Semiconductor Nanocrystals with Different Size and. Shape

Transcription

1 Supporting Information Determination of Concentration of Amphiphilic Polymer on the Surface of Encapsulated Semiconductor Nanocrystals with Different Size and Shape Aleksandra Fedosyuk, Aliaksandra Radchanka, Artsiom Antanovich, Anatol Prudnikau, Maksim V. Kvach, Vadim Shmanai, and Mikhail Artemyev* Institute for Physical Chemical Problems, Belarusian State University, Leningradskaya str. 14, Minsk , Belarus Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus, Minsk , Belarus * m_artemyev@yahoo.com 1. Synthesis of 4-(fluorescein-6-carboxamido)-butylammonium chloride (3). S1

2 Scheme S1. Reagents and conditions: i, N-Fmoc-1,4-butanediamine hydrobromide, Et 3 N, CH 2 Cl 2, DMF, 1h; ii, piperidine, DMF, 3h, column chromatography; iii, HCl, MeOH. 2,3,4,5,6-Pentafluorophenyl 3',6'-bis(cyclohexanecarbonyloxy)-3- oxospiro[2-benzofuran-1,9'-xanthene]-6-carboxylate 1 (0.5 mmol, 381 mg) was dissolved in dichloromethane (50 ml) and N-Fmoc-1,4-butanediamine hydrobromide (0.5 mmol, 196 mg) followed by triethylamine (0.6 mmol, 83 µl) and DMF (50 ml) were added. Reaction mixture was stirred at room temperature for 1 h, diluted with dichloromethane (200 ml), washed with water (5 200 ml), dried over Na 2 SO 4 and evaporated in vacuo. Resulted derivative 2 was dissolved in mixture of piperidine (45 mmol, 4.44 ml) and DMF (15 ml) and stirred at room temperature for 3h. Volatile products were removed in vacuo, the residue was purified by column chromatography on silica eluting with a step gradient (0 60% v) of MeOH in a triethylamine-dichloromethane mixture 1:9 (v/v). Fractions containing desired product in the form of triethylammonium salt were collected and rotary evaporated. The residue was dissolved in MeOH (5 ml) and solution of HCl in MeOH (prepared by carefully dissolving 100 µl SOCl 2 in 5 ml MeOH) was added until precipitate formed was redissolved. Desired product 3 was precipitated by addition of Et 2 O, filtered off and dried in vacuo. The yield of 3 is 170 mg (70%). 1 H NMR (d 4 -MeOD) δ = 8.38 (d, 1H, J = 8.3 Hz), 8.27 (dd, 1H, J = 8.3 Hz, 4 J = 1.6 Hz), 7.85 (s, 1H), 7.28 (d, 2H, J = 8.7 Hz), 7.21 (s, 2H), 7.05 (d, 2H, J = 8.7 Hz), 3.43 (t, 2H, J = 6.4 Hz), 2.96 (t, 2H, J = 7.1 Hz), (m, 2H). 13 C NMR (d 4 -MeOD) δ = (br s), , , (br s), , , , (br s), , (br s), (br s), (br s), , 40.35, 40.30, 27.31, Control gel-electrophoresis of NCs encapsulated with PMAT-dye purified out of free PMAT-dye. S2

3 Figure S2. Gel-electrophoresis of CdSe/ZnS QDs #4 encapsulated with PMAT-dye before gel-filtration through Sephacryl S-500 (line 3), after gel-filtration (retention time is between min, line 2) and free PMAT-dye (line 1, 2% agarose gel in 0.05 M carbonate-bicarbonate buffer (ph=9.5), V=50 V, t=15 min). It can be seen that track 3 has clearly visible green emission footprint of free PMAT-dye, while after gel-filtration (track 2) the PMAT-dye emission is absent. 3. Determination of molar absorption coefficients for ZnSe quantum dots in chloroform. ZnSe core-shell QDs with the diameter from ca. 1.8 to 6 nm were synthesized by high temperature synthesis according to published procedure 1. ZnSe QDs were deposited with methanol and redispersed in fresh chloroform in order purify the colloidal solution out of zinc salts. An aliquot of solution with registered optical absorption spectrum was dried in a tube and treated with concentrated nitric acid at 60 º C on water bath for 5 hours. The resultant solution of zinc nitrate was diluted with bi-distilled water and the concentration of zinc determined with ICP-AES analyzer (Varian Liberty Sequential) against analytical standard. The molar extinction coefficient of ZnSe QDs versus their average diameter was determined from the concentration of Zn and the optical density at first exciton of ZnSe QDs by standard procedure 2. Fig. S1 represents the experimental molar absorption coefficient for ZnSe QDs of different diameter in chloroform. S3

4 Figure S3. Molar absorption coefficient ε for ZnSe QDs of different diameter in chloroform. 4. Optical absorption spectrum of PMAT-dye S4

5 Figure S4. Optical absorption spectrum of PMAT-dye before encapsulation in a buffer solution at ph Transmission electron microscopy S5

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8 Figure S5. TEM images and size histograms of nanocrystals of different type and structure: QDs1 (a), QDs2 (b), QDs3 (c), QDs4 (d), QDs5 (e), QDs6 (f), QDs7 (g), NRs1 (h). The samples names correspond to notations in the Table 1 of the main text. REFERENCES (1) Norris, D. J.; Yao, N.; Charnock, F. T.; Kennedy, T. A. High-Quality Manganese-Doped ZnSe Nanocrystals. Nano Lett. 2001, 1, 3 7. (2) Yu, W. W.; Qu, L.; Guo, W.; Peng, X. Experimental Determination of the Extinction Coefficient of CdTe, CdSe, and CdS Nanocrystals. Chem. Mater. 2003, 15, S8