Defined chemical transformation in Lignin, enabling to access shell-core-functionalized Lignin-colloids for selective ion binding.

本研究的目的是研究一种确定的两步化学反应，以选择性地激活木质素复杂结构网络中重要的芳香族核心结构。该反应将用于获得壳稳定和核功能化的木质素胶体，应该研究它们特异性结合复杂离子混合物中的重金属离子的能力。木质素是一种可再生资源，为可持续材料解决方案提供了巨大的潜力，因为原木质素是一种廉价的纸浆生产“废物”。木质素的使用提供了各种机会。然而，现代材料应用通常需要木质素的化学衍生化，其局限性源于结构不均匀和批次之间的强烈变化。与通常用于木质素衍生化的非选择性反应相反，该项目正在研究离散两步反应的可能性，以选择性地操纵木质素的4-羟基-3-甲氧基苯-(G)型和对羟基苯基-(H)型结构元素。G型和h型芳烃被2-碘氧基苯甲酸（IBX）以无金属的方式氧化生成邻醌。它们作为迈克尔受体与各种硫醇发生反应，可以快速而干净地转化为巯基儿茶酚。该化学方法提供了引入功能硫醇的可能性，例如含有cys的二肽和三肽，以及巯基端功能聚合物，例如mPEG-SH， cys -肽- peg偶联物或PNIPAm-SH。利用木质素网络中的扩散限制，将获得壳核木质素。功能木质素核应适应重金属离子特异性结合的需要，并通过壳独立于木质素核调节胶体稳定性。随后加入醌/巯基的木质素IBX活化不仅保留了对离子结合很重要的酚oh基团。此外，巯基儿茶酚是1,2-二羟基苯螯合配体的衍生物，可以通过巯基取代基进行功能化或微调。该项目研究了木质素的精确化学活化的潜力，以合成木质素胶体，并利用它们来从更复杂的离子混合物中获得重金属离子的离子特异性络合的基本理解。该研究利用系统的壳核木质素物质文库，研究金属离子结合、聚合物壳的照明效应、木质素核以及木质素核中实现的功能，包括针对特定重金属离子的肽基结合域。

Objective of the research proposal is to investigate a defined two-step chemical reaction to selectively activate important aromatic core structures in the complex structural network of lignin. The reaction will be utilized to access shell-stabilized and core-functionalized lignin colloids, that should be investigated on their capabilities to specifically bind heavy metal ions from complex ion mixtures.Lignins are constituting a renewable resource that offers enormous potential for sustainable material solutions, as raw lignin is an inexpensive “waste” product from paper pulp production. The use of lignin provides various opportunities. However, modern material applications often require chemical derivatization of lignin, where limitations result from the inhomogeneous structure and strong batch-to-batch variations.In contrast to rather unselective reactions that are often used for lignin derivatization, the project is investigating the possibilities of a discrete two-step reaction for the selective manipulation of both, the 4-hydroxy-3-methoxybenzene-(G)-type and p-Hydroxyphenyl-(H)-type structural elements of lignin. The G- and H-type aromatics will be oxidized by 2-iodoxybenzoic acid (IBX) in a metal-free manner to yield ortho-quinones. These react as Michael acceptors with various thiols and can be converted rapidly and cleanly to thiol-catechols.The chemistry provides the possibility of introducing functional thiols, such as Cys-containing di- and tripeptides but also thiol-end functional polymers, such as mPEG-SH, Cys-peptide-PEG conjugates or PNIPAm-SH. Exploiting the diffusion limitations in the lignin network, shell-core lignins will be accessed. The functional lignin core should be adapted to the needs of specific binding of heavy metal ions and the colloidal stability will be adjusted independently of the lignin core via the shell.The IBX activation of lignin with subsequent quinone/thiol-Michael addition not only preserves the phenolic OH-groups that are important for ion binding. Moreover, thiol-catechols are generated as derivatives of the potent 1,2-dihydroxybenzene chelate ligand, which can be functionalized or fine-tuned via the thiol substituents.The project investigates the potential of a precise chemical activation of lignin for the synthesis of lignin-colloids and their use to gain basic understanding of the ion-specific complexation of heavy metal ions from more complex ion mixtures. The investigation utilizes systematic substance libraries of shell-core lignins, to study metal-ion binding, illuminating effects of the polymer shell, the lignin core and the functionalities implemented there including peptide-based binding domains for specific heavy metal ions.