Herein, we report the synthesis, structural analysis, optical and chiroptical properties of a novel quadruple helicene, which has two [6] and two [7]helicene moieties fused in a contorted framework of 92 sp2 carbon atoms. It was synthesized by the Scholl reaction of a perylene‐containing substrate with the formation of eight carbon‐carbon bonds on the perylene unit in a single synthetic operation. Chemical oxidation of the quadruple helicene with tris(4‐bromophenyl)ammoniumyl hexachloroantimonate resulted in an air‐stable dication, which exhibits the same helicity in its four helicene moieties as unambiguously identified by single‐crystal X‐ray crystallography. The quadruple helicene exhibits unusual near‐infrared absorption and emission with absorption and emission maxima at 848 nm and 977 nm, respectively, and its isolated enantiomers exhibit electronic circular dichroism in the near‐infrared and visible‐light regions.

This paper describes a simple and low-pollution surface modification strategy for fabricating flexible, semi-transparent, and robust bacterial cellulose (BC)/Kombucha tea-based BC films that are effectively resistant to water, water vapor, oxygen, ultraviolet light, and foodborne pathogenic bacteria. The strategy uses dimethyl sulfoxide as the pre-swelling solvent and long-chain alkenyl succinic anhydrides with different chain lengths as the esterifying agents. The proof of esterification, crystallinity index, film microstructure, and degree of surface substitution were systematically investigated. Our result showed that acylation with 2-octenylsuccinic anhydride for 8 h conferred the BC films with the highest water-vapor/oxygen resistance and optimal mechanical/thermal properties. In addition, the modified BC film has good antimicrobial properties and is capable of wrapping strawberries, increasing their longevity. Biodegradation and alkaline hydrolysis tests demonstrated that compostability of the film and recycling of the BC pulp are possible, revealing that such high-performance biofilm-based food packaging could have a green life cycle.

No abstract

No abstract