Solvent Engineering for Shape-Shifter Pure Fullerene (C₆₀)

Abstract

As a highly anticipated technique for bottom-up nanotechnology, i.e., shape control of pure functional molecules, we here report controlled formation of two-dimensional (2D) objects such as hexagons and rhombi and their selective shape shifting into one-dimensional (1D) rods through solvent-dependent changes of crystal lattice, all from pure C(60). Uniformly shaped rhombi and hexagons were obtained at tert-butyl alcohol/toluene and i-propyl alcohol/CCl(4) interfaces, respectively. In addition, exposure of these 2D nanosheets to water induced selective transformation into 1D nanorods. Nanorhombi were converted to short nanorods upon exposure to water. This shape shift is accompanied by changes in crystalline structures from a mixed fcc/hexagonal to pure fcc lattice, the latter of which is almost identical with morphologically similar C(60) nanowhiskers. Metastable nanorhombi which possess a strained mixed crystalline structure metamorphosize into the more stable short nanowhisker (nanorods). In contrast, the stable nanohexagon of a single lattice (and so less strain) does not undergo shape shifting. These results clearly demonstrate controlled formation of 2D nanosheets with various shapes (hexagons, rhombi, etc.) and selective shape shifting to nanorods (short nanowhiskers) all from pure C(60) molecules by very simple solvent treatments.

Paradigm shift from self-assembly to commanded assembly of functional materials: recent examples in porphyrin/fullerene supramolecular systems

“…This strategy has been used for shape-defined fullerene assembly as seen in the formation of fullerene nanowhiskers [60][61][62]. As shown in figure 5, interfacial precipitation of C 60 by the addition of poor solvents into C 60 saturated solutions provides various morphologies of 2D crystals of C 60 [63,64]. The results demonstrate controlled formation of 2D nanosheets of various shapes (hexagons, rhombi, and mixed polygons)-all from pristine C 60 molecules-by a very simple solvent treatment.…”

Self-Assembled Fullerene Nanostructures

“…Rather, whiskers are composed of many C 60 molecules bonded through a combination of van der Waals interactions and chemical bonds. Miyazawa et al have also extended this method to produce 2D hexagonal and polygonal shaped nanosheets 31,32 . Very recently, we extended this method to produce giant microcrystals with macropores at their surfaces and also succeeded in fabricating, for the first time, hexagonal-shaped crystalline fullerene with bimodal pore structures 33,34 .…”

“…For example, hexagonal shape nanosheet with a diameter 7.5 μm was observed in the IPA/CCl 4 system, whereas the diameter decreased to 2.5 μm and 500 nm, respectively with ethanol and methanol. The same group also fabricated polygonal shaped 2D crystals including hexagons and rhombuses by altering solvent molecular structures 32 . As mentioned earlier, Park et al 39 produced 2D crystals of C 60 by a drop-drying method from a so-called pseudo 3D geometry solvent such as CCl 4 and SnCl 4 , which also supports the results of Miyazawa and coworkers.…”

Precise Raman measurements of C₆₀ fullerene nanowhiskers synthesized using the liquid-liquid interfacial precipitation method

“…In our previous articles [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30], the Raman measurements were performed in air to characterize various C60FNWs synthesized by the liquid-liquid interfacial precipitation (LLIP) method [31]. However, the measured Ag(2) peak of C60FNWs varied from 1458 cm -1 to 1468 cm -1 .…”