Sequence-controlled supramolecular terpolymerization directed by specific molecular recognitions

Abstract

Nature precisely manipulates primary monomer sequences in biopolymers. In synthetic polymer sequences, this precision has been limited because of the lack of polymerization techniques for conventional polymer synthesis. Engineering the primary monomer sequence of a polymer main chain represents a considerable challenge in polymer science. Here, we report the development of sequence-controlled supramolecular terpolymerization via a self-sorting behavior among three sets of monomers possessing mismatched host-guest pairs. Complementary biscalix[5]arene-C₆₀, bisporphyrin-trinitrofluorenone (TNF), and Hamilton's bis(acetamidopyridinyl)isophthalamide-barbiturate hydrogen-bonding host-guest complexes are separately incorporated into heteroditopic monomers that then generate an ABC sequence-controlled supramolecular terpolymer. The polymeric nature of the supramolecular terpolymer is confirmed in both solution and solid states. Our synthetic methodology may pave an avenue for constructing polymers with tailored sequences that are associated with advanced functions.Nature can precisely control monomer sequences in biopolymers, but this is somewhat problematic in the formation of synthetic polymers. Here the authors show sequence-controlled supramolecular terpolymerization via self-sorting behavior among three sets of monomers possessing mismatched host-guest pairs.

Fig. 1

Supramolecular terpolymerization. a Schematic representation of the supramolecular terpolymerization of three components A, B, and C via self-sorting assembly or random assembly. b Host–guest structures of the biscalix[5]arene-C₆₀ complex, bisporphyrin-TNF complex, and Hamilton’s hydrogen-bonding complex. c Structures of the three heteroditopic monomers 1, 2, and 3 possessing mismatched host–guest pairs. d Sequence-controlled supramolecular polymerization of three sets of heteroditopic monomers via a self-sorting

Fig. 2

Self-sorting behaviors in supramolecular terpolymerization. The ¹H NMR spectra of a 1, b 2, c 3, d a mixture of 1 and 2, e a mixture of 2 and 3, f a mixture of 1 and 3, and g a mixture of 1, 2, and 3 in chloroform-d ₁. h Job plots for the 1•2, 2•3, and 1•3 heterodimeric complexes. i ESI-MS spectrum of a mixture of 1, 2, and 3. Observed isotope distributions are highlighted in blue, and the calculated distributions are highlighted in red

Fig. 3

Properties and morphologies of supramolecular terpolymer [1–2–3]_n. a Diffusion coefficients (D) in chloroform-d ₁. b Viscosities (η) in chloroform. c SEM image of supramolecular terpolymer. The scale bar denotes 40 μm. d AFM image (200 nm × 200 nm) of a spin-coated film