Aggregation-induced emission (AIE) has been harnessed in many systems through the principle of restriction of intramolecular rotations (RIR) based on mechanistic understanding from archetypal AIE molecules such as tetraphenylethene (TPE). However, as the family of AIE-active molecules grows, the RIR model cannot fully explain some AIE phenomena. Here, we report a broadening of the AIE mechanism through analysis of 10,10',11,11'-tetrahydro-5,5'-bidibenzo[a,d][7]annulenylidene (THBDBA), and 5,5'-bidibenzo[a,d][7]annulenylidene (BDBA). Analyses of the computational QM/MM model reveal that the novel mechanism behind the AIE of THBDBA and BDBA is the restriction of intramolecular vibration (RIV). A more generalized mechanistic understanding of AIE results by combining RIR and RIV into the principle of restriction of intramolecular motions (RIM).

Carbon nanobelts are milestones in the bottom-up approach to challenging chirality-specific synthesis of carbon nanotubes. This study puts forth an unprecedented armchair carbon nanobelt and the first chiral carbon nanobelt, which represent sidewall segments of (12,12)CNT and (18,12)CNT, respectively. These carbon nanobelts were efficiently synthesized by p-expansion of the corresponding polyarylated carbon nanorings through Scholl reactions, which are accompanied by either a small increase or even a decrease in strain energy, as found from the theoretical calculations.

An exploratory study on a group of silylethynylated N‐heteropentacenes as soluble and stable organic semiconductors is presented. An interesting finding is that a silylethynylated N‐heteropentacene can function as a p‐type, n‐type, or ambipolar organic semiconductor depending on the structure of its π‐backbone. The tetraazapentacene derivative is one of the best performing n‐type organic semiconductors with an electron mobility of up to 3.3 cm2 V−1 s−1.