C₆₀ Solvate with (1,1,2)-Trichloroethane: Dynamic Statistical Disorder and Mixed Conformation

Abstract

We present a full characterization of the orientationally disordered co-crystal of C 60 with (1,1,2)-trichloroethane (C 2 H 3 Cl 3 ) by means of x-ray diffraction, Raman spectroscopy and broadband dielectric spectroscopy. Our results include the determination of molecular conformations, lattice structure, positional disorder, and molecular reorientational dynamics down to the microsecond timescale. We find that, while in the disordered solid phase of pure C 2 H 3 Cl 3 the molecules exist only in the gauche conformation, both gauche and transoid conformers are present in the solvate, * Corresponding author. Tel: +34 934016568. E-mail: roberto.macovez@upc.edu. 2 where they occupy the largest interstitial cavities between the fullerenes species. The two C 2 H 3 Cl 3 conformers exhibit separate, independent relaxations, both characterized by simplyactivated behavior. The relaxation of the transoid conformer, which has twice the dipole moment of the gauche isomer, is significantly slower than that of the latter, due to the high polarizability of C 60 resulting in an electrostatic drag against the reorientations of the dipolar C 2 H 3 Cl 3 species.The observation of two distinct, simply-activated relaxations freezing at distinct temperatures indicates that they are not truly many-body relaxations, which may be rationalized considering that the C 2 H 3 Cl 3 molecules are separated by the relatively bulky C 60 spacers.3

Simultaneous Orientational and Conformational Molecular Dynamics in Solid 1,1,2-Trichloroethane

“…The occurrence and relative concentration of conformers varies according to the nature of the system, and depends on the subtle balance of intramolecular strains and the effects of the molecular environment. 14,[16][17][18] We focus here on (1,1,2)-trichloroethane (hereafter TCE), of molecular formula C 2 H 3 Cl 3 . At ambient pressure, TCE is liquid at room temperature and below 237 K it displays a monoclinic phase, referred to as phase α, characterized by the simultaneous presence of distinct molecular conformers and orientations, accompanied by site disorder close to the melting point.…”

“…(In the transoid isomer of 1,1,2,2-tetrachloroethane, it is actually the hydrogen on carbon 1 and the chlorine on carbon 2 that are in a trans configuration with respect to each another.) The occurrence and relative concentration of conformers vary according to the nature of the system and depend on the subtle balance of intramolecular strains and the effects of the molecular environment. ,− …”

Application of the Consonance Solvent Concept for Accurate Prediction of Buckminster Solubility in 180 Net Solvents using COSMO-RS Approach

“…Unfortunately, in reports providing the values of solubility there are not sufficient information about solid phase present in the equilibrium with the saturated solutions. Although no direct clues about C60 solvates can be inferred from solubility measurements this aspect was not overlooked and attracted serious attention by many investigators [10][11][12][13][14][15][16][17][64][65][66][67][68]. For example, the dissolution properties of C60 in aromatic solvents were studied using the thermos-analytical approach [10,12] and many solid solvates were identified.…”

“…It is also worth mentioning that the reference solvent method cannot help in the cases if solid states in equilibrium with saturated solutions comprise solvates. Since, there is a vast gross of evidences [10][11][12][13][14]16,17,[64][65][66]68] that Buckminster can interact with many solvents, it is quite clear that reference solubility cannot be used neither for serious improvement of predicted solubility data nor for treating cases of unknown fusion characteristics.…”

Physical Properties of Organic Fullerene Cocrystals

“…The structure of the solvate, as obtained by refinement of X-ray powder diffraction (XRPD) data, is shown in Figure 1A. Figure 1B exhibits the relaxation times of the trichloroethane species, as measured by dielectric spectroscopy; two distinct relaxation times are observed (Mitsari et al, 2016b) (since this technique is sensitive to changes of the electric dipole moment, it can be used to selectively probe the motion of the polar ethane derivatives).…”