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Synthesis and Helical Structure of Poly(1‐methylpropargyl ester)s with Various Side Chains
Author(s) -
Suzuki Yuji,
Shiotsuki Masashi,
Sanda Fumio,
Masuda Toshio
Publication year - 2008
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.200800131
Subject(s) - dihedral angle , polymer , norbornadiene , side chain , polymerization , copolymer , polymer chemistry , chemistry , helix (gastropod) , materials science , crystallography , catalysis , molecule , organic chemistry , hydrogen bond , ecology , snail , biology
Optically active 1‐methylpropargyl esters bearing various substituents were polymerized with [(nbd)Rh] + [η 6 ‐C 6 H 5 B(C 6 H 5 ) 3 ] − (nbd=norbornadiene) as a catalyst to afford the corresponding poly(1‐methylpropargyl ester)s with moderate molecular weights in good yields. The polymers have a cis ‐stereoregular structure, which was determined by 1 H NMR spectroscopy. Large optical rotations and clear CD signals demonstrated that all these polymers take on a helical structure with a predominantly one‐handed screw sense. The polymers exhibited large viscosity indices in the range 1.14–1.75. Chiral amplification was observed in R / S copolymerization. Conformational analysis revealed that the polymers form a tightly twisted helical structure with a dihedral angle of 70° at the single bond of the main chain.