کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5181231 1380955 2014 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Polymeric molecular shuttles: Polypseudorotaxanes & polyrotaxanes based on viologen (paraquat) urethane backbones & bis(p-phenylene)-34-crown-10
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Polymeric molecular shuttles: Polypseudorotaxanes & polyrotaxanes based on viologen (paraquat) urethane backbones & bis(p-phenylene)-34-crown-10
چکیده انگلیسی

Reaction of di(p-isocyanatophenyl)methane (MDI, 4) with N,N′-di(2-hydroxyethyl)- (1b) or N,N′-di[2-(2′-hydroxyethoxy)ethyl]-4,4′-bipyridinium di(hexafluorophosphate) (1e) and other diols [oligo(ethylene glycol)s and poly(tetramethylene oxide)s] in the presence of bis(p-phenylene)-34-crown-10 (2) afforded polyurethane (pseudo)rotaxanes as statistical (7P or 7R) and segmented analogs 10P (P = pseudorotaxane, R = rotaxane). In 7R a bulky alcohol was incorporated at the chain ends and in 13R a bulky diol as in-chain units to form polyrotaxanes and preclude the possibility of dethreading. The crown ether 2 in 10P and 13R was shown by 1H NMR spectroscopy to be shuttling between the viologen (paraquat) and urethane sites; in DMSO the crown ether prefers the urethane site, probably because of H-bonding with the N-H moieties and complexation of the pyridinium site by the dipolar solvent, while in acetone at low temperatures the viologen site is preferred by the crown ether, with ΔH = −6.91 kcal/mol and ΔS = −22.9 eu for 13R.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 55, Issue 15, 25 June 2014, Pages 3202-3211
نویسندگان
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