Nanostructure Origins of C₆₀ Fluorescence in Pyridine

Abstract

The nanostructure origins of three distinct and strong fluorescence bands of C60 in room-temperature pyridine are reported for the first time. Fluorescence study and in-situ TEM observation on C60-pyridine solutions with different setting times exhibit that the blue fluorescence peaks centered at 440 nm originate from C60 nanoparticles; the yellow-green fluorescence band located at 575 nm derives from C60 lace-like cluster; and the salmon pink fluorescence band around 700 nm arises from C60 microbulk in solution. The conclusions are supported further by investigation on the C60-toluene system as well.

Real‐Time Translocation of Fullerene Reveals Cell Contraction

“…Centrifugation at 7500 rpm for 3 min markedly reduced the narrow peak at 719 nm, but did not significantly alter the broad fluorescence peak at 540 nm, suggesting that the fluorescence at 719 nm was emitted by less dissolved C 70 . This result is reminiscent of that observed for C 60 ‐pyridine suspensions, where fluorescence peaks at 440, 575, and 700 nm were assigned to C 60 nanoparticles, C 60 lace‐like clusters, and C 60 microbulks, respectively 10. However, the fluorescence bands of C 60 in GA were weaker and less distinctive than those observed for C 70 , possibly because of the greater symmetry and broader fluorescence emission of C 60 , which extends into the near‐infrared region 11, 12…”

“…In addition, prior to the filtrations, “lace‐like” clusters were observed. The sizes of these clusters ranged from tens of nanometers up to micrometers, similar to that observed for pyridine‐solubilized C 60 10. A separate NMR study found no spectral signatures for C 70 –GA, indicating their binding to be of a noncovalent nature.…”

Liquid‐Phase Exfoliation of Graphite Towards Solubilized Graphenes

“…The pyridine case suggests that aromatic donors may also exfoliate graphite in the reverse way, that is, charge transfer through π – π stacking from the solvent molecules to the carbon layers (graphite may act either as donor or acceptor, depending on the case). Similar donor–acceptor interactions are quite common in several graphite‐intercalated compounds18–20 as well as in the pyridine–C 60 system24 and in carbon nanotubes solubilized by certain aromatic amines 25. Likewise, molten 2‐cyanopyridine (mp: 26–28 °C) and benzylamine also provided colloidal dispersions with graphite but aromatic donors like methylpyridines (picolines), aminopicolines, aniline, N , N ‐dimethylaniline, pyrrole, and thiophene did not.…”

Solvent-induced optical properties of C60

“…In view of the C 60 lace-like cluster which seems similar to that created in pyridine [13], we suppose, besides the contribution of solvent polarity [22,23], its generation would be more related to the electron-pair donation ability of acetonitrile, with which little charge transfer would occur between acetonitrile and C 60 . To exactly confirm this strong interaction, cyclic voltammograms of C 60 in acetonitrile were recorded at room temperature.…”

“…In contrast, a series of strong fluorescence bands of C 60 , centered at 440, 575 and 700 nm, respectively, were achieved from C 60 -pyridine solution by some of us [12]. Especially, different C 60 aggregates produced in pyridine have been assumed to be related with the three distinctive fluorescence bands in our latest work [13]. This is of great interest for a variety of reasons, for example, the nature interaction between C 60 and solvent, the inevitable correlation of C 60 nano-aggregates with fluorescence emissions.…”