Vinylene‐Linked Covalent Organic Frameworks by Base‐Catalyzed Aldol Condensation

Abstract

Two2 Dc ovalent organic frameworks (COFs) linked by vinylene (À CH = CH À)g roups (V-COF-1 and V-COF-2) are synthesized by exploiting the electron deficient nature of the aromatic s-triazine unit of C 3-symmetric 2,4,6trimethyl-s-triazine (TMT). The acidic terminal methyl hydrogens of TMT can easily be abstracted by ab ase,r esulting in as tabilized carbanion, whichf urther undergoes aldol condensation with multitopic aryl aldehydes to be reticulated into extended crystalline frameworks (V-COFs). Both V-COF-1(with terepthalaldehyde (TA)) and V-COF-2 (with 1,3,5tris(p-formylphenyl)benzene (TFPB)) are polycrystalline and exhibit permanent porosity and BET surface areas of 1341 m 2 g À1 and 627 m 2 g À1 ,r espectively.O wing to the close proximity (3.52)o ft he pre-organized vinylene linkages within adjacent 2D layers stacked in eclipsed fashion, [2+ +2] photo-cycloadditon in V-COF-1 formed covalent crosslinks between the COF layers.

Transition Metal Ions Regulated Structural and Catalytic Behaviors of Coordination Polymers

“…Considerable efforts have been devoted to preparing an organic ligand with versatile coordination sites to promote the construction of higher dimensional, robust, and emerging multifunctional framework materials. In this perspective, coordination polymers (CPs) and metal–organic frameworks (MOFs) are the most prominent outcomes with porous crystalline nature, lowest framework density, and inorganic nodes constituted by metal ions/clusters coordinated with organic moieties containing at least two requisite binding sites. − Such polymeric frameworks have become the center of attraction for researchers to carry out diverse applications in selective gas storage and gas adsorption, − ion-exchange, − separation, − conductivity, − drug delivery, − sensor devices, − and various catalysis like autocatalysis, biocatalysis, photocatalysis, organo-catalysis, along with electrocatalysis. − At present, a large number of metal centered catalysts are available for Lewis-acid-based catalytic transformations in well-known reactions like cyanosilylation, − Diels–Alder, Ene reaction, aldol reaction, , ketalization, etc. − In several catalytic reactions, CPs/MOFs work effectively as precatalysts, cocatalysts, cooperative catalysts, and promoters to accelerate the formation of valuable products for large scale applications. The catalytic activities of CPs/MOFs alter due to the number of donor sites in organic ligands, available functional groups in ligands such as basic (NH 2 ) and acidic groups (OH and SO 3 H), oxidation states of metals or metal-clusters, ionic sizes, shapes, and geometries of complexes .…”

“…1−3 Such polymeric frameworks have become the center of attraction for researchers to carry out diverse applications in selective gas storage and gas adsorption, 4−7 ion-exchange, 8−10 separation, 11−13 conductivity, 14−16 drug delivery, 17−19 sensor devices, 20−22 and various catalysis like autocatalysis, biocatalysis, photocatalysis, organo-catalysis, along with electrocatalysis. 23−27 At present, a large number of metal centered catalysts are available for Lewis-acid-based catalytic transformations in well-known reactions like cyanosilylation, 28−33 Diels−Alder, 34 Ene reaction, 35 aldol reaction, 36,37 ketalization, etc. 38−41 In several catalytic reactions, CPs/MOFs work effectively as precatalysts, cocatalysts, cooperative catalysts, and promoters to accelerate the formation of valuable products for large scale applications.…”

Nature-Inspired Pyrylium Cation-Based Vinylene-Linked Two-Dimensional Covalent Organic Framework for Efficient Sunlight-Driven Water Purification

“…The successful formation of the crystalline v-2D-COF-O1 was explicitly confirmed by the comparison between experimental and simulated PXRD patterns (Figure a). According to the simulated PXRD, the peaks at 5.8 and 10° can be assigned to the (100) and (200) crystal facets, respectively. , The atomistic structure for the multilayered v-2D-COF-O1 was constructed starting from eclipsed (AA) stacking mode of two monolayers in the unit cell, which was subject of geometry optimization in a fully flexible cell. Upon cell and ionic position optimization the structure converged in the inclined AA stacking mode (Figure S1 and Table S2).…”

Ultrathin Covalent Organic Framework Anchored on Graphene for Enhanced Organic Pollutant Removal

“…In the design of COF‐based adsorbents, one key issue that needs to be taken more thoroughly into account is the required pore size and pore accessibility for a given dye molecule, i.e., whether the dye molecule can easily gain access to the inside of the pores. The majority of the COFs currently reported are furnished with one‐dimensional (1D) channels with an aperture size in the range of 1–4 nm [16–20] . The micropore or small mesopore characteristics and the highly stacked nature of the structure restrict the dye molecules from quickly entering the interior of the pores, with some materials even suffering from pore blockage during dye adsorption, which leads to low water purification efficiency.…”