Control of Helix Sense by Composition of Chiral-Achiral Copolymers ofN-Propargylbenzamides
作者:Junichi Tabei、Masashi Shiotsuki、Takahiro Sato、Fumio Sanda、Toshio Masuda
DOI:10.1002/chem.200401009
日期:2005.6.6
did the preferential helical sense change with the copolymer composition. However, the copolymers of chiral nonbulky 2 and achiral nonbulky 3 did not change the helical sense, irrespective of the composition. The free energy differences between the plus and minus helical states, as well as the excess free energy of the helix reversal, of those chiral-achiral random copolymers were estimated by applying
N-炔丙基苯甲酰胺1-7与(nbd)Rh(+)[η(6)-C(6)H(5)B(-)(C(6H)(5))(3)]聚合中等分子量(M(n)= 26,000-51,000)的高收率聚合物。(1)H NMR光谱表明该聚合物具有相当立体规则的结构(81-88%顺式)。光学活性聚合物poly(1)和poly(2)已通过其强烈的CD信号和较大的旋光度证明,当在CHCl(3)或甲苯中加热时,会采用稳定的螺旋构象,且具有单手的螺线感。 。棉花效应的迹象可通过改变手性大分子1和非手性非本体3或手性非大分子2和非手性本体7的共聚物中的含量来控制。非手性单体与1的共聚中的侧基越小。优先螺旋感随共聚物组成的变化越容易。然而,手性非本体2和非手性非本体3的共聚物不改变螺旋感,而与组成无关。这些手性-非手性无规共聚物的正和负螺旋状态之间的自由能差以及螺旋反转的过量自由能通过应用改良的伊辛模型进行估算。