Chalcogenacalix[4]dithienoselenophene: Synthesis and Properties of Cyclic Thio- and Selenoether of Dithienoselenophene

Two kinds of thia- and selenacalix[4]dithienoselenophene, a cyclic dithieno[3,2-b:2′,3′-d]selenophene (DTS) oligomers bridged with divalent chalcogen atoms (S or Se), were successfully prepared via a one-pot cyclization protocol. A palladium-catalyzed coupling of dibromo DTS derivative and (Bu3Sn)2Ch (Ch = S or Se) afforded the cyclic compounds in moderate yield. We have also developed a preparation strategy for the starting DTS derivatives in multi-gram quantity. X-ray analysis revealed that these macrocyclic compounds have different conformations depending on the linker atoms. Thiacalix derivatives form an annular geometry consisting of two sets of vertical and horizontal DTS pairs, while selenacalix derivatives forms a highly symmetrical alternate arrangement of DTS units. The latter macrocycle gave a channel framework to form cavity assembled porous material. Cyclic voltammetry and differential pulse voltammetry measurements for these macrocycles indicated lower redox potentials compared to those of dithienothiophene analogues reported before. Both compounds form a 1:2 complex with C60 in the solid state through face-to-face and S⋯π interactions between DTS and C60. Two guest C60 molecules were captured in the identical space formed by a symmetrical 1,3-alternate conformer. Two kinds of chalcogenacalix[4]dithienoselenophene, a cyclic dithieno[3,2-b:2′,3′-d]selenophene oligomers bridged with S or Se, were prepared. The X-ray analysis revealed a horizontal or a 1,3-alternate conformation. The latter gave a channel framework to form a cavity assembled porous material. Both compounds form a 1:2 complex with C60 in the solid state through face-to-face and S…π interactions.