Use of chiral solvents in asymmetric synthesis as a sole source of enantioselection remains largely unexplored in organic synthesis. We found that the use of a helical macromolecular catalyst of which helical chirality is dynamically formed in chiral solvents allowed several mechanistically different reactions to proceed with high enantioselectivity. In this system, the chirality of the solvent, such as limonene, induces a configurational imbalance to the helical macromolecular scaffold of the catalyst, and in turn to the reaction products through palladium-catalyzed asymmetric reactions including Suzuki-Miyaura cross-coupling (up to 98% ee), styrene hydrosilylation (up to 95% ee), and silaboration (up to 89% ee). Not only enantiomerically pure limonene but also limonene with low enantiomeric excesses induce single-handed helical structures with majority-rule-based amplification of homochirality. The helical conformation of the macromolecular catalyst was retained even in the absence of limonene in the solid state, enabling asymmetric cross-coupling in achiral solvent with high enantioselectivity.

This publisher’s note contains corrections to Opt. Lett. 45, 495 (2020)OPLEDP0146-959210.1364/OL.376894.

AlGaN-based ultraviolet-A (UVA) light-emitting-diodes (LEDs) at emission under 330 nm are of great importance for numerous applications, including medicine and photochemical technologies. In this Letter, a highly relaxed n-AlGaN electron injection layer (EIL) underneath the multi-quantum wells (MQWs) for the suppression of both threading dislocation densities and piezoelectric effect was attempted. When the Ga-rich n-AlGaN EIL in the UVA LED was relaxed up to 75%, the full width at half-maximum values of the X-ray rocking curves for the (10–12) planes were reduced from our previous value of approximately 793 to 564 arcsec. Subsequently, a maximum light power of 3.1 mW was achieved in the 326 nm band UVA LED. However, carrier confinement and transport issues in the MQWs were observed. To resolve these issues of carrier confinement and transport, we provide a short roadmap for experimental efforts to realize an internal quantum efficiency (IQE) beyond 53% in AlGaN UVA-MQWs.

Poly(quinoxaline-2,3-diyl)s with chiral (S)-2-butoxymethyl side chains dissolved in 1,2-dichloroethane experience a reversible pressure-dependent helix inversion from P- to M-helical structures between 0.1 MPa and 200 MPa.