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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Hydrogen-bonding Assisted Quantum Yield Enhancement and Chromism Activity of 4'-Halo-2'-azaboranils
Teruki Sawada1, Masamichi Yasui1, Takayoshi Arai1
1Soft Molecular Activation Research Center (SMARC), Chiba Iodine Resource Innovation Center (CIRIC), Synthetic Organic Chemistry, Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi, Inage, Chiba, 263-8522, Japan.
Abstract:
By replacing a carbon atom of boranils with a nitrogen atom, azaboranils were newly designed. In the 2'-azaboranils synthesized from 2-aminopyridines with 2-hydroxy-1-naphthaldehyde, the pyridine ring underwent a hydrogen-bonding interaction with the imine proton to restrain the molecular flexibility, which resulted in a significant improvement in luminescence quantum yield in both the solution state and the solid state over those for the parent boranils. The crystalline powder 4'-chloro-2'-azaboranil exhibited mechanochromism and vapochromism in the network of π-π stacking, halogen-bonding, H-F hydrogen-bonding, and CH-π interaction.
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