A Flexible Cyclophane: Design, Synthesis, and Structure of a Multibridged Tris-tetrathiafulvalene (TTF) Macrocycle

Abstract

The tris-tetrathiafulvalene (TTF) macrocycles 3 with a large end-cavity were effectively synthesized from the readily available tetrakis(cyanoethylthio)TTF by means of a selective deprotection/realkylation sequence followed by an intramolecular coupling reaction. Crystar structure analyses revealed that the neutral molecules include two (3a) or one chloroform molecule (3b) as solvent of crystallization inside the cavity, whereas the I3- salt of 3b, obtained by electrocrystallization, has a molecular structure which is different from that of the neutral molecule in that the cavity has completely collapsed.

Tetrathiafulvalene Cyclophanes and Cage Molecules

“…A comparison of the structure of the neutral TTF cage molecule 65 with the structure of the oxidized 65 + showed that the two forms adopt completely different molecule shapes. The neutral end cavity that encapsulated one CHCl 3 molecule in the neutral 65 collapses completely upon oxidation as depicted in Figure , and the oxidized molecule 65 + folds to effectively minimize the volume of cavity . These observations clearly illustrate that intramolecular interactions between the cationic and neutral TTF units are taking place and play an important role in the stabilization of the collapsed molecular shape of 65 + .…”

“…Hydrogen atoms are omitted for clarity. (Reprinted with permission from ref . Copyright 2000 Wiley-VCH.)…”

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17 Synthesis of the Tris-TFF Cage Molecule 65

21 CPK model describing the change in the shape of the cavity in the tris-TTF cage molecule 65 upon oxidation. (Reprinted with permission from ref . Copyright 2000 Wiley-VCH.

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Crystal structures and optical properties of cation radical salts of a tetrathiafulvalene trisannulated macrocycle

“…Recently, a criss-cross tris-TTF cyclophane with C 1 symmetry has been reported. 9 The crystal structures of this neutral donor molecule and cation radical salt of the I 3 2 counter anion showed redox active conformational change. 9 We employed here the tris(DMT-TTF) having C 3 molecular symmetry as a TTF trisannulated macrocycle (Chart 1).…”

“…9 The crystal structures of this neutral donor molecule and cation radical salt of the I 3 2 counter anion showed redox active conformational change. 9 We employed here the tris(DMT-TTF) having C 3 molecular symmetry as a TTF trisannulated macrocycle (Chart 1). 7a The linkers between three DMT-TTF units are propyldithio groups, ±S±(CH 2 ) 3 ±S±.…”