Physical Properties of Organic Fullerene Cocrystals

Abstract

The basic facts and fundamental properties of binary fullerene cocrystals are reviewed, focusing especially on solvates and salts of Buckminsterfullerene (C60), and hydrates of hydrophilic C60 derivatives. The examined properties include the lattice structure and the presence of orientational disorder and/or rotational dynamics (of both fullerenes and cocrystallizing moieties), thermodynamic properties such as decomposition enthalpies, and charge transport properties. Both thermodynamic properties and molecular orientational disorder shed light on the extent of intermolecular interactions in these binary solid-state systems. Comparison is carried out also with pristine fullerite and with the solid phases of functionalized C60. Interesting experimental findings on binary fullerene cocrystals include the simultaneous occurrence of rotations of both constituent molecular species, crystal morphologies reminiscent of quasicrystalline behavior, the observation of proton conduction in hydrate solids of hydrophilic fullerene derivatives, and the production of super-hard carbon materials by application of high pressures on solvated fullerene crystals.

Putting Fullerenes in Their Place: Cocrystallizing C60 and C70 with Phosphangulene Chalcogenides

“…Despite the inherently inefficient packing of globular objects, fullerenes have characteristically low solubility, which reflects poor solvation, as well as stabilization of their crystal lattices by extensive intermolecular aromatic interactions. Nevertheless, many cocrystals of fullerenes have been reported, often with partners that incorporate extended hinged or curved aromatic surfaces. − In particular, Yamamura, Nabeshima, and co-workers have prepared complex derivatives of phosphangulene that form cocrystals with C 60 and C 70 . − …”

An order–disorder phase transition in the van der Waals based solvate of C60 and CClBrH2

“…[4][5][6][7] In particular co-crystals and solvates, formed by intercalation of organic or inorganic molecules or even metals into the fullerene structures, have acquired a renewed interest during the last decade. 8,9 This is because solvates, or more precisely hexagonal close packed solvates, tend to easily form nanowires not only with high conductivity but also with extraordinary mechanical properties, as has been demonstrated by the discovery of incompressible phases, which are harder than diamond at high pressure. 3,8,10 In these systems, the superior mechanical properties are related to the 3D network of covalently bonded C atoms between rigid C 60 molecules together with dopant molecules acting as a spacer between C 60 units and as a linker between collapsed C 60 units.…”

The intermolecular anthracene-transfer in a regiospecific antipodal C60difunctionalization

“…The experimental work on the fullerene functionalization has been accompanied and guided by insightful theoretical studies. [27][28][29][30] Suitably functionalized fullerenes have been widely applied as key components, [31][32][33][34] in photovoltaic devices, [35][36][37][38][39] in artificial photosynthesis, 40,41 drug delivery, 32,42 bio-and nanomedicine, 41,42 in material science, 31,[43][44][45][46][47][48] and as self-healing polymers. 49,50 The molecular features of the fullerenes as polyunsaturated spherical carbon compounds have drawn particular attention to the synthesis of di-and multi-functionalized derivatives with high regio-and stereo-control.…”