Using non-covalent interactions to direct regioselective 2+2 photocycloaddition within a macrocyclic cavitand
作者:Nga Nguyen、Aspen Rae Clements、Mahesh Pattabiraman
DOI:10.1039/c5nj02376a
日期:——
completely from a head-to-head dimer to a head-to-tail dimer. The reactions were also stereoselective in most cases. Stoichiometry experiments were performed to explore relative stabilities of the complexes, which indicate that the ternary complex is more stable than others. Selectivity in the photocycloaddition reaction was also applied retrospectively to deduce intermolecular orientations. Time-dependent
Templating Photodimerization of <i>trans</i>-Cinnamic Acid Esters with a Water-Soluble Pd Nanocage
作者:S. Karthikeyan、V. Ramamurthy
DOI:10.1021/jo0617722
日期:2007.1.1
trans-cinnamic acid methyl esters in water. Irradiation of the host−guest complexes of trans-cinnamic acid methyl esters with the Pd nanocage resulted in selective formation of a syn head−head dimer in addition to the corresponding cis isomer. These results suggest that the guest molecules are preoriented in a selective fashion with the hydrophilic ester group facing water and the hydrophobic aryl group
Lewis acid catalysis of photochemical reactions. 7. Photodimerization and cross-cycloaddition of cinnamic esters
作者:Frederick D. Lewis、Suzanne L. Quillen、Paul D. Hale、Joe D. Oxman
DOI:10.1021/ja00212a039
日期:1988.2
cases the Lewisacid complexes dimerize more efficiently and stereoselectively than the free esters. Photodimerization and cross-cycloaddition of methyl cinnamate in dilute solution is also catalyzed by Lewisacids. The mechanism of these reactions involves electronic excitation of a ground-state ester (dimerization) or simple olefin (cross cycloaddition). The catalytic effect of Lewisacids is attributed
were observed suggesting the formation of a non-centrosymmetric photodimer. Removing hydrogen bonds from the system by esterfication of alpha-truxillic acid yield a centrosymmetric photodimer. Careful analysis of the obtained products via solid-state NMR clearly showed that the observed peak splittings in the 13C-CPMAS spectra did not originate from packing effects but rather result from asymmetric hydrogen
13C-CPMAS和其他固态核磁共振方法已被应用于监测反式肉桂酸衍生物的固态反应,这是先前通过X射线衍射、原子力显微镜和原子力显微镜研究的拓扑化学领域的先驱和模型化合物。振动光谱。单晶 X 射线分析光照射的 α-反式肉桂酸,其中单体以头对尾的方式排列,揭示了中心对称的 alpha-truxillic 酸光二聚体的形成。然而,对于中心对称二聚体,除了其他芳族碳信号之外,预计会有两个环丁烷碳信号和一个羰基碳信号。相反,观察到四个环丁烷和两个羰基碳信号,表明形成了非中心对称的光二聚体。通过 α-树胶酸的酯化从系统中去除氢键产生中心对称的光二聚体。通过固态 NMR 对所得产物的仔细分析清楚地表明,在 13C-CPMAS 光谱中观察到的峰分裂并非源于堆积效应,而是由不对称氢键扭曲局部对称性造成的。这种相当动态的氢键的进一步证据源于高温 X 射线数据,表明只有在相似温度下 X 射线分析和固态 NMR
Amphiphilic diblock copolymers, poly(ethylene glycol)-block-poly(acrylate), bearing truxillic acid derivatives at the junction point between the two blocks are described. The truxillic acid junction can be selectively cut by UV light, leading to a disassembly of the nano-objects made by self-assembly of the amphiphilic copolymers in water.