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Abstract
Nature uses sequence-defined (having a precise sequence of units) monodisperse (same molecularweight) polymers for data storage and transfer (DNA, RNA), for controlling properties and
structure (proteins), for the efficient catalysis of various reactions (enzymes), and many more.
However, these bio-macromolecules have limited stability and lack chemical and structural
diversity. Current methods for synthesizing sequence-defined monodisperse polymers are based
on solid support to facilitate the removal of by-products and excess reagents at each step. This
method limits the amount of polymer production to milligram quantities. To synthesize the larger
quantities of sequence-defined polymers, we have developed an ACB-type trifunctional monomer
based on photo-SPAAC ligation. A is photo-caged cyclooctyne; B is azide; and C is a moiety
allowing the attachment of various functionalities (e.g., dye, catalysts, enzymes, etc.). Photoactivation
of the growing chain terminus allows for the attachment of the next monomer and this
monomer has been shown to quench itself, preventing the formation of mismatched sequences.
We have demonstrated the purification-free synthesis of two pentamers sequences.