3
Z, Calculated density 8, 1.159 Mg/m3
Absorption coefficient 0.218 mm−1
F(000) 2872
Crystal size 0.25 x 0.25 x 0.10 mm
Theta range for data collection 1.35 to 25.02 °
Limiting indices -33<=h<=35, -16<=k<=8, -22<=l<=22
Reflections collected / unique 29442 / 6850 [R(int) = 0.0605]
Completeness to θ = 25.02 99.9 %
Absorption correction none
Max. and min. transmission 0.9786 and 0.9476
Refinement method Full-matrix least-squares on F2
Data / restraints / parameters 6850 / 7 / 456
Goodness-of-fit on F2 1.049
Final R indices [I>2sigma(I)] R1 = 0.0851, wR2 = 0.2260
R indices (all data) R1 = 0.1164, wR2 = 0.2543
Largest diff. peak and hole 0.561 and -0.308 e. Å−3
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