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<middle dot><middle dot><middle dot>S contacts, resulting in parallel face-to-face packing and pi-pi stacking. Double N<middle dot><middle dot><middle dot>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<middle dot><middle dot><middle dot>H & horbar;C networks with pi-pi 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 pi-systems. Brominated one exhibits polymorphs, which works N<middle dot><middle dot><middle dot>Br contacts or Br<middle dot><middle dot><middle dot>Br contacts based on the interaction of the sigma-hole of bromide. These investigations can be applied to the order-made synthesis of self-assembled soft matter and functional molecular crystals.