Crystal-Rigidifying Strategy in Hybrid Manganese Halide to Achieve Narrow Green Emission and High Structural Stability.

Although organic-inorganic hybrid Mn2+ halides have advanced significantly, achieving high stability and narrow-band emission remains enormously challenging owing to the weak ionic nature and soft crystal lattice of the halide structure. To address these issues, we proposed a cationic engineering strategy of long-range cation π···π stacking and C-H···π interactions to simultaneously improve the crystal structural stability and rigidity. Herein, two organic zero-dimensional (0D) manganese halide hybrids of (BACQ)2MnX4 [BACQ = 4-(butylamino)-7-chloroquinolin-1-ium; X = Cl and Br] were synthesized. (BACQ)2MnX4 display strong green-light emissions with the narrowest full width at half-maximum (fwhm) of 39 nm, which is significantly smaller than those of commercial green phosphor ß-SiAlON:Eu2+ and most of reported manganese halides. Detailed Hirshfeld surface analyses demonstrate the rigid environment around the [MnX4]2- units originating from the interactions between [BACQ]+. The rigid crystal structure weakens the electron-phonon coupling and renders narrow fwhm of these manganese halides, which is further confirmed by temperature-dependent emission spectra. Remarkably, (BACQ)2MnX4 realizes outstanding structural and luminescence stabilities in various extreme environments. Benefiting from the excellent performance, these Mn2+ halides are used to assemble light-emitting diodes with a wide color gamut of 105% of the National Television System Committee 1931 standard, showcasing the advanced applications in liquid-crystal-display backlighting.

Flavonoids from Mirabilis himalaica.

Six previously undescribed flavonoids, 2S-5-methoxy-6-methyl-7,2'-dihydroxyflavanone, 5,7,2'-trihydroxy-6-methylflavone, 5,7,6'-trihydroxy-6-methylcoumaronochromone, 2,4',6'-trihydroxy-2'-methoxy-3'-methylchalcone, 6R,11-dimethoxy-9-hydroxyrotenoid, and 6R,11-dimethoxy-9-hydroxy-10-methylrotenoid, along with eight known flavonoids, including 2S-5-methoxy-6-methyl-7,4'-dihydroxyflavanone, not previously reported as a natural product, and seven rotenoids, boeravinone A, B, D, P, F, coccineone B, and mirabijalone E, were isolated from the ethyl acetate soluble fraction of Mirabilis himalaica roots. Their structures were established by the extensive spectroscopic analysis, including HRESIMS, UV, NMR and ECD. All compounds were evaluated for their cytotoxic activities against three human cancer cell lines: A375 (melanoma), A549 (lung), and PLC (hepatoma).