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To design ultrabright fluorescent solid dyes, a crystal engineering strategy that enables monomeric emission by blocking intermolecular electronic interactions must be developed. We introduced propylene moieties in distyrylbenzene (DSB) as a bridge between the two phenyl rings around its C=C bonds. The bridged DSB derivatives formed compact crystals and exhibited emission colors similar to those of dilute solutions with high quantum yields. The introduction of flexible seven-membered rings into the DSB core resulted in moderate distortion and steric hindrance in the π-plane of DSB. However, the molecular arrangement could be controlled with almost no decrease in the crystal density relative to that of DSB, and the electronic interactions were suppressed. The crystal structure of bridged DSB was different from those of other DSB derivatives, indicating that bridging afforded novel crystalline systems. This design strategy has important implications in many fields and is more effective than conventional photofunctional crystal design strategies.

ABTRACTReddish coloration and color diversity among icy bodies in the outer solar system are one of the significant clues for understanding the status and history of the solar system. However, the origin of color distribution remains debatable. Here, we demonstrate reddish coloration that is stable only at cryogenic temperatures in a laboratory experiment. The reddish coloration was produced on methanol-and water-containing ice irradiated with nitrogen-containing cryoplasma at 85 K. The reddish color visually faded and disappeared at 120-150 K as the ice was heated, unlike well-known refractory organic tholins that are stable even when heated to room temperature. This temperature dependence of reddish coloration under cryogenic conditions could provide a new possible explanation for the absence of ultra-red coloration closer to the Sun in the outer solar system. Our result implies that a reddish material specific to cryogenic environments is useful for the investigation of color diversity and formation mechanism of the outer solar system.3

Photocatalytic CO2 reduction is in high demand for sustainable energy management. Hybrid photocatalysts combining semiconductors with supramolecular photocatalysts represent a powerful strategy for constructing visible-light-driven CO2 reduction systems with strong oxidation power. Here, we demonstrate the novel effects of plasma surface modification of graphitic carbon nitride (C3N4), which is an organic semiconductor, to achieve better affinity and electron transfer at the interface of a hybrid photocatalyst consisting of C3N4 and a Ru­(II)–Ru­(II) binuclear complex (RuRu′). This plasma treatment enabled the “surface-specific” introduction of oxygen functional groups via the formation of a carbon layer, which worked as active sites for adsorbing metal-complex molecules with methyl phosphonic-acid anchoring groups onto the plasma-modified surface of C3N4. Upon photocatalytic CO2 reduction with the hybrid under visible-light irradiation, the plasma-surface-modified C3N4 with RuRu′ enhanced the durability of HCOOH production by three times compared to that achieved when using a nonmodified system. The high selectivity of HCOOH production against byproduct evolution (H2 and CO) was improved, and the turnover number of HCOOH production based on the RuRu′ used reached 50 000, which is the highest among the metal-complex/semiconductor hybrid systems reported thus far. The improved activity is mainly attributed to the promotion of electron transfer from C3N4 to RuRu′ under light irradiation via the accumulation of electrons trapped in deep defect sites on the plasma-modified surface of C3N4.