Controlled helical orientation of carbazole in amino acid derived poly(N‐propargylamide)s

Abstract

AbstractNovel L‐alanine and L‐glutamic acid derivatized, carbazole‐containing N‐propargylamides [N‐(9‐carbazolyl)ethyloxycarbonyl‐L‐alanine N′‐propargylamide and N‐(9‐carbazolyl)ethyloxycarbonyl‐L‐glutamic acid‐γ‐benzyl ester N′‐propargylamide] were synthesized and polymerized with (nbd)Rh+[η6‐C6H5B−(C6H5)3] (nbd = norbornadiene) as a catalyst to obtain the corresponding polymers with moderate molecular weights in high yields. Polarimetry, circular dichroism, and ultraviolet–visible spectroscopy studies revealed that both poly[N‐(9‐carbazolyl)ethyloxycarbonyl‐L‐alanine N′‐propargylamide] and poly[N‐(9‐carbazolyl)ethyloxycarbonyl‐L‐glutamic acid‐γ‐benzyl ester N′‐propargylamide] took a helical structure with a predominantly one‐handed screw sense in tetrahydrofuran, CHCl3, and CH2Cl2. The helix content of poly[N‐(9‐carbazolyl)ethyloxycarbonyl‐L‐alanine N′‐propargylamide] could be tuned by heat or the addition of a protic solvent, and the helical sense of poly[N‐(9‐carbazolyl) ethyloxycarbonyl‐L‐glutamic acid‐γ‐benzyl ester N′‐propargylamide] was inverted by heat in CHCl3 or in mixtures of tetrahydrofuran and CH2Cl2. Poly[N‐(9‐carbazolyl) ethyloxycarbonyl‐L‐alanine N′‐propargylamide] and poly[N‐(9‐carbazolyl)ethyloxycarbonyl‐L‐glutamic acid‐γ‐benzyl ester N′‐propargylamide] also took a helical structure in film states. They showed small fluorescence in comparison with the monomers and redox activity based on carbazole. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 253–261, 2007