Synthesis of functionalized, dispersible carbon coated cobalt nanoparticles for potential biomedical applications Quirin M. Kainz, a Soraia Fernandez, a Corina Eichenseer, a Francesca Besostri, a Helmut Körner, b Rainer Müller, c Oliver Reiser a, * a Universität Regensburg, Institut für Organische Chemie, Universitätsstr. 31, 93053 Regensburg, Germany. Fax: 49 941 9434121; Tel: 49 941 9434631; E-mail: oliver.reiser@chemie.uni-regensburg.de b Institut für Physik c Institut für Physikalische Chemie Supporting Information All reactions were carried out in oven-dried glassware under an atmosphere of dry nitrogen unless stated otherwise. All commercially available reagents were used as received. Carbon coated cobalt nanoparticles were purchased from Turbobeads Llc (Co/C, 20.5 m 2 /g, mean particle size ≈25 nm). Prior to use, they were washed in a concentrated HCl (Merck, puriss)/deionized water (Millipore) mixture (1:1) 5 times for 24 h. Acid residuals were removed by washing with Millipore water (5x) and the particles were dried at 50 _C in a vacuum oven. Carbon coated cobalt nanoparticles were purchased from Turbobeads Llc (Co/C, 20.5 m 2 /g, mean particle size ≈25 nm). Prior to use, they were washed in a concentrated HCl (Merck, puriss)/deionized water (Millipore) mixture (1:1) 5 times for 24 h. Acid residuals were removed by washing with Millipore water (5x) and the particles were dried at 50 °C in a vacuum oven. Pent-4-ynoic acid andhydride, 1 azide functionalized Co/C nanoparticles (loading: 0.14 mmol/g), 2 propargyl-[G3]-(OH) 8 2, 3 propargyl-[G3]-(NH 3 + TFA_) 8 3, 4 Co/C-[G3]- (OH) 8 4, 5 Co/C-[G3]-(NH3 + TFA_) 8 5, 5 2-azidoethyl-β-D-gluco-pyranoside, 6 pyrene-[G3]-(OH) 8 7a, 7 pyrene-[G3]- (alkyne) 8 7b, 7 phenylethylamine functionalized carbon coated cobalt nanoparticles 21, 8 aziridine (22) 9 were prepared according to literature procedures. Magnetic nanobeads were dispersed using an ultrasound bath (Sonorex RK 255 H-R, Bandelin) and recovered with the aid of a neodymium based magnet (N48, W-12-N, Webcraft GmbH, side length 12 mm) unless indicated otherwise. Microwave reactions were carried out using a CEM Discover S-Class microwave reactor and appropriate glass tubes. ATR-IR spectroscopy was carried out on a Biorad Excalibur FTS 3000 spectrometer, equipped with a Specac Golden Gate Diamond Single Reflection ATR-System. Diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) was performed on an JASCO FT/IR-610 spectrometer using a PIKE Reflectance Analysis Kit. Thermogravimetric analysis was performed using a Perkin Elmer TGA7 apparatus. For TEM measurements, sample suspension drops were placed on a cupper grid (400 mesh) and subsequently blotted dry with a filter paper. The samples were examined in a LEO912AB electron microscope (Zeiss, Oberkochen/Germany) operating at 100 kV, equipped with a side-mounted CCD-camera capable of recording images with 1k x1k pixels. High-resolution transmission electron microscopy was carried out using a Philips CM30 ST equipped with a LaB6 cathode and operated at 300kV point resolution (~ 4 Å) at the ETH Zürich. Pyrene-[G3]-(NH 3 + TFA – ) 8 7c: 248 mg (0.20 mmol) of pyrene tagged dendrimer 7a, 86 mg (0.74 mmol) DMAP and 48 µL absolute pyridine were dissolved in 5 mL of dry CH 2 Cl 2 . A solution of 1.44 g (4.00 mmol) 3-((tert- butoxycarbonyl)amino)-propanoic anhydride in 8 mL of dry CH 2 Cl 2 was added dropwise and the resulting mixture was stirred for 24 h at room temperature. Water (10 mL) was added and the mixture stirred for further 3 hours. After dilution with 50 mL of CH 2 Cl 2 the organic layer was successively washed with 10% HCl (3 x 20 mL), 10% Na 2 CO 3 (3 x 20 mL) and brine (20 mL). The organic phase was dried over MgSO4, filtered and concentrated under reduced pressure. Purification by column chromatography eluting with PE:EE 8:2 and gradually increasing polarity to 100% ethyl acetate yielded 435 mg (0.17 mmol, 85%) of pyrene-[G3]-(NHBoc 3 ) 8 as a yellow waxy solid. 1 H-NMR (400 MHz, CDCl3): δ = 8.20 (d, J=9.3, 1H), 8.06 (dd, J=7.6, 2.2, 2H), 8.03-7.98 (m, 2H), 7.93-7.87 (m, 3H), 7.77 (d, J=7.8, 1H), 7.74 (s, 1H), 6.53-6.40 (bs, 1H),5.44-5.06 (m, 10H), 4.31 (t, J=6.7, 2H), 4.22-4.06 (m, 28H), 3.28 (d, J=5.4, 16H), 3.17 (dd, J=12.3, 6.2, 2H), 2.45 (t, J=6.0, 16H), 2.23 (t, J=7.1, 2H), 2.12 (dt, J=14.3,7.2, 2H), 2.05-1.96 (m, 2H), 1.34 (s, 72H), 1.19 (s, 3H), 1.14 (s, 12H), 1.12 (s, 6H). 13 C-NMR (100.6 MHz, CDCl3) δ = 173.3, 172.0, 171.7, 171.4, 155.8, 141.8, 135.8, 131.3, 130.8, 129.9, 128.7, 127.4, 127.3, 127.3, 126.7, 125.8, 125.0, 124.9, 124.9, 124.8, 124.7, 124.6, 123.3, 79.2, 77.4, 66.1, 65.2, 64.9, 58.4, 47.8, 46.6(0), 46.5(5), 46.4, 36.3, 36.1, 35.8, 34.4, 32.8, 30.3, 28.5, 28.3, 28.1, 27.4, 17.7, 17.5, 17.4; m.p. 48 °C; IR (v/cm -1 ): 3374, 2977, 1737, 1696, 1513, 1366, 1245, 1160, 1127, 966, 848, 757; MS (ESI): m/z = 2610.8 (MH + ). Electronic Supplementary Material (ESI) for Faraday Discussions. This journal is © The Royal Society of Chemistry 2014