Synthesis and properties of tris-fused donor containing thiopyran ring

Several derivatives of tris-fused donors, 2-(1,3-dithiol-2-ylidene)-2′-(thiopyran-4-ylidene)-5,5′-bi(1,3,4, 6-tetrathiapentalenylidene) (TPDT-TTPY) have been prepared. Cyclic voltammogram of the bis(n-hexylthio) derivative 1b showed four pairs of one-electron redox waves and a pair of two-electron redox one, which is in agreement with the existence of six redox-active sites. The first oxidation potential (E1) of 1b (+0.35 V vs. SCE) is almost equal to that of the corresponding derivative of the bis-fused donor TPDT-TTP (6, +0.36 V). The E2-E1 values of 1b (0.21 V) is smaller by ca. 0.04 V compared with that of 6. The electrical conductivities of their conducting complexes are comparatively high (σrt = 10−2 - 100 S·cm−1).