K. Takimiya et al., A flexible cyclophane: Design, synthesis, and structure of a multibridged tris-tetrathiafulvalene (TTF) macrocycle, CHEM-EUR J, 6(11), 2000, pp. 1947-1954
The tris-tetrathiafulvalene (TTF) macrocycles 3 with a large end-cavity wer
e effectively synthesized from the readily available tetrakis(cyanoethylthi
o)TTF by means of a selective deprotection/realkylation sequence followed b
y an intramolecular coupling reaction. Crystal structure analyses revealed
that the neutral molecules include two (3a) or one chloroform molecule (3b)
as solvent of crystallization inside the cavity, whereas the I-3(-) salt o
f 3b, obtained by electrocrystallization, has a molecular structure which i
s different from that of the neutral molecule in that the cavity has comple
tely collapsed.