New Insights into the Structural Complexity of C₆₀·2S₈: Two Crystal Morphologies, Two Phase Changes, Four Polymorphs

Abstract

Three new polymorphs of C 60 •2S 8 were discovered. The previously known structure (first reported by Roth and Adelmann in 1993 hereby designated as α) crystallizes in space group C2/c with Z = 4 and changes to a triclinic structure (β) in space group P1̅ with Z = 4 when the temperature is decreased below 260 K. The room-temperature structure was reinvestigated, and the new, ordered, lowtemperature structure is described. A new, concomitant, polymorph (γ) crystallizes in space group P2 1 /c with Z = 4 at room temperature and undergoes a phase change to Pc (δ) with Z = 4 when the temperature is decreased below 180 K. As indicated by geometric and temperature factor changes, it is clear that the low-temperature phases represent an increase in the level of order in the arrangement of C 60 molecules. Both of the phase changes are reversible.

Metal Ion Effects on Fullerene/Porphyrin Cocrystallization

“…Crystals started appearing within 24 h, but they were allowed to grow for about 2 weeks to achieve the size we wanted for data collection. As done in previous studies, , we carefully examined the morphology and diffraction from many crystals for each of the four different cocrystals. Only one type of cocrystal was found for each of the four different metalloporphyrins.…”

Caught in Phase Transition: Snapshot of the Metallofullerene Sc3N@C70 Rotation in the Crystal

“…Typically, the fullerene/NiOEP cocrystals show a gradual increase of librational amplitudes of the fullerene cage in a broad temperature range without a clear structural transition, such as found in Lu 3 N@C 80 /NiOEP or HoLu 2 N@C 80 /NiOEP . The phase transition of fullerene crystals was observed for several cases, such as Li@C 60 /NiOEP, C 70 /NiOEP, C 60 /S 8 , C 60 /CS 2 , C 60 /C 6 H 6 , C 60 /C 2 Cl 4 , or C 60 itself . Although the existence of different phases was clearly identified, the microscopic details of the transition process between these phases were rarely traced.…”

Rotation of fullerene molecules in the crystal lattice of fullerene/porphyrin: C60 and Sc3N@C80

“…This is likely owned to the challenges presented by the need for high-quality crystals and technical effort required to undertake variable temperature X-ray diffraction measurements (VT-XRD). Phase transitions in crystals containing fullerenes were observed for several cases, such as, Li@C 60 /NiOEP, 12 C 60 /S 8 , 13 , C 60 /CS 2 , 14 C 60 /C 6 H 6 , 15 C 60 /C 2 Cl 4 . 16 C 60 /CoOEP was reported more than two decades ago.…”