| |
[摘要]：Supramol. substitution reactions between hydrazide-based oligomers 1a-c and 2a-c were systematically investigated. Each oligomer existed as hydrogen-bonding mediated mol. duplex strands or a polymeric zipper structure in apolar solvents. But when another oligomer with complementary hydrogen bonding sites was added, a heterodimer structure formed due to supramol. substitution reaction driven by the formation of more hydrogen bonds, which was evidenced by NMR expts., sometimes gel-sol transition. When a nonsym. oligomer and a sym. oligomer were involved, complexation-induced nonsymmetry was obsd. When two nonsym. oligomers were involved, two hydrogen-bonded isomers were obsd. in soln. Variable-temp. 1H NMR expts. further revealed unique dynamic behavior for the individual oligomer and the complexes. When diacetyl-terminated oligomer 1c was involved, slides perpendicular to hydrogen bonds between two constituent mols. were obsd., which led to complicated 1H NMR spectra at lower temp.; otherwise, high selectivity was obtained. Combined with the results we reported previously, a detailed picture of the structure-property relationship for our hydrazide-based oligomers was depicted, which would provide guidelines for the design of hydrazide-based fine-tuning functional materials. |
|
