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Lignin condensation reactions are hard to avoid or control during separation, which is a deterrent to lignin isolation and post‐conversation, especially for the full utilization of lignocelluloses. Selective protection of β‐aryl ether linkages in the isolation process is crucial to lignin valorization. Herein, a two‐step acid/alkali separation method assisted with l‐cysteine for eucalyptus lignin separation is developed, and the isolated l‐cysteine lignins (LCLs) are comprehensively characterized by 2D NMR, 31P NMR, thioacidolysis, etc. Compared to the two‐step control treatment, a much higher β‐O‐4 content is preserved without reducing the separation efficiency assisted by l‐cysteine, which is also significantly higher than alkali lignin and kraft lignin. The results of hydrogenolysis show that LCLs generate a much higher monomer yield than that of control sample. Structural analysis of LCLs suggests that lignin condensation reaction, to some extent, is suppressed by adding l‐cysteine during the two‐step acid/alkali separation. Further, mechanistic studies using dimeric model compound reveals that l‐cysteine may be the α‐carbon protective agent in the two‐step separation. The role of l‐cysteine in the two‐step lignin isolation method provides novel insights to the selective fractionation of lignin from biomass, especially for the full valorization of lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

Phenolation is a commonly used method to improve the reactivity of lignin for various applications. In this study, resinol lignin models (syringaresinol and pinoresinol) and eucalyptus alkali lignin were treated under acid‐catalyzed phenolation conditions to investigate the products derived from resinol (β–β) structures of lignins. The phenolation products were characterized by means of GC‐MS and NMR spectroscopy following separation using flash chromatography and thin‐layer chromatography. A series of new naphthalene products were identified from phenolation of syringaresinol, and the corresponding guaiacyl analogs were also identified by GC‐MS. The C1−Cα bond of these resinol compounds was cleaved to release syringol or guaiacol during phenolation. In addition, diphenylmethane products formed from phenol or phenol and syringol/guaiacol were found in the phenolation products. Comparatively, more naphthalene products were obtained by phenolation from syringaresinol than those obtained from pinoresinol. HSQC NMR characterization of the phenolated alkali lignin revealed that naphthalene structures formed in the phenolated lignin. [ABSTRACT FROM AUTHOR]

Abstract: Chlorinated conjugated polymers not only show great potential for the realization of highly efficient polymer solar cells (PSCs) but also have simple and high‐yield synthetic routes and low‐cost raw materials available for their preparation. However, the study of the structure–property relationship of chlorinated polymers is lagging. Now two chlorinated conjugated polymers, PCl(3)BDB‐T and PCl(4)BDB‐T are investigated. When the polymers were used to fabricate PSCs with the nonfullerene acceptor (IT‐4F), surprisingly, the PCl(3)BDB‐T:IT‐4F‐based device exhibited a negligible power conversion efficiency (PCE) of 0.18 %, while the PCl(4)BDB‐T:IT‐4F‐based device showed an outstanding PCE of 12.33 %. These results provide new insight for the rational design and synthesis of novel chlorinated polymer donors for further improving the photovoltaic efficiencies of PSCs. [ABSTRACT FROM AUTHOR]