Engineering Digital Polymer Based on Thiol-Maleimide Michael Coupling Toward Effective Writing and Reading
Digital polymer as promising molecule-level storage media has arouse more and more interests. The application of digital polymer strongly relies on efficient message writing and reading. Herein, we reported the rational design of digital polymer based on thiol-maleimide Michael coupling. Bromine was used as the precursor of thiol group via the thiourea/bromine nucleophilic substitution. This chemistry enabled efficient writing with excellent group tolerance and structural diversity. Importantly, the terminal bromine acting as the isotope tag enabled the efficient reading by tandem mass spectrometry (MS/MS) sequencing. Moreover, to produce a more predictable tandem MS-induced fragmentation pattern, the computer simulation of the bond dissociation energy (BDE) was used. It was found that when the sulfur was oxidized to sulfoxide, the carbon-sulfur bond neighboring the succinimide group has much lower BDE, ~32.2 kcal/mol, allowing the selective chain cleavage during MS/MS sequencing. The MS/MS sequencing of the sulfoxide succinimide-linked digital polymer enabled efficient reading by creating an easily readable and predictable MS fragmentation. The engineered digital polymers were endowed with both efficient writing and reading, which advanced the research and application of digital polymers.