Easily readable palindromic sequence-defined polymers built by cascade thiol-maleimide Michael couplings

Abstract

Palindromic sequence-induced specific and genetic functions widely exist in biological systems. Nevertheless, the study of synthetic palindromic sequence-defined polymers has received scarce attention due to the challenge of efficient synthesis. Herein, we demonstrated cascade thiol-maleimide Michael couplings (CTMMC) as an efficient chemistry to access palindromic sequences. Taking bromomaleimide as the synthon, the CTMMC enabled the construction of an array of palindromic sequences at an accelerated growth rate via an iterative exponential growth strategy. Moreover, owing to the synergetic cleavages of two C–S bonds located in dithiosuccinimide linkages, the palindromic sequences were easily readable (i.e., decipherable) by tandem mass spectrometry. The CTMMC chemistry endowed structural versatility and diversity to the palindromic sequences, thereby uncovering many potential applications, such as anti-counterfeiting labeling and item identification like artificial “DNA”.