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

Abstract

SummaryA series of donor–acceptor type co-crystals of fullerene (as the acceptor) and arylthio-substituted tetrathiafulvalene derivatives (Ar-S-TTF, as the donor) were prepared and their structural features were thoroughly investigated. The formation of co-crystals relies on the flexibility of Ar-S-TTF and the size matches between Ar-S-TTF and fullerene. Regarding their compositions, the studied co-crystals can be divided into two types, where types I and II have donor:acceptor ratios of 1:1 and 1:2, respectively. Multiple intermolecular interactions are observed between the donor and acceptor, which act to stabilize the structures of the resulting co-crystals. In the type I co-crystals, the fullerene molecule is surrounded by four Ar-S-TTF molecules, that is, two Ar-S-TTF molecules form a sandwich structure with one fullerene molecule and the other two Ar-S-TTF molecules interact with the fullerene molecule along their lateral axes. In the type II co-crystals, one fullerene molecule has the donor–acceptor mode similar to that in type I, whereas the other fullerene molecule is substantially surrounded by the aryl groups on Ar-S-TTF molecules and the solvent molecules.

Understanding Charge-Transfer Characteristics in Crystalline Nanosheets of Fullerene/(Metallo)porphyrin Cocrystals

“…In contrast to the C 70 nanorods, new absorption peaks appear around 900 nm for C 70 /ZnTPP nanosheets and at around 800 nm for C 70 /H 2 TPP nanosheets (Figure S5). In line with previous studies, these are attributed to charge-transfer (CT) transitions between the electron-donating (metallo)­porphyrins and the electron-accepting C 70 . − …”

“…Cocrystals of fullerene complexes featuring amines, hydrocarbons, and sulfides were described in early publications. − In the resulting electron donor–acceptor systems, a wide range of physical properties, including metallic, photoconducting, magnetic, and even superconductive, have been established. − Important for the self-assembly of fullerene nanoarchitectures are, however, charge-transfer (CT) interactions. − Sizeable intermolecular CT interactions have been corroborated when using electron-donating ferrocenes, (metallo)­porphyrins, porphyrazines, tetrathiafulvalenes, etc., by means of characteristic ground-state absorption features. − …”

Copper ion salts of arylthiotetrathiafulvalenes: synthesis, structure diversity and magnetic properties

“…Most Ar-S-TTFs possess redox potentials higher than that of bis(ethylenedithio)-TTF (BEDT-TTF) [ 33 – 39 ]. Consequently, the complexes of Ar-S-TTFs with electron acceptors such as fullerenes [ 40 – 41 ] and TCNQ [ 42 ] show a neutral ground state. However, Ar-S-TTFs can be chemically oxidized by strong electron acceptors such as F 4 TCNQ [ 42 ] and Keggin-type phosphomolybdic acid [ 43 ] to form CT complexes.…”

A weaker donor shows higher oxidation state upon aggregation

“… 8 Ar-S-TTFs are derived from TTF by decorating four arylthio groups onto the peripheral positions ( Scheme 1 ). Ar-S-TTFs can adjust their geometry and electronic state to adapt to a guest molecule, 9 and they form CT complexes with various acceptors such as fullerene, 10 heteropoly acid, 11 and CuBr 2 . 12 …”