Polymeric Photoacids Based on Naphthols-Design Criteria, Photostability, and Light-Mediated Release.,Chemistry - A European Journal

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Polymeric Photoacids Based on Naphthols-Design Criteria, Photostability, and Light-Mediated Release.
Chemistry - A European Journal ( IF 3.9 ) Pub Date : 2020-01-21 , DOI: 10.1002/chem.201903819
Felix Wendler _{1,

2} , Maria Sittig _{2,

3,

4} , Jessica C Tom _{1,

2} , Benjamin Dietzek _{2,

3,

4} , Felix H Schacher _{1,

2}

Affiliation

The implementation of photoswitches within polymers offers an exciting toolbox in the design of light-responsive materials as irradiation can be controlled both spatially and temporally. Herein, we introduce a range of water-soluble copolymers featuring naphthol-based chromophores as photoacids in the side chain. With that, the resulting materials experience a drastic increase in acidity upon stimulation with UV light and we systematically studied how structure and distance of the photoacid from the copolymer backbone determines polymerizability, photo-response, and photostability. Briefly, we used RAFT (reversible addition-fragmentation chain transfer) polymerization to prepare copolymers consisting of nona(ethylene glycol) methyl ether methacrylate (MEO9 MA) as water-soluble comonomer in combination with six different 1-naphthol-based ("N") monomers. Thereby, we distinguish between methacrylates (NMA, NOeMA), methacrylamides (NMAm, NOeMAm), vinyl naphthol (VN), and post-polymerization modification based on [(1-hydroxynaphthalen-2-amido)ethyl]amine (NOeMAm, NAmeMAm). These P(MEO9 MAx -co-"N"y ) copolymers typically feature a 4:1 MEO9 MA to "N" ratio and molar masses in the range of 10 kg mol-1 . After synthesis and characterization by using NMR spectroscopy and size exclusion chromatography (SEC), we investigated how potential photo-cleavage or photo-degradation during irradiation depends on the type and distance of the linker to the copolymeric backbone and whether reversible excited state proton transfer (ESPT) occurs under these conditions. In our opinion, such materials will be strong assets as light-mediated proton sources in nanostructured environments, for example, for the site-specific creation of proton gradients. We therefore exemplarily incorporated NMA into an amphiphilic block copolymer and could demonstrate the light-mediated release of Nile red from micelles formed in water as selective solvent.

中文翻译：

基于萘酚的聚合光酸设计标准、光稳定性和光介导释放。

由于可以在空间和时间上控制照射，因此在聚合物中实现光开关为光响应材料的设计提供了令人兴奋的工具箱。在此，我们介绍了一系列水溶性共聚物，其特征是萘酚基发色团作为侧链中的光酸。由此，所得材料在紫外线刺激下酸度急剧增加，我们系统地研究了光酸的结构和与共聚物主链的距离如何决定聚合性、光响应和光稳定性。简而言之，我们使用RAFT（可逆加成-断裂链转移）聚合制备了由九(乙二醇)甲醚甲基丙烯酸酯(MEO9 MA)作为水溶性共聚单体与六种不同的1-萘酚基(“N”)组成的共聚物。）单体。由此，我们区分了甲基丙烯酸酯（NMA、NOeMA）、甲基丙烯酰胺（NMAm、NOeMAm）、乙烯基萘酚（VN）以及基于[（1-羟基萘-2-酰胺基）乙基]胺的后聚合改性（NOeMAm、NAmeMAm）。这些 P(MEO9 MAx -co-“N”y ) 共聚物通常具有 4:1 MEO9 MA 与“N”之比，摩尔质量在 10 kg mol-1 范围内。使用核磁共振波谱和尺寸排阻色谱 (SEC) 进行合成和表征后，我们研究了辐照期间潜在的光裂解或光降解如何取决于连接体与共聚物主链的类型和距离，以及是否可逆激发态质子转移（ ESPT）在这些条件下发生。我们认为，此类材料将成为纳米结构环境中光介导质子源的强大资产，例如，用于特定位置创建质子梯度。因此，我们示例性地将 NMA 掺入两亲性嵌段共聚物中，并且可以证明尼罗红从作为选择性溶剂的水中形成的胶束中光介导的释放。

更新日期：2020-01-22

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