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Click‐Functionalization of a Poly(Tetrazine‐co‐Fluorene)‐Conjugated Polymer with a Series of trans ‐Cyclooctene Derivatives
Author(s) -
Kardelis Vladimir,
Denk Maria M.,
Adronov Alex
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202010795
Subject(s) - tetrazine , polymer chemistry , cyclooctene , chemistry , fluorene , polymer , polymerization , copolymer , romp , conjugated system , ethylene glycol , side chain , photochemistry , organic chemistry , metathesis , catalysis
Abstract A soluble poly(tetrazine) polymer was prepared via Suzuki polycondensation of 3,6‐bis(5‐bromofuran‐2‐yl)‐1,2,4,5‐tetrazine and a fluorene diboronate derivative. It can undergo efficient and quantitative post‐polymerization inverse‐electron‐demand Diels–Alder click reactions with a variety of trans ‐cyclooctene (TCO) derivatives. The resulting polymers were oxidized to convert dihydropyridazine rings into pyridazines. The absorption spectra of the product polymers, both before and after oxidation, showed hypsochromic shifts that correlated with steric hindrance of the appended side chains. They also exhibited a significantly enhanced fluorescence intensity relative to the original poly(tetrazine). While gel‐permeation chromatography indicated that the product polymers exhibited longer retention times, NMR end‐group analysis showed that the polymers retained relatively constant degrees of polymerization. Graft copolymers were easily prepared via reaction with TCO‐functionalized poly(ethylene glycol) chains and a cross‐linked foam was produced by reacting the poly(tetrazine) with a bis‐TCO crosslinker.