Solvent Clathrate Driven Dynamic Stereomutation of a Supramolecular Polymer with Molecular Pockets
作者:Chidambar Kulkarni、Peter A. Korevaar、Karteek K. Bejagam、Anja R. A. Palmans、E. W. Meijer、Subi J. George
DOI:10.1021/jacs.7b07639
日期:2017.10.4
understand the phenomena at a molecular level are scarce. Here we present a unique example of helix reversal (stereomutation) under thermodynamic control in the self-assembly of a coronenebisimide that has a 3,5-dialkoxy substitution on the imide phenyl groups (CBI-35CH), leading to "molecular pockets" in the assembly. The stereomutation was observed only if the CBI monomer possesses molecular pockets.
Mesoscopic helical architectures via self-assembly of porphyrin-based discotic systems
作者:Sonia Vela、José Augusto Berrocal、Carmen Atienza、E. W. Meijer、Nazario Martín
DOI:10.1039/c7cc01670k
日期:——
Mesoscopic super-helices with preferred helicity have been serendipitously formed via the self-assembly of electroactive extended core discotic molecules.
通过电活性扩展核心圆盘分子的自组装,偶然形成了具有优选螺旋性的中等尺度超螺旋体。
Distance Matters: Biasing Mechanism, Transfer of Asymmetry, and Stereomutation in N-Annulated Perylene Bisimide Supramolecular Polymers
by two methylenes and an ester group, form J-type supramolecularpolymers in a cooperative manner but exhibit negligible chiroptical properties. The lack of clear helicity, due to the staircase arrangement of the self-assembling units in the aggregate, justifies these features. In contrast, attaching the peripheral groups directly to the N-annulated PBI core drastically changes the self-assembling properties
报道了两个系列的N-环化苝双酰亚胺(PBI)化合物1和2的合成,并通过一整套光谱测量和理论计算彻底研究了它们的自组装特征。该研究证实了PBI核心与外围基团之间的距离对手性光学性质和超分子聚合机制的巨大影响。化合物1的外围基团通过两个亚甲基和一个酯基与中心PBI核心分开,以协同方式形成J型超分子聚合物,但表现出可忽略不计的手性光学性质。由于聚合体中自组装单元的阶梯排列,缺乏明显的螺旋性,证明了这些特征的合理性。相比之下,将外围基团直接连接到 N 环形 PBI 核心会极大地改变化合物2的自组装特性,从而按照等阻机制形成 H 型聚集体。这些 H 型聚集体表现出强烈的聚集引起的猝灭 (ACQ) 效应,从而导致非发射聚集体。手性( S ) -2和( R )-2经历了不对称性的有效转移,分别提供 P型和 M 型聚集体,尽管在多数规则或“军士和士兵”实验中没有实现不对称性的放大。观察到手性( S )-2和(
Synthesis and structure of poly(phenyl isocyanate)s bearing an optically active alkoxyl group
Novel opticallyactive phenyl isocyanate derivatives (1–6) bearing an (R)-sec-butoxy, (S)-2-methylbutoxy or (S)-3,7-dimethyloctyloxy group at the meta or para position on the phenyl ring were prepared and polymerized with an anionic initiator in tetrahydrofuran (THF). The resulting polymers from 1, 2, 4 and 6 showed much greater specific rotation than that of the corresponding monomers and an intense
Total Synthesis of All Eight Stereoisomers of ?-Tocopheryl Acetate. Determination of their diastereoisomeric and enantiomeric purity by gas chromatography
作者:Noal Cohen、Clifford G. Scott、Christian Neukom、Rocco J. Lopresti、Giuseppe Weber、Gabriel Saucy
DOI:10.1002/hlca.19810640422
日期:1981.6.10
Alleightstereoisomers of α-tocopheryl acetate have been synthesized in a state of high chemical and stereoisomeric purity. Key chiral side-chain intermediates were prepared from (+)-(S)-3-hydroxy-2-methylpropanoic acid. New routes to (2R, 4′ RS, 8′ RS)-α-tocopheryl acetate, a mixture of four diastereoisomers, were also developed. A sensitive gas chromatographic method was developed to determine the