Stable Helical Polyguanidines:  Poly{ N -(1-anthryl)- N ‘ -[( R )- and/or ( S )-3,7-dimethyloctyl]guanidines}

作者：Hong-Zhi Tang, Yujie Lu, Gonglu Tian, Michael D. Capracotta, Bruce M. Novak · 发表于：Journal of the American Chemical Society · 年份：2004 · DOI：10.1021/ja049937g · 被引用次数：64 · 研究领域：Synthesis and Properties of Aromatic Compounds、Organoboron and organosilicon chemistry、Supramolecular Chemistry and Complexes

Using chiral catalysts of (R)- and/or (S)-BINOL-Ti, the asymmetrical polymerization of achiral monomer, N-(1-anthryl)-N'-n-octadecylcarbodiimide, yielded soluble nonregioregular polyguanidines of Poly-R1 and Poly-S1. A racemization process occurred when the toluene solution of Poly-R1 was annealed at elevated temperatures (70-80 degrees C). Kinetic studies reveal this to be a slow process with an activation energy of ca. 36 kcal/mol. On the other hand, using titanium(IV) trifluoroethoxide catalyst, the polymerization of N-(1-anthryl)-N'-[(R)- and/or (S)-3,7-dimethyloctyl]carbodiimides afforded highly regioregular polyguanidines of Poly-R2 and Poly-S2. These polymers adopt stable helices in various solvents and elevated temperatures, whose kinetically controlled conformations and thermodynamically controlled conformations are essentially the same.