containing amide groups at imide positions are reported. The synergetic effect of intermolecular hydrogen bonding among the amide functionalities and pi-pi stacking between the PBI units directs the formation of the self-assembled structure in solution, which beyond a certain concentration results in gelation. Effects of different peripheral alkyl substituents on the self-assembly were studied by solvent-
Environmentally responsible, safe, and chemoselective catalytic hydrogenation of olefins: ppm level Pd catalysis in recyclable water at room temperature
作者:Balaram S. Takale、Ruchita R. Thakore、Eugene S. Gao、Fabrice Gallou、Bruce H. Lipshutz
DOI:10.1039/d0gc02087g
日期:——
Textbook catalytic hydrogenations are typically presented as reactions done in organic solvents and oftentimes under varying pressures of hydrogen using specialized equipment. Catalysts new and old are all used under similar conditions that no longer reflect the times. By definition, such reactions are both environmentally irresponsible and dangerous, especially at industrial scales. We now report
An Enantiomeric Nanoscale Architecture Obtained from a Pseudoenantiomeric Aggregate: Covalent Fixation of Helical Chirality Formed in Self-Assembled Discotic Triazine Triamides by Chiral Amplification
the achiral triazine triamide soldier component is mixed with a tiny amount of the chiral triazine triamide sergeant component, control of the intrinsic supramolecular helicity of the self-assembled soldier component by the sergeant component leads to chiral amplification and formation of a pseudoenantiomeric aggregate with only one handedness of the helix. The helicity can be preserved by ring-closing
作者:Joaquín Barberá、Laura Puig、Pilar Romero、José Luis Serrano、Teresa Sierra
DOI:10.1021/ja0585477
日期:2006.4.5
assess in solution the presence of the complexes and their tetrameric composition. All the complexes display mesogenic ability, and their mesomorphic organization has been studied by X-ray diffraction and CD spectroscopy. Results allow us to propose a helical columnar model for the mesophase originated from a propeller-like conformation of the supramolecularcomplexes.
此处介绍的研究结果展示了使用液晶和介晶状态中涉及的相互作用来构建复杂分子组织的新示例。我们采用了一种设计策略,其中氢键允许三聚氰胺的 pi 堆积趋势和 V 形分子的横向相互作用能力相结合,这已通过向列、近晶或柱状中间相得到广泛证明。这种组合解决了具有固有螺旋组织的柱状排列的形成。在这项工作中,具有类似于香蕉液晶结构的非介晶和介晶 V 型酸以 3 比 1 的比例与 2,4,6-三氨基-1,3,5-三嗪衍生物络合, 分别。由此获得了氢键超分子,其在溶液中的形成和稳定性已通过红外和核磁共振技术得到证实。DOSY 实验使我们能够在溶液中评估复合物的存在及其四聚体组成。所有配合物都显示出介晶能力,并通过 X 射线衍射和 CD 光谱研究了它们的介晶组织。结果使我们能够为源自超分子复合物的螺旋桨状构象的中间相提出螺旋柱状模型。并通过 X 射线衍射和 CD 光谱研究了它们的介晶组织。结果使我们能够为源自超
Synthesis and Evaluation of a New Series of 3,5-bis((5-bromo-6-methyl-2-<i>t</i>-aminopyrimidin-4-yl)thio)-4<i>H</i>-1,2,4-triazol-4-amines and their Cyclized Products ‘Pyrimidinylthio Pyrimidotriazolothiadiazines’ as 15- Lipo-Oxygenase Inhibitors
A series of new 3,5‐bis((5‐bromo‐6‐methyl‐2‐t‐aminopyrimidin‐4‐yl)thio)‐4H‐1,2,4‐triazol‐4‐amines and their cyclized products ‘pyrimidinylthio pyrimidotriazolothiadiazines’ were designed, synthesized, and evaluated as potential inhibitors of 15‐lipo‐oxygenase (15‐LO). Their syntheses started by initial condensation of 2:1 equivalents of pyrimidine with triazole and subsequent nucleophilic displacement