Abstract
Carbon dots (C-dots) represent a new class of carbon-based materials that were discovered recently and have drawn the interest of the scientific community, particularly because of their attractive optical properties and their potential as fluorescent sensors. Investigation of the chemical structure of C-dots is extremely important for correlating the surface modifier composition with C-dot optical properties and allow for structure–properties fine tuning. In this article, we report the structural analysis of the surface modifiers of three different types of C-dot nanoparticles (Cwax, Cws, and Csalt) by use of 1D- and 2D-high-resolution NMR spectroscopy in solution. We unambiguously verify that the structure of the modifier chains remains chemically unchanged during the passivation procedure, and confirm the covalent attachment of the modifiers to the nanoparticle core, which contributes no signal to the solution-state NMR spectra. To our knowledge, this is the first study confirming the full structural assignment of C-dot organic surface modifiers by use of solution NMR spectroscopy.
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References
Baker SN, Baker GA (2010) Luminescent carbon nanodots: emergent nanolights. Angew Chem Int Ed 49:6726–6744
Bourlinos AB, Stassinopoulos A, Anglos D, Zboril R, Karakassides M, Giannelis EP (2008a) Surface functionalized carbogenic quantum dots. Small 4:455–458
Bourlinos AB, Stassinopoulos A, Anglos D, Zboril R, Georgakilas V, Giannelis EP (2008b) Photoluminescent carbogenic dots. Chem Mater 20:4539–4541
Braun S, Kalinowski HO (1998) 150 and more basic NMR experiments: a practical course, 2nd edn. Wiley, Weinheim
Cao L, Wang X, Meziani MJ, Lu FS, Wang HF, Luo PJG, Lin Y, Harruff BA, Veca LM, Murray D, Xie SY, Sun YP (2007) Carbon dots for multiphoton bioimaging. J Am Chem Soc 129:11318–11319
Dais P, Spyros A (1995) 13C relaxation and local chain dynamics of synthetic polymers in solution and in the bulk. Progr NMR Spectrosc 27:555–633
Diaz D, Rivera M, Ni T, Rodriguez JC, Castillo-Blum SE, Nagesha DK, Robles J, Alvarez-Fregoso OJ, Kotov NA (1999) Conformation of ethylhexanoate stabilizer on the surface of CdS nanoparticles. J Phys Chem B 103:9854–9858
Du F, Zhou H, Chen L, Zhang B, Yan B (2009) Structure elucidation of nanoparticle-bound organic molecules by 1H NMR. Trends Anal Chem 28:88–95
Holland GP, Sharma R, Agola JO, Amin S, Solomon VC, Singh P, Buttry DA, Yarger JL (2007) NMR characterization of phosphonic acid capped SnO2 nanoparticles. Chem Mater 19:2519–2526
Kitaygorodskiy A, Wang W, Xie SY, Lin Y, Shiral Fernando KA, Wang X, Qu L, Chen B, Sun YP (2005) NMR detection of single-walled carbon nanotubes in solution. J Am Chem Soc 127:7517–7520
Liu H, Ye T, Mao C (2007) Fluorescent carbon nanoparticles derived from candle soot. Angew Chem 119:6593–6595
Spyros A, Dais P, Marchessault RH (1995) Local chain motions of poly(P-hydroxyoctanoate) in the bulk. 13C NMR relaxation study. J Polym Sci B 33:367–378
Suda Y, Ono T, Akazawa M, Sakai Y, Tsujino J, Homma N (2002) Preparation of carbon nanoparticles by plasma-assisted pulsed laser deposition method—size and binding energy dependence on ambient gas pressure and plasma condition. Thin Solid Films 415:15–20
Sun YP, Zhou B, Lin Y, Wang W, Shiral-Fernando KA, Pathak P, Meziani MJ, Harruff BA, Wang X, Wang H, Luo PG, Yang H, Kose ME, Chen B, Veca LM, Xie SY (2006) Quantum-sized carbon dots for bright and colorful photoluminescence. J Am Chem Soc 128:7756–7757
Tian L, Ghosh D, Chen W, Pradhan S, Chang X, Chen S (2009) Nanosized carbon particles from natural gas soot. Chem Mater 21:2803–2809
Tomaselli M, Yarger JL, Bruchez M, Havlin RH, deGraw D, Pines A, Alivisatos AP (1999) NMR study of InP quantum dots: surface structure and size effects. J Chem Phys 110:8861–8864
Wang X, Cao L, Yang ST, Lu F, Meziani MJ, Tian L, Sun KW, Bloodgood MA, Sun YP (2010) Bandgap-like strong fluorescence in functionalized carbon nanoparticles. Angew Chem 122:5438–5442
Willis AL, Turro NJ, O’Brien S (2005) Spectroscopic characterization of the surface of iron oxide nanocrystals. Chem Mater 17:5970–5975
Zhang B, Yan B (2010) Analytical strategies for characterizing the surface chemistry of nanoparticles. Anal Bioanal Chem 396:973–982
Zhou H, Du F, Li X, Zhang B, Li W, Yan B (2008) Characterization of organic molecules attached to gold nanoparticle surface using high resolution magic angle spinning 1H NMR. J Phys Chem C 112:19360–19366
Acknowledgments
This research was supported in part by the University of Crete (Project KA-3047) and the Operational Program Research and Development for Innovations-European Regional Development Fund (project CZ.1.05/2.1.00/03.0058) and Operational Program Education for Competitiveness (CZ.1.07/2.3.00/20.0017).
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Philippidis, A., Spyros, A., Anglos, D. et al. Carbon-dot organic surface modifier analysis by solution-state NMR spectroscopy. J Nanopart Res 15, 1777 (2013). https://doi.org/10.1007/s11051-013-1777-0
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DOI: https://doi.org/10.1007/s11051-013-1777-0