Solvent‐Induced Crystalline‐State Emission and Multichromism of a Bent π‐Surface System Composed of Dibenzocyclooctatetraene Units

Abstract

All bent out of shape: The solvent of crystallization effectively enhances the emission of flexible, bent, π-conjugated molecules in the crystalline state owing to control of the packing of the molecules in the structure. Multichromism such as thermochromism and vapochromism also arises from the solvent-controlled packing. This crystalline-state emission is attributable to the flexibility of cyclooctatetraene units of the bent π-conjugated molecules in the solid state (see figure).

Aggregation-induced emission and aggregation-promoted photochromism of bis(diphenylmethylene)dihydroacenes

“…3 This RIR mechanism has been successfully utilized to explore a large variety of new fluorescent and phosphorescent materials with high luminescence quantum yields in their solid states. However, some newly emerging AIE systems, such as the nonplanar THBA 4 and BCOT 5 (Fig. 1), have an absence of multiple rotors.…”

Bent π‐Conjugated Systems Composed of Three‐Dimensional Benzoannulenes

“…To synthesize 22a , b and 23a , b , the synthetic method can be simplified using C 2 ‐ or C 4 ‐symmetric intermediates. In fact, by employing Fieser's method for DBCOT synthesis,[35] the simple and efficient syntheses of 22a , b and 23a , b were carried out in moderate yields (Scheme ) [20]. We also attempted to synthesize cyano‐substituted [6.8] 4 cyclacene 32 in a one‐step reaction (Scheme ).…”

“…With various DMTs in hand, we first evaluated how the substituent on a COT ring affects the dynamic behavior of DMTs 19a , b , 20a , b , 21b , 22a , b , and 23a , b in solution by VT 1 H NMR measurements [19,20b]. In contrast to unsubstituted DMT 15 , the syn and anti isomers of all substituted DMTs were independently observed at room temperature, and these signals coalesced at high temperatures (>50°C) as shown in Figure , indicating higher isomerization barriers than that of 15 due to the steric hindrance between the substituent (CN, CHO, or CH 2 OMe) and the proton attached to the neighboring benzene ring.…”

“…These DMTs are present as an equilibrium mixture of syn and anti forms categorized as half‐belt and corrugated board, respectively, and the face‐to‐face distance of the two terminal benzene rings in the syn form was calculated to be 6.6 Å. Therefore, the syn ‐DMTs can incorporate a planar guest between the two terminal benzene rings [19,20]…”

Morphology directing synthesis of 1-aminopyrene microstructures and its super quenching effect towards nitro aromatics

“…Driving forces for self assembly are based on different intermolecular forces like van der Waals interaction [17], hydrogen bonding [18], co-ordination bonding, hydrophobic interaction [19], π-π stacking [20] etc. The impact of various intermolecular interactions can be realized as the crystal evolves from a nanoscopic size domain to a microcrystalline and bulk solid.…”