PREPARATION OF POLYMERS WITH SECONDARY STRUCTURES SPONTANEOUSLY REGULATED BY HYDROGEN BONDING AMONG SIDE CHAINS AND THEIR APPLICATION AS MOLECULAR DEVICES

采用芳香胺对等规聚甲基丙烯酸的侧链羧基进行酰胺化，制备了主链和侧链结构均有调控的聚甲基丙烯酰胺。随后研究了侧链酰胺基团之间的氢键和侧链发色团的取向。具有侧链(S) -1-苯基乙基的等规聚甲基丙烯酰胺比具有侧链(S) -1-（1-萘基）乙基和其他侧链基团的等规聚甲基丙烯酰胺更广泛地形成分子内氢键，前者在稳定全氢键结构方面表现出充分的位阻效应。分子力学计算表明，具有s型侧链基团的等规聚甲基丙烯酰胺具有右手5_2螺旋。发现当聚甲基丙烯酰胺采用全氢键结构时，侧链间激发能传递效率显著提高。发现这些聚合物在薄膜中形成片层结构。当(s) -1-（1-萘基）乙基和其他具有足够空间位阻的基团在侧链中引入时，聚l -谷氨酰胺具有沿螺旋主链取向的发色团的侧链二级结构。荧光猝灭实验表明，激发能通过这些定向发色团有效地传递。由这些聚合物制备的薄膜的圆二向色光谱表明，有三种不同发色团取向的侧链结构。分子力学计算表明，侧链结构中存在几种稳定或准稳定的侧链结构，其中有一种侧链与侧链之间存在氢键，这与红外观察结果一致，侧链酰胺基团之间存在广泛的氢键。研究还表明，这种氢键使主链构象偏离了α -螺旋构象。目前正在尝试将各向异性引入这些薄膜。如上所述，等规聚（甲基丙烯酰胺）s和聚（l -谷氨酰胺）s作为分子器件的用途现已确定。通过在侧基中引入芘和二茂铁等发色团，进一步研究了它们的激发能输运和电荷输运功能。少

Poly (methacrylamide) s with regulated primary structures, i.e., main-chain tacticity and side-chain structure, were prepared by amidation of the side-chain carboxyl groups of isotactic poly (methacrylic acid) with aromatic amines. Hydrogen bonding among the side-chain amide groups and side-chain chromophore orientation were subsequently examined. Isotactic poly (methacrylamide) having (S) -1-phenylethyl groups in the side chains was found to form intramolecular hydrogen bonding more extensively than those having (S) -1- (1-naphthyl) ethyl and other side-chain groups, showing adequate steric effects in the former in stabilizing the fully-hydrogen-bonded structure. Molecular mechanics calculations suggest that the isotactic poly (methacrylamide) s with side-chain groups of S-configuration assume right-handed 5_2 helices. The efficiency of excitation energy transport among the side chains was found to improve markedly when the poly (methacrylamide) s assume fully-hydrogen-bonded structur … More es. These polymers were found to form lamellar structures in films.Poly (L-glutamine) s were found to assume side-chain secondary structures with chromophores oriented along the helical main chain when (S) -1- (1-naphthyl) ethyl groups and others having adequate steric hindrances are introduced in the side chains. Fluorescence quenching experiments showed that excitation energy is transported efficiently through these oriented chromophores. Circular dichroic spectra of films prepared from these polymers showed that there are three types of side-chain structures with varying chromophore orientation. Molecular mechanics calculations suggest there are several stable or quasi-stable side-chain structures, and in one of them hydrogen bonding occurs between the main chain and the side chain in accord with the IR observation that side-chain amide groups are extensively hydrogen-bonded. It is also suggested that such hydrogen bonds cause deviation of the main-chain conformation from alpha-helix. Introduction of anisotropy to these films are now being attempted.As described above, the usefulness of isotactic poly (methacrylamide) s and poly (L-glutamine) s as molecular devices is now established. Their excitation energy transport and charge transport functions are now being investigated further by introducing such chromophores as pyrene and ferrocene in the side groups. Less