RESUMO
This work presents a straightforward, room-temperature synthesis of a robust {[Fe(atrz)3](OTs)2}n monolith. This approach offers a green alternative to traditional nanoparticle synthesis for manipulating spin crossover (SCO) behaviour. The monolith exhibits a more gradual SCO transition at lower temperatures compared to the bulk material, aligning with observations in smaller particle systems. Notably, the synthesis employs a solvent- and surfactant-free approach, simplifying the process and potentially reducing environmental impact, aligning with the principles of green chemistry.
RESUMO
Covalent organic frameworks (COFs) are porous materials formed through condensation reactions of organic molecules via the formation of dynamic covalent bonds. Among COFs, those based on imine and ß-ketoenamine linkages offer an excellent platform for binding metallic species such as copper to design efficient heterogeneous catalysts. In this work, imine- and ß-ketoenamine-based COF materials were modified with catalytic copper sites following a metallation method, which favored the formation of binding amine defects. The obtained copper-metallated COF materials were tested as heterogeneous catalysts for 1,3-dipolar cycloaddition reactions, resulting in high yields and recyclability.
RESUMO
Layered covalent organic frameworks (2D-COFs), composed of reversible imine linkages and accessible pores, offer versatility for chemical modifications towards the development of catalytic materials. Nitrogen-enriched COFs are good candidates for binding Pd species. Understanding the local structure of reacting Pd sites bonded to the COF pores is key to rationalize interactions between active sites and porous surfaces. By combining advanced synchrotron characterization methods with periodic computational DFT modeling, the precise atomic structure of catalytic Pd sites attached to local defects is resolved within an archetypical imine-linked 2D-COF. This material was synthesized using an inâ situ method as a gel, under which imine hydrolysis and metalation reactions are coupled. Local defects formed inâ situ within imine-linked 2D-COF materials are highly reactive towards Pd metalation, resulting in active materials for Suzuki-Miyaura cross-coupling reactions.
RESUMO
A two-dimensional imine-linked covalent organic framework bearing pyrene has been prepared and exfoliated in water as nanosheets to produce a stable water colloid. As a proof-of-concept, this COF colloid has been used to detect the presence of several organic dyes and polynitro-aromatic derivatives. These results show the high potential of these nanomaterials for applications in chemical sensing of pollutants directly in water.
RESUMO
Schiff-condensation reactions carried out between 1,6-diaminopyrene (DAP) and the tritopical 1,3,5 benzenetricarbaldehyde (BTCA) or 2,4,6-triformylphloroglucinol (TP) ligands give rise to the formation of two-dimensional imine-based covalent-organic frameworks (COFs), named IMDEA-COF-1 and -2, respectively. These materials show dramatic layer-packing-driven fluorescence in solid state arising from the three-dimensional arrangement of the pyrene units among layers. Layer stacking within these 2D-COF materials to give either eclipsed or staggered conformations can be controlled, at an atomic level through chemical design of the building blocks used in their synthesis. Theoretical calculations have been used to rationalize the different preferential packing between both COFs. IMDEA-COF-1 shows green emission with absolute photoluminescence quantum yield of 3.5% in solid state. This material represents the first example of imine-linked 2D-COF showing emission in solid state.
