脂肪酶催化开环聚合的研究进展

酶是一种绿色、安全、高效、专一的生物催化剂,在反应中具有能耗小、可循环利用和选择性高等优点,更重要的是酶催化聚合能够制备传统的化学催化无法(或难以)实现的聚合物,具有一定的工业化前景。本文简述了酶催化的发展历程、机理以及其制备特殊结构和功能聚合物材料的特点,特别是脂肪酶催化下的开环聚合相对于缩聚反应来说,具有反应条件温和、分子量和结构可控性好等优势,因此重点描述脂肪酶催化开环聚合在合成不同拓扑结构(线型、支化、交联)聚合物中的研究进展。     

Controllably Growing Topologies in One-shot RAFT Polymerization via Macro-latent Monomer Strategy

The controlled and efficient synthesis of polymers with tailored topologies is challenging but important for exploring structure/property research. Herein, we proposed a concept of macro-latent monomer to achieve the controlled growth of polymer topologies.The macro-latent monomer was installed by a dynamic furan/maleimide covalent bond at the chain terminal. One-shot reversible additionfragmentation chain transfer(RAFT) polymerization of styrene and the macro-latent monomer created controlled growth of polymer topologies.Low temperature such as 40 ℃ could not activate the macro-latent monomer and thus the polymerization created the homo-polystyrene. By contrast, high temperature of ～110 ℃ activated the macro-latent monomer, and a maleimide-terminated macro-monomer was released via the retro-Diels Alder reaction. This macro-monomer immediately joined the cross polymerization with styrene and thus produced the side chains. By delicately manipulating the polymerization temperature, the predetermined placement of the macro-latent monomer-derived polymeric sidechains created controllably growing topologies, including star-, π-shaped, and density-variable grafting copolymers. This work paved a new way for creating on-demand topologies and would greatly enrich the topology synthesis.     

Construction of 1D and 2D Zinc Coordination Polymers Based on Organic Carboxylate Anions and Flexible Imidazole‐Containing Ligand

Two novel zinc coordination polymers {[Zn(PhCOO)₂(bmix)]}_n 1 and {[Zn(ada)(bmix)]·(H₂O)₂}_n 2 (bmix = 1,4‐bis(2‐methylimidazole‐1‐ylmethyl)benzene, H₂ada = adipic acid), were obtained by the hydrothermal reactions of bmix and zinc acetate with two carboxylate anions, respectively. Structural analyses show that complex 1 possess a one‐dimensional helix chain structure, 2 takes two‐dimensional corrugated (4,4) layer motif. The structural differences of two complexes indicate that organic carboxylate anions play important roles in the formation of such zinc(II) coordination architectures.     

模糊共生结构的加细及其性质

介绍模糊拓扑,模糊邻近,模糊拟一致框架下的模糊(半)拓扑序、模糊共生结构的概念,研究模糊(半)拓扑序,模糊共生结构的加细,得到一些重要性质。     

Extension of Non-alternant Nanographenes Containing Nitrogen-Doped Stone-Thrower-Wales Defects

Non-alternant topologies have attracted considerable attention due to their unique physiochemical characteristics in recent years. Here, three novel topological nanographenes molecular models of nitrogen-doped Stone–Thrower–Wales (S–T–W) defects were achieved through intramolecular direct arylation. Their chemical structures were unambiguously elucidated by single-crystal analysis. Among them, threefold intramolecular direct arylation compound (C₄₂H₂₁N) is the largest nanographene bearing a N-doped non-alternant topology to date, in which the non-benzenoid rings account for 83 % of the total molecular skeleton. The absorption maxima of this compound was located in the near-infrared region with a long tail up to 900 nm, which was much longer than those reported for similarly sized N-doped nanographene with six-membered rings (C₄₀H₁₅N). In addition, the electronic energy gaps of these series compounds clearly decreased with the introduction of non-alternant topologies (from 2.27 eV to 1.50 eV). It is noteworthy that C₄₂H₂₁N possesses such a low energy gap (E_g^opt=1.40 eV; E_g^cv=1.50 eV), yet is highly stable under ambient conditions. Our work reported herein demonstrates that the non-alternant topology could significantly influence the electronic configurations of nanocarbons, where the introduction of a non-alternanting topology may be an effective way to narrow the energy gap without extending the molecular π-conjugation.