Dynamic Covalent Assembly of Abiotic, Information-bearing Oligomers

Dynamic covalent chemistry;Peptoid;Imine;Chemical Engineering;Engineering;Chemical Engineering

Wei, TaoLahann, Joerg ;

University of Michigan

关键词: Dynamic covalent chemistry;    Peptoid;    Imine;    Chemical Engineering;    Engineering;    Chemical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/140819/taowei_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

A long-standing challenge in the field of self-assembly is creating nanostructures that rival the complexity of their biological counterparts. One example is the DNA double helix, which has been used to construct complex, multi-dimensional structures triggered by the self-assembly instructions encoded in DNA sequences. However, due to the weakness of hydrogen bonding in the DNA structures, these assemblies are fragile and susceptible to thermal and mechanical degradation. To address these deficiencies, dynamic covalent self-assembly of sequence-specific peptoids is used to create chemically and thermomechanically robust nanostructures. In particular, the dynamic covalent assembly used relies on the reversible amine/aldehyde reaction to generate imine linkages.This dissertation details the design and synthesis of sequence-specific peptoids that contain dynamic covalent functional groups (amines and aldehydes) that self-assemble into molecular ladders through imine condensation and exchange reactions catalyzed by scandium(III) triflate. Furthermore, three potential mechanisms of ladder formation are proposed here, including a ;;molecular zipper’, a ;;molecular hand-shake line’ and ;;toehold displacement’. MALDI mass spectrometry and distance measurements using Förster resonance energy transfer (FRET) were employed to determine the hybridization mechanism, indicating that two complementary strands initially interact and bind by rapidly ;;zipping-up’ at any point generating molecular ladders with an arbitrary number of rungs, followed by slowly shuffling through a ;;molecular hand-shake line’ until these ladders come into registry. In addition, small precursor peptoids of mismatched numbers of complementary functional groups are used to self-assemble into large structures through Vernier-templating. Strand exchange experiments based on transimination and imine metathesis are designed to determine the rate-limiting step for Vernier-templated assembly. Finally, this dissertation discusses the development of an elegant approach for the dynamic covalent assembly of oliogmeric species bearing both amine and aldehyde functional groups by employing scandium(III) triflate as a dual role catalyst, effecting both in situ ethylene acetal deprotection and imine exchange reactions. Combined, these findings open up possibilities to design and construct robust, complex nanostructures based on the self-assembly of sequence-specific, dynamic covalent oligomers with potential applications from information storage to high precision nano-filtration membrane to smart matrix grids for energy harvesting.