Crystal Structures of Highly Electron-Accepting Naphtho[1,2-c:5,6-c]bis[1,2,5]Chalcogendiazole

Naphtho[1,2-c:5,6-c]bis[1,2,5]chalcogendiazole is an important building block for organic devices due to its highly electron-accepting properties. However, despite being an effective unit of low band gap organic semiconductors, fewer studies have been conducted on analyzing such units to understand their crystal structure. Here the crystal structure analysis of naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole, naphtho[1,2-c:5,6-c]bis[1,2,5]oxadiazole is reported, and these brominated motifs. Crystal structures of naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazoles and its brominated compound show that the molecules form coplanar structures through N···S contacts, resulting in parallel face-to-face packing and π-π stacking. Double N···S contacts are found as a priority in such compounds. On the other hand, naphtho[1,2-c:5,6-c]bis[1,2,5]oxadiazoles gave N···H─C networks with π-π stacking. These differences will probably induce the difference in the crystal structure of the naphtho[1,2-c:5,6-c]bis[1,2,5]chalcogendiazole-based extended π-systems. Brominated one exhibits polymorphs, which works N···Br contacts or Br···Br contacts based on the interaction of the σ-hole of bromide. These investigations can be applied to the order-made synthesis of self-assembled soft matter and functional molecular crystals.