Results 91 to 100 of about 3,741,215 (311)

Unraveling hidden symmetry breaking in racemic compounds

Proceedings of the National Academy of Sciences
Racemic compounds, consisting of an equimolar mixture of enantiomers in crystalline form, are conventionally regarded as fully symmetric and are often dismissed as a trivial phenomenon due to their abundance—as they account for a substantial fraction (90 to 95%) of entries in structural databases.
Weihao Wang, Fangyi Chen, Zhenghong Chen, Yutong Sun, Feng Liu, Shaodong Zhang   +5 more
openaire   +3 more sources

Local Solvent Ordering Drives Supramolecular Chirality Inversion

Advanced Science, EarlyView.
Local solvent organization is shown to govern supramolecular chirality by selecting distinct chiral assembly pathways. A subtle change in water‐DMSO composition reverses the helical sense of a chiral perylene bisimide, while heating induces an irreversible thermal inversion to a more stable enantiomorph.
Triza Pal, Akta Singh, Subinoy Adhikari, Jagannath Mondal, Debangshu Chaudhuri   +4 more
wiley   +1 more source

Influence of solvent and the operating conditions on the crystallization of racemic mandelic acid [PDF]

, 2004
The crystallization of racemic mandelic acid is studied in unseeded batch cooling experiments in four solvent systems. Apart from the thermodynamically stable racemic compound, a metastable modification of the racemic compound is also found to initially ...
Rasmuson, Åke C.,, Profir, Veronica M.,
core   +1 more source

Divergent Synthesis of Möbius and Hückel N‐Heterocycloarenes From a Common Macrocyclic Backbone

Angewandte Chemie, EarlyView.
In the divergent synthesis of Möbius and Hückel N‐heterocycloarenes from a common macrocyclic precursor, the annulation reaction dictates topology: Scholl reaction gives Möbius topology, while InCl3‐mediated alkyne annulation gives Hückel topology. The Möbius N‐heterocycloarene is unevenly contorted as revealed by crystal structure, and the Hückel N ...
Han Chen, Huishu Ma, Daiyue Yang, Zheng Zhou, Xiao Chen, Zhifeng Huang, Qian Miao   +6 more
wiley   +2 more sources

Cobalt‐Catalyzed Asymmetric Construction of Boron Stereocenters With C–N Axial Chirality

Advanced Science, EarlyView.
A cobalt/Salox‐catalyzed one‐pot annulation enables enantioselective formation of B‐stereogenic centers and C─N axial chirality via C─H/N─H annulation, affording diverse fluorescent products with high stereocontrol and optoelectronic potential. ABSTRACT The efficient construction of boron stereogenic centers alongside axial chirality remains a ...
Subramani Kumaran, Harihara Subramanian Ravi Sankar, Pritam Maity, J. Richard Premkumar, Abir Das, Basker Sundararaju   +5 more
wiley   +1 more source

Supramolecular Polymerization and Morphological Transformation of Dynamic Helical Poly(Phenylacetylene)s via Chain‐End Host–Guest Interactions

Angewandte Chemie, EarlyView.
A helical polymer whose chain ends are connected through pillar[5]arene‐based host–guest interactions translates molecular helicity into supramolecular morphology. Solvent‐triggered helicity inversion accompanied by changes in chain rigidity switches the supramolecular architecture between cyclic and rigid‐rod nanostructures.
Tatsuya Nishimura, Haru Nozue, Feng Li, Tomoki Ogoshi, Katsuhiro Maeda   +4 more
wiley   +2 more sources

NiH‐Catalyzed Enantio‐ and Regioselective Hydroselenylation of Unactivated Alkenes

Advanced Science, EarlyView.
Nickel‐hydride‐catalyzed enantio‐ and regioselective hydroselenylation of unactivated alkenes provides access to chiral organoselenium compounds. Enantiodetermining Ni–H insertion followed by single‐electron diselenide activation generates selenyl radical.
Hyung‐Joon Kang, Jaehun Kim, Sungwoo Hong   +2 more
wiley   +1 more source

Synthesis of Six Natural Products Enabled by Selective Hydroxylation of Orcinaldehyde‐Like Substrates With an Enzyme Library

Angewandte Chemie, EarlyView.
Achieving selective (sp3)C–H hydroxylation can streamline the synthesis of complex organic molecules. Biocatalysis presents an opportunity to realize this transformation, however, identifying useful enzymes that enable synthetic strategies can be a challenge due to limitations in enzyme substrate scope.
Gonzalo J. Villegas Rodríguez, Evan O. Romero, Jonathan C. Perkins, Diego N. Rojas, Maximilian S. Hrigora, Alison R. H. Narayan   +5 more
wiley   +2 more sources

Chiral Morphing of Liquid Crystal Polymer Networks

Advanced Science, EarlyView.
This paper reviews how macroscopic chirality spontaneously arises from liquid crystal polymer materials. It describes how alignment is utilized to create the mechanical anisotropy, geometric misorientation and asymmetry that leads to chiral shape morphing, how shape selection between helicoids and helices arises, the techniques used to prepare these ...
Laurens T. de Haan
wiley   +1 more source

Heat‐ and Light‐Directed Cycloadditions Enable a Pericyclic Cascade Reaction From a Molecular Precursor

Angewandte Chemie, EarlyView.
A multi‐stimuli‐responsive material is designed that responds to light, heat, and mechanical force through distinct chemical reaction pathways. The pathway is directed by self‐assembly and the applied stimulus. A novel pericyclic reaction cascade is also achieved, and the mechanism is supported through density functional theory calculations.
Liulei Ma, Bella Albano, Gary C. George III, Steven A. Lopez, Kristin M. Hutchins   +4 more
wiley   +2 more sources