Inclusion complexes of fullerenes with flexible tetrathiafulvalene derivatives bearing four aryls through sulfur bridges

Abstract

TTF derivatives decorated with four aryls through the sulfur bridges are employed to form the donoracceptor type inclusion complexes with fullerenes. The key factor for the formation of inclusion complexes is the introduction of structural flexibility in TTF molecules along with the molecular size matching with fullerenes. A crystallographic study indicates that the structures of the resulting complexes are stabilized by a multidimensional intermolecular interaction network consisting of TTF cores, peripheral aryls, and fullerenes, which in turn gives rise to the electronic communication between the donor and the acceptor as proved by the solid state absorption spectra. Moreover, the fullerene molecules form the two-dimensional sheet structure in the complexes.

Donor–acceptor type co-crystals of arylthio-substituted tetrathiafulvalenes and fullerenes

“…On the basis of hundreds of experimental runs, we found that the Ar-S-TTFs possessing the first redox potential ( E 1/2 1 ) smaller than 0.6 V could form the co-crystal-type complexes with fullerene molecules C 60 and/or C 70 , whereas those with E 1/2 1 > 0.6 V could not afford the desired complexes. The complexes obtained thus far are intrinsically neutral [ 63 ], which means the charge transfer does not take place between Ar-S-TTF and fullerenes in the ground state. In this regard, the E 1/2 1 values of Ar-S-TTFs would not affect the formation of co-crystals.…”

“… a CS 2 : carbon disulfide, PhCl: chlorobenzene; b the compositions of the co-crystals were determined by X-ray single crystal structure analysis; c see reference [ 63 ]. …”

“…On the other hand, all of the type II co-crystals contain solvent molecules in their matrix. Since one Ar-S-TTF is capable of encapsulating a fullerene molecule [ 63 ], the larger ratio of fullerenes would result in the formation of additional void space by fullerene molecules, which could potentially accommodate the solvent molecules. In a previous report, we have proposed that C 70 tends to form co-crystals with a larger acceptor ratio [ 63 ].…”

“…Since one Ar-S-TTF is capable of encapsulating a fullerene molecule [ 63 ], the larger ratio of fullerenes would result in the formation of additional void space by fullerene molecules, which could potentially accommodate the solvent molecules. In a previous report, we have proposed that C 70 tends to form co-crystals with a larger acceptor ratio [ 63 ]. However, the present results suggest that this prediction would not hold because both C 60 and C 70 form the type I and type II co-crystals with Ar-S-TTFs as shown in Table 1 .…”

“…Regarding the structural feature of Ar-S-TTF, we have performed the complexation of Ar-S-TTFs with C 60 /C 70 , and found that Ar-S-TTF could form D–A type inclusion complexes with C 60 /C 70 [ 63 ]. Crystallographic investigation reveals that the multidimensional interaction networks consisting of a central TTF core, peripheral aryls, and fullerenes are the key factors to stabilize the resulting supramolecular structures.…”