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(a) Molecular structures of rotaxanes 1 and 2, luminophore 3, and dumbbell 4. (b) Synthesis and molecular structure of the mechanophore-containing polyurethane 1-PU. This polymer was prepared from poly(tetrahydrofuran) (PTHF), 4,4′-methylenebis(phenylisocyanate) (MDI), rotaxane 1, and 1,4-butanediol (BDO) in a polymerization catalyzed by dibutyltin dilaurate (DBTDL). The x:y and x:z ratios were determined by 1H NMR spectroscopy and the fraction of 1 in the monomer feed.
