A series of pyridine-type ligands containing C≡C bonds were designed and synthesized for selective oxidative Heck reaction. These ligands were utilized as functional units and integrated into the skeleton of conjugated microporous polymers. 6,6'-diiodo-2,2'-bipyridine and 1,3,5-triethynylbenzene were polycondensed via Sonogashira cross-coupling strategy to afford CMP-1 material. The resultant CMP-1 was used as a heterogeneous catalytic ligand for the Pd-catalyzed oxidative Heck reaction with high linear selectivity. The linear selectivity of CMP-1 is about 30 times higher than that of bipyridine-based monomer ligand. This work opens a new front of using CMP as an intriguing platform for developing highly efficient catalysts in controlling the regioselectivity in organic reactions.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/jacs.7b00643 | DOI Listing |
Braz Oral Res
January 2025
Pontifícia Universidade Católica do Rio Grande do Sul - PUC-RS, School of Health and Life Sciences, Department of Pediatric Dentistry, Porto Alegre, RS, Brazil.
The emergence of toothpastes containing different abrasive and whitening substances has been a constant concern among dental professionals. The aim of the present study was to perform an in vitro assessment of the surface topography of nanoparticle composite resins subjected to simulated brushing with dentifrices. Test samples were prepared with Filtek Universal (3M ESPE), Filtek Bulkfill (3M ESPE) and Z350 (3M ESPE), with 24 samples per resin.
View Article and Find Full Text PDFAdv Mater
January 2025
Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany.
The rapid advancement of covalent organic frameworks (COFs) in recent years has firmly established them as a new class of molecularly precise and highly tuneable porous materials. However, compared to other porous materials, such as zeolites and metal-organic frameworks, the successful integration of hierarchical porosity into COFs remains largely unexplored. The challenge lies in identifying appropriate synthetic methods to introduce secondary pores without compromising the intrinsic structural porosity of COFs.
View Article and Find Full Text PDFACS EST Air
January 2025
Environmental Engineering Program, University of Colorado Boulder, 1111 Engineering Drive, Boulder, Colorado 80309-0428, United States.
Quantifying changes in the properties of smoke aerosols under varying conditions is important for understanding the health and environmental impacts of exposure to smoke. Smoke composition, aerosol liquid water content, effective density (ρ), and other properties can change significantly as smoke travels through areas under different ambient conditions and over time. During this study, we measured changes in smoke composition and physical properties due to oxidative aging and exposure to humidity.
View Article and Find Full Text PDFOrg Lett
December 2024
Department of Chemistry, Indian Institute of Technology, Kharagpur, West Bengal 721302, India.
Development of metal-free conversion of naturally abundant phenols and anilines to the corresponding olefins remains a formidable challenge. The current state of the art relies on the TM-catalyzed Heck coupling of activated phenols (triflates, tosylates, and more) with the olefins. While these advancements are promising, the reaction suffers from branch vs linear selectivity and requires an expensive TM-ligand combination, hazardous organotin reagents, and very high reaction temperature.
View Article and Find Full Text PDFJ Org Chem
December 2024
Universitaet Potsdam, Institut fuer Chemie, Karl-Liebknecht-Straße 24-25, D-14476 Potsdam-Golm, Germany.
The synthesis of coumarin- and flavonoid-chalcone hybrids via Pd-catalyzed Heck-type coupling of arene diazonium salts and 8-allylcoumarins and -flavonoids is reported. The β-hydride elimination step proceeds with high regioselectivity if an OMOM-substituent is present at the position C7, adjacent to the allyl group. A selective allylic oxidation of the coupling products was accomplished using DDQ in the presence of silica to furnish the chalcones.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!