Protection‐Group‐Free Synthesis of Sequence‐Defined Macromolecules via Precision λ‐Orthogonal Photochemistry

Abstract

An advanced light-induced avenue to monodisperse sequence-defined linear macromolecules via au nique photochemical protocol is presented that does not require any protection-group chemistry.S tarting from as ymmetrical core unit, precision macromolecules with molecular weights up to 6257.10 gmol À1 are obtained via at wo-monomer system: am onomer unit carrying ap yrene functionalized visible light responsive tetrazole and ap hoto-caged UV responsive diene, enabling an iterative approach for chain growth;and amonomer unit equipped with acarboxylic acid and afumarate.Both light-induced chain growth reactions are carried out in a lorthogonal fashion, exciting the respective photosensitive group selectively and thus avoiding protecting chemistry. Characterization of each sequence-defined chain (size-exclusion chromatography (SEC), high-resolution electrospray ionization mass spectrometry (ESI-MS), and NMR spectroscopy), confirms the precision nature of the macromolecules.

Dual sequence definition increases the data storage capacity of sequence-defined macromolecules

“…Such macromolecules with a distinct order of the monomer units and a defined length are termed "uniform" molecules according to IUPAC 1 . Many routes towards sequence-defined structures have been developed over the last years, aiming for an increasing degree of control and precision [2][3][4][5][6][7][8][9][10][11][12][13][14][15] . The sequence-defined structures represent a new class of molecules in the polymer area, combining the features of classic polymers that are consisting of many repeating units, thus leading to their characteristic properties, with the ones of organic molecules, being uniform in size as well as constitution and topology.…”

High-density information storage in an absolutely defined aperiodic sequence of monodisperse copolyester

“…The solid-phase synthesis has been a method to synthesize polymers with defined aperiodic sequences [9][10][11][12] . Although sequence-defined polymers with more than 100 repeating units have been synthesized 13,14 , synthesis has largely been limited to sequence-defined oligomers with a limited number of repeating units due to the difficulties associated with the repeated step-bystep addition of individual monomers to achieve high molecular weights [15][16][17][18][19][20][21][22][23][24][25][26] . The iterative convergent method has been widely adopted for the synthesis of dendritic and linear macromolecules with precisely defined chemical structures [27][28][29][30] .…”

Access to Photoreactive Core‐Shell Nanomaterials by Photoinitiated Polymerization‐Induced Self‐Assembly

“…The available set of photoinduced reactions constitutes an efficient, finely controllable, and environmentally friendly toolbox in chemistry for applications as varied as light‐induced deprotection reactions in organic synthesis, photopolymerization in dentistry, 3D printing, and photocatalysis . Importantly, the use of so‐called λ‐orthogonal reactions, which can be triggered independently by suitable choice of reaction partners and irradiation wavelengths, allows complex reaction schemes and new functions in materials The incorporation of photoreactive groups in polymeric materials enables a great variety of possibilities, e. g ., collapse of single‐chain nanoparticles, block copolymer synthesis by classic free‐radical polymerization, and crosslinking reactions . The usual mild reaction conditions also enable bioconjugation onto materials such as nanoparticles (NPs) .…”