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

Novel 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-gamma-benzyl ester N'-propargylamide] were synthesized and polymerized with (nbd)Rh+[eta(6)-C6H5B-(C6H5)(3)] (nbd = norbornadiene) as a catalyst to obtain the corresponding polymers with moderate molecular weights in high yields. Polarimetry, circular dichroism, and ultravioletvisible spectroscopy studies revealed that both poly[N-(9-carbazolyl)ethyloxycarbonyl-L-alanine N'-propargylamide] and poly[N-(9-carbazolyl)ethyloxycarbonyl-L-glutamic acid-gamma-benzyl ester IT-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-gamma-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-gamma-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. (c) 2006 Wiley Periodicals, Inc.