Imine-linked ILCOF-1 based on 1,4-phenylenediamine and 1,3,6,8-tetrakis(4-formylphenyl)pyrene was converted through consecutive linker substitution and oxidative cyclization to two isostructural covalent organic frameworks (COFs), having thiazole and oxazole linkages. The completeness of the conversion was assessed by infrared and solid-state NMR spectroscopies, and the crystallinity of the COFs was confirmed by powder X-ray diffraction. Furthermore, the azole-linked COFs remain porous, as shown by nitrogen sorption experiments. The materials derived in this way demonstrate increased chemical stability, relative to the imine-linked starting material. This constitutes a facile method for accessing COFs and linkages that are otherwise difficult to crystallize due to their inherently limited microscopic reversibility.
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http://dx.doi.org/10.1021/jacs.8b05830 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Sichuan University, School of Chemical Engineering, No.24 South Section 1, Yihuan Road, 610065, Chengdu, CHINA.
Covalent organic frameworks (COFs) are often employed in oxygen reduction reactions (ORR) for hydrogen peroxide production due to their tunable structures and compositions. However, COF electrocatalysts require precise structural engineering, such as heteroatoms or metal site doping, to modulate the reaction pathway during the ORR process. In this work, we designed a tetraphenyl-p-phenylenediamine based COF electrocatalyst, namely TPDA-BDA, which exhibited excellent two-electron (2e) ORR performance with high H2O2 selectivity of 89.
View Article and Find Full Text PDFNanoscale
January 2025
Department of Chemistry, Indian Institute of Technology Patna, Patna 801106, Bihar, India.
Covalent organic frameworks (COFs) are crystalline porous materials bearing well-ordered two- or three-dimensional molecular tectons in their polymeric skeletal framework. COFs are structurally robust as well as physiochemically stable. Currently, these are being developed for their use as "heterogeneous catalysts" for various organic transformations.
View Article and Find Full Text PDFChem Asian J
January 2025
Northeast Agricultural University, College of Horticulture and Landscape Architecture, CHINA.
In last few decades, the agriculture sector is facing various type of crops diseases originated by crop pests. Among various crops the tomato plant is greatly affected by many pests such as aphids and whiteflies, which are badly decreasing tomato plant yield and effecting its growth. In last few years, various type of pesticides such as Neonicotinoids and Pyrethroids are employed with are badly effecting eco system and water bodies.
View Article and Find Full Text PDFMolecular junctions (MJs) are celebrated nanoelectronic devices for mimicking conventional electronic functions, including rectifiers, sensors, wires, switches, transistors, negative differential resistance, and memory, following an understanding of charge transport mechanisms. However, capacitive nanoscale molecular junctions are rarely seen. The present work describes electrochemically (E-Chem) grown covalently attached molecular thin films of 10, 14.
View Article and Find Full Text PDFRSC Adv
January 2025
Dipartimento di Scienze e Innovazione Tecnologica, Università Del Piemonte Orientale A. Avogadro Viale T. Michel 11 15121 Alessandria Italy
A novel synthesis of a nanometric MCM-41 from biogenic silica obtained from rice husk is here presented. CTABr and Pluronic F127 surfactants were employed as templating agents to promote the formation of a long-range ordered 2D-hexagonal structure with cylindrical pores and to limit the particle growth at the nanoscale level thus resulting in a material with uniform particle size of 20-30 nm. The physico-chemical properties of this sample (RH-nanoMCM) were investigated through a multi-technique approach, including PXRD, Si MAS NMR, TEM, -potential and N physisorption analysis at 77 K.
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