Chemical crystallography of fullerenes

Solid State Physicochemical Properties and Applications of Organic and Metallo- Organic Fullerene Derivatives

“…When mixed with organic molecules or small atomic clusters, therefore, fullerenes readily form van der Waals [47], polar, or ionic [82] molecular compounds (e.g. clathrates, solvates, hydrates) in which the "guest" species accommodated in the space between the globular C 60 molecules so as to maximize the total density.…”

“…The first one is represented by non-covalently bonded complexes of fullerenes with different molecules ranging from porphyrines to light harvesting dendrimers, to solvates and hydrates of C 60 or higher fullerenes [47]. A second one is represented by all-carbon nanotubes-fullerene macromolecular hybrids such as peapods [48] and covalently-linked hybrids [43], and all-C 60 polymer chains and networks observed in solid C 60 phases.…”

Physical Properties of Organic Fullerene Cocrystals

“…While small, symmetric intercalants can preserve the closepacked structure of the fullerene species, resulting in crystal structures that are often cubic or hexagonal, most fullerene cocrystals display a more open and less symmetric structure (Neretin and Slovokhotov, 2004;Wang, 2015). This is the case of cocrystals with molecules of size comparable to that of the C60 molecule [whose van der Waals diameter is ≈10 Å (Heiney et al, 1991)], but also with smaller aromatic molecules, and even with some tetragonal molecules such as P4 and CCl4.…”

“…This is the case of cocrystals with molecules of size comparable to that of the C60 molecule [whose van der Waals diameter is ≈10 Å (Heiney et al, 1991)], but also with smaller aromatic molecules, and even with some tetragonal molecules such as P4 and CCl4. In many cases, both for high-and low-symmetry lattices, the crystal structure of fullerene cocrystals can be described as consisting of alternating layers of fullerenes and cocrystallizing species (Spitsina et al, 2002;Neretin and Slovokhotov, 2004;Cui et al, 2012;Mitsari et al, 2016a;Ye et al, 2017).…”

“…The hollow molecular structure of fullerenes allows, for example, endohedral complex formation, while their polyconjugated electronic structure enables multiple functionalization with covalently attached adducts (up to one adduct per carbon atom in the case of small groups, which for Buckminsterfullerene means up to 60 adducts) (Taylor and Walton, 1993). A third route for "tuning" fullerenes is cocrystal formation with other organic species in the solid state (Sundqvist, 2003;Neretin and Slovokhotov, 2004;Wang, 2015) or supramolecular complex-formation exploiting π stacking interactions (Fernández et al, 2008;Babu et al, 2010). These three modification routes have been termed, in the case of salts of fullerenes with electron donor atoms or molecules such as alkali atoms or ferrocene, "endohedral, " "on-ball, " and "exohedral, " respectively.…”