Supramolecular Copolymerization by Sequence Reorganization of a Supramolecular Homopolymer.

The homopolymeric sequence formed by the head-to-head association of tetrakisporphyrin 1 is completely dissociated by the competitive association of the ditopic guest G2, resulting in the supramolecular copolymer poly-1⋅G2 with an alternatingly repeating host-guest sequence. The 1:1 stoichiometry of 1 and G2 is confirmed by a Job plot using UV/Vis titration and diffusion-ordered NMR spectroscopy (DOSY). The solution viscometry for poly-1 and poly-1⋅G2 suggests that the supramolecular chain of poly-1 behaves like a rod, whereas the supramolecular copolymer chain of poly-1⋅G2 behaves like a swelled fat chain, which is entangled in the semi-dilute regime. Atomic force microscopy shows that the supramolecular polymer poly-1⋅G2 is highly oriented through the interdigitation of the long alkyl chains.