CO2-Driven stereochemical inversion of sugars to create thymidine-based polycarbonates by ring-opening polymerisation
CO2-Driven stereochemical inversion of sugars to create thymidine-based polycarbonates by ring-opening polymerisation
复制标题
DOI：
10.1039/c7py00118e
复制
发表时间：
2017-03-14
影响因子：
4.6
通讯作者：
Buchard, Antoine
中科院分区：
文献类型：
--
作者：
Gregory, Georgina L.;Hierons, Elizabeth M.;Buchard, Antoine
从可再生资源中开发可生物降解的聚合物对于解决塑料对石油基原料的依赖以及不断增长的海洋和垃圾填埋场废物至关重要。在本文中，CO2和天然糖二醇都被用作合成可降解和生物相容的脂肪族聚碳酸酯的丰富、安全和可再生的结构单元。尽管受到自然界超分子碱基配对的启发，来自DNA的糖组分的聚碳酸酯具有先进的聚合物性质的强大潜力，但2'-脱氧核糖核苷受到光气衍生物不能形成允许受控开环聚合的环状碳酸酯单体的限制。在1个大气压下，CO2插入甲基化胸苷2'-脱氧核糖核苷中，由有机碱1，8-二氮杂双环-[5.4.0]-十一碳-7-烯促进，影响了分子内对甲苯磺酰基离去基团的SN2样置换，通过立体化学转化产生环状碳酸酯。有机催化开环聚合在溶液中快速进行，导致93%的高单体转化率和数均分子量，比通过缩聚途径显著更大和更可控。聚合的热力学参数（Δ H-p =-12.3 +/-0.4kJ mol（-1）和Δ S-p =-29 +/-1.1J mol（-1）K-1）由0 - 80 ℃温度范围内的平衡单体转化率确定，并证明了伪一级动力学。无定形胸苷基聚碳酸酯表现出156 ° C的高玻璃化转变温度，并且发现在碱性水性条件下可高度降解为组分二醇。静态水接触角测量和MG-63细胞系的细胞研究表明，轻微的亲水性和生物相容性材料，有希望的组织工程应用。这种新型的、CO2驱动的环状碳酸酯合成方法代表了一种扩大糖基单体范围的方法，用于定制来自天然产物的材料特性。
The development of biodegradable polymers from renewable resources is vital in addressing the dependence of plastics on petroleum-based feedstocks and growing ocean and landfill waste. Herein, both CO2 and natural sugar diols are utilised as abundant, safe and renewable building blocks for the synthesis of degradable and biocompatible aliphatic polycarbonates. Despite a strong potential for advanced polymer properties, inspired by Nature's supramolecular base-pairing, polycarbonates from the sugar components of DNA, 2'-deoxyribonucleosides have been limited by the inability of phosgene derivatives to form the cyclic carbonate monomers that would allow for controlled ring-opening polymerisation. CO2 insertion at 1 atm pressure into methylated thymidine 2'-deoxyribonucleoside, facilitated by organic base 1,8-diazabicyclo-[5.4.0]-undec-7-ene, affected an intramolecular SN2-like displacement of a tosyl leaving group to yield the cyclic carbonate by stereochemical inversion. Organocatalytic ring-opening polymerisation proceeded rapidly in solution resulting in high monomer conversions of 93% and number-average molecular weights, substantially greater and more controlled than via polycondensation routes. The thermodynamic parameters of the polymerisation (Delta H-p = -12.3 +/- 0.4 kJ mol(-1) and Delta S-p = -29 +/- 1.1 J mol(-1) K-1) were determined from the equilibrium monomer conversions over a temperature range of 0 to 80 degrees C and pseudo-first order kinetics demonstrated. The amorphous thymidine-based polycarbonates exhibited high glass transition temperatures of 156 degrees C and were found to be highly degradable to the constituent diol under basic aqueous conditions. Static water contact angle measurements and cell studies with MG-63 cell line indicated slightly hydrophilic and biocompatible materials, promising for tissue-engineering applications. The novel, CO2-driven approach to cyclic carbonate synthesis represents a means of expanding the scope of sugar-based monomers for tailored material properties derived from natural products.