Sonic vcx 750

Graphene was prepared following the process developed in our previous work [39 (link)]. Briefly, 4 g of graphite powder (Sigma-Aldrich Korea Ltd., Yongin, Korea, 20 µm) was dispersed in 200 mL of an aqueous mixture containing 20 vol % acetone and 68 vol % tetrahydrofuran. The dispersion was then ultrasonically treated for 1 h using a horn probe sonic tip (Sonic VCX 750, Sonics & Materials, Inc., Newtown, CT, USA). A cooling water system was used to keep the processing temperature below 5 °C throughout. The ultrasonic power was set to 600 W with a pulse for 20 s on and 10 s off. After the ultrasonic treatment, the black dispersion was centrifuged at 1500 rpm for 30 min. The supernatant was then carefully decanted and retained for the next process. The concentration of the graphene was estimated to be around 250 µg/mL.

All synthetic procedures were performed in air. Reagents and solvents were obtained from commercial sources. The organic reactants for the cycloaddition reaction (alkynes and benzyl azide) were further purified prior to use by distillation. DAPTA was synthesized using the published procedure [8 (link),10 (link)]. The ultrasound irradiation was accomplished with a high-intensity ultrasonic probe SONIC VCX 750 (Sonics & Materials Inc., Newtown, CT, USA) model (20 kHz, 750 W) using a titanium horn. Elemental analyses (C, H, and N) were carried out by the Microanalytical service of Instituto Superior Tecnico. ¹H and ³¹P NMR spectra were obtained using a Bruker Advance (Bruker, Billerica, MA, USA) 400 and 500 MHz spectrometers at ambient temperature. Chemical shifts δ are quoted in ppm. ¹H chemical shifts were internally referenced to residual protio-solvent resonance and are reported relative to SiMe₄. ³¹P chemical shifts were referenced to external 85% phosphoric acid. Assignments of ¹H signals rely on COSY experiments. Electrospray mass (ESI-MS) spectra were obtained on a Varian 500-MS LC Ion Trap Mass Spectrometer (Agilent Technologies, Santa Clara, CA, USA) equipped with an electrospray ion source. All compounds were observed in the positive mode (capillary voltage = 80–105 V).