Charge-transfer complexes of sulfur-rich acceptors derived from birhodanines†
Sulfur-rich acceptors, birhodanines, 3,3′-dialkyl-5,5′-bithiazolidinylidene-2,2′-dione-4,4′-dithiones (OS-R, R = Et and Pr) and 3,3′-dialkyl-5,5′-bithiazolidinylidene-4,4′-dione-2,2′-dithiones (SO-R, R = Et), as well as the sulfur analogues, 3,3′-dialkyl-5,5′-bithiazolidinylidene-2,4,2′,4′-tetrathiones (SS-R, R = Et, Pr), form 1 : 1 composition charge-transfer complexes with donors such as pyrene, perylene, and coronene. These complexes have mixed stacks, and the SS-R complexes show n-channel transistor properties due to the intercolumnar S⋯S contacts between the acceptors. By contrast, the OS-R and SO-R complexes exhibit basically hole-dominant ambipolar properties due to the absence of S⋯S contacts. Accordingly, the charge transport is governed mostly by the direct interchain interactions instead of the transport along the columns.