Cu(OAc) 2 ‐porphyrins as an efficient catalytic system for base‐free, nature mimicking Chan–Lam coupling in water

Fixing CO2 under Atmospheric Conditions and Dual Functional Heterogeneous Catalysis Employing Cu MOFs: Polymorphism, Single-Crystal-to-Single-Crystal (SCSC) Transformation and Magnetic Studies

New copper compounds, [Cu(C14H8O6)(C10H8N2)(H2O)] (1), [Cu(C14H8O6)(C10H8N2)(H2O)]·(C3H7ON)2 (2), [Cu(C14H8O6)(C10H8N2)(H2O)2]·(C3H7ON) (3), [Cu(C14H8O6)(C10H8N4)] (4), and [Cu(C14H8O6)(C10H8N4)]·(H2O) (5), were prepared employing 2,5-bis(prop-2-yn-1-yloxy)terephthalic acid (2,5-BPTA) as the primary ligand and 4,4'-bipyridine (1-3) and 4,4'-azopyridine (4-5) as the secondary ligands. Single-crystal studies indicated that compounds 1-4 have two-dimensional layer structures and compound 5 has a three-dimensional structure. Compounds 1-3 were isolated from the same reaction mixture but by varying the time of reaction. The framework structures of compounds 1-3 are similar and may be considered as polymorphic structures. Compounds 4 and 5 can also be considered polymorphic with a change in dimensionality of the structure. Compounds 1-3 can be formed through a single-crystal-to-single-crystal transformation under a suitable solvent mixture. The Cu center was explored for the Lewis acid-catalyzed cycloaddition reaction of epoxide and CO2 under ambient conditions in a solventless condition and also for the synthesis of propargylamine derivatives by three-component coupling reactions (A3 coupling) in a DCM medium. The Lewis basic functionality of the MOF (-N═N- group) has been explored for the Henry reaction (aldol condensation) in a solventless condition. In all of the catalytic reactions, good yields and recyclability were observed. The magnetic studies indicated that compounds 1 and 4 have antiferromagnetic interactions and compound 5 has ferromagnetic interactions. The present studies illustrated the rich diversity that the copper-containing compounds exhibit in extended framework structures.

Porphyrin N-Pincer Pd(II)-Complexes in Water: A Base-Free and Nature-Inspired Protocol for the Oxidative Self-Coupling of Potassium Aryltrifluoroborates in Open-Air

Metalloporphyrins (and porphyrins) are well known as pigments of life in nature, since representatives of this group include chlorophylls (Mg-porphyrins) and heme (Fe-porphyrins). Hence, the construction of chemistry based on these substances can be based on the imitation of biological systems. Inspired by nature, in this article we present the preparation of five different porphyrin, meso-tetraphenylporphyrin (TPP), meso-tetra(p-anisyl)porphyrin (TpAP), tetrasodium meso-tetra(p-sulfonatophenyl)porphyrin (TSTpSPP), meso-tetra(m-hydroxyphenyl)porphyrin (TmHPP), and meso-tetra(m-carboxyphenyl)porphyrin (TmCPP) as well as their N-pincer Pd(II)-complexes such as Pd(II)-meso-tetraphenylporphyrin (PdTPP), Pd(II)-meso-tetra(p-anisyl)porphyrin (PdTpAP), Pd(II)-tetrasodium meso-tetra(p-sulfonatophenyl)porphyrin (PdTSTpSPP), Pd(II)-meso-tetra(m-hydroxyphenyl)porphyrin (PdTmHPP), and Pd(II)-meso-tetra(m-carboxyphenyl)porphyrin (PdTmCPP). These porphyrin N-pincer Pd(II)-complexes were studied and found to be effective in the base-free self-coupling reactions of potassium aryltrifluoroborates (PATFBs) in water at ambient conditions. The catalysts and the products (symmetrical biaryls) were characterized using their spectral data. The high yields of the biaryls, the bio-mimicking conditions, good substrate feasibility, evading the use of base, easy preparation and handling of catalysts, and the application of aqueous media, all make this protocol very attractive from a sustainability and cost-effective standpoint.