Supporting Information

Transcription

1 Supporting Information Phenyl-Modified Carbon Nitride Quantum Dots with Distinct Photoluminescence Behavior Qianling Cui, Jingsan Xu,* Xiaoyu Wang, Lidong Li,* Markus Antonietti, and Menny Shalom anie_ _sm_miscellaneous_information.pdf

2 Experimental Section Preparation of bulk Ph-CN and colloidal Ph-CN nanoparticles All the chemicals were purchased from Sigma-Aldrich and used without further purification. Typically, 1.30 g of cyanuric acid (C) 1.80 g of 2,4-diamino-6-phenyl-1,3,5-triazine (Mp) were weighed and mixed in 50 ml deionized water. The mixture was shaken overnight to form a milky CMp complex. Afterwards, the CMp powder was washed with water and separated by centrifugation at 5000 rpm. After drying at 60 o C in vacuum, the CMp precursor was transferred into a crucible, capped and placed in an oven at 450 o C for 2 h under the protection of nitrogen atmosphere, with a heating rate of 2.3 o C/min. After cooling to room temperature the yellow carbon nitride powders were collected for further processing and measurements. The CN colloidal suspensions were obtained by sonication of the as-prepared bulk CN in water. In detail, 30 mg of bulk CN powder were dispersed in 30 ml of water, and then sonicated for about 4 hours. The initial formed suspension was then centrifuged at 5000 rpm for 30 min to remove the residual large particles before further measurements. Determination of Absolute Quantum Yields The absolute quantum yields of the CN colloidal dispersions were determined using a spectrofluorometer (FLSP920, Edinburgh Instruments LTD) equipped with an integrating sphere. The integrating sphere consists of a 120 mm inside diameter spherical cavity, which is machined from BENFLEC block. 3 ml of aqueous dispersion of sample was sealed in a quartz cell (10 mm 10 mm), and its maximal absorption intensity was controlled in the range of The same volume of water was used as the blank sample. The excitation wavelength was set at 340 nm. The scattering spectral range of blank and sample was set from 320 nm to 360 nm, and the emission spectral range was from 400 to 650 nm. Cytotoxicity Assay by MTT Method

3 The cytotoxicity of the NPs was studied using a 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) cell-viability assay. HeLa cervical carcinoma cells were grown in Dulbecco s modified Eagle s medium (DMEM) containing 10% (v/v) fetal bovine serum (FBS). Then, the cells were seeded into 96-well plates at a density of cells in each well. After 24 h of incubation at 37 C in a 5% CO 2 humidified atmosphere, the cells were treated with different amounts of CN colloidal dispersions (10 µl, 20 µl, 40 µl, 60 µl, 80 µl, 100 µl, 120µL), and cultured for another 24 h. After pouring out the medium, 100 µl of freshly prepared MTT (1 mg ml -1 in PBS) was added to each well and incubated for 4 hours. After removing the MTT medium solution, the cells were lysed by adding 100 µl of DMSO. The plate was gently shaken for 5 minutes, and then the absorbance of purple formazan at 570 nm was monitored using a Spectra MAX 340PC plate reader. Cellular Imaging Experiments 100 μl of CN colloidal dispersion was added into 1 ml of DMEM medium containing HeLa cells in a mm plate. The plate was then incubated for 10 hours at 37 C in a humidified environment containing 5% CO 2. Then, fluorescence images and phase contrast bright-field images were recorded on a confocal fluorescence microscope (Olympus FV1000- IX81). For observing the signals of CN nanoparticles, excitation wavelength was set at 405 nm and fluorescence signals were collected from 450 nm to 550 nm. Characterization The size distributions and zeta-potential measurements of the colloidal suspensions were measured by dynamic light scattering with a Malvern Zetasizer Nano ZS90. The morphology of the nanoparticles was characterized by transmission electron microscopy (TEM, Hitachi H- 7650) and atomic force microscopy (AFM, Bruker Multimode 8). The X-ray diffraction (XRD) patterns were recorded on a Bruker D8 Advance X-ray diffractometer using Cu-K α radiation. FT-IR spectra were got on a Nicolet is5 FT-IR spectrometer. 13 C solid-state nuclear magnetic resonance (NMR) spectra were determined on a Bruker Advance 100 MHz

4 spectrometer. UV-vis absorption spectra of aqueous dispersions were measured on a Hitachi U3900 spectrophotometer. Solid UV-vis absorbance spectra were measured using a Cary 500 Scan spectrophotometer equipped with an integrating sphere. Photoluminescence spectra of the samples were obtained by a Hitachi F-7000 spectrometer. Fluorescence images of CN colloids were recorded using an Olympus FV1000-IX81 confocal laser scanning microscope through a 100 objective, with nm excitation produced by a 100 W mercury lamp light source.

5 Intensity (a.u.) Figure S1. Illustration of the preparation of phenyl modified CN colloidal aqueous suspension Theta (degree) Figure S2. XRD patterns of the CN samples. From top to bottom: CN bulk, CN nanoparticles obtained after 4 h sonication, and CN nanoparticles obtained after 24 h sonication.

6 PL intensity (a.u.) Figure S3. Solid state 13 C NMR spectra of Ph-CN and Ph-CNB. (a) (b) Ph-CN Ph-CNB Wavelength (nm) Figure S4. (a) Solid UV-vis absorption spectra and (b) PL spectra of bulk Ph-CN and Ph- CNB.

7 Figure S5. (a) UV-vis absorption spectra and (b) PL spectra (340 nm excitation) of CN nanoparticle suspension made from melamine-cyanuric acid supramolecules. Ph-CN CM-CN Figure S6. Photograph: THF suspensions of Ph-CN and CM-CN (carbon nitride made from cyanuric acid-melamine complex) after standing for about 4 hours.

8 Figure S7. Normalized PL spectra of (a) Ph-CN and (b) Ph-CNB colloids dispersion obtained by sonication in different solvents.

9 Normalized PL (a.u.) Normalized PL (a.u.) Intensity (a.u.) Intensity (a.u.) (a) Ph-CN (b) 2000 Ph-CNB Wavelength (nm) Wavelength (nm) (c) 1.0 (d) Ph-CN 0.2 Ph-CNB ph Value ph Value Figure S8. PL spectra of (a) Ph-CN and (b) Ph-CNB nanoparticles in water with ph ranging 0~14 under 340 nm wavelength excitation; (c) and (d) corresponding normalized PL intensity depending on ph value.