BN versus CC: How Similar Are They?

One of these bonds is not like the others: Cyclic π systems in which BN units replace their isoelectronic CC counterparts have intrigued chemists and materials scientists for decades. The recent report of Piers et al. on the synthesis, crystal structure, and optical properties of 10a-aza-10b-borapyrenes (see picture) represents a major breakthrough in this field.