Chemical Fixation of CO2 and Other Heterogeneous Catalytic Studies by Employing a Layered Cu‐Porphyrin Prepared Through Single‐Crystal to Single‐Crystal Exchange of a Zn Analogue

• Published in: Chemistry, an Asian journal an Asian journal, 2018-01, Vol.13 (1), p.66-72
• Main Authors: Dutta, Gargi, Jana, Ajay Kumar, Natarajan, Srinivasan
• Format: Article
• Language: English
• Subjects: Alkynes; Aromatic compounds; Benzaldehyde; Benzoic acid; Carbon dioxide; Catalysis; Chemical reactions; Chemistry; Copper; Coupling (molecular); Exchanging; Fixation; heterogeneous catalysis; ion exchange; Metal-organic frameworks; Pharmacology; porphyrins; Single crystals; Solvents; structure–activity relationships; Zinc compounds
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.201701384

A solvothermal reaction of Zn(NO3)2⋅6 H2O, tetra‐(4‐pyridyl)porphyrin (H2TPyP), and 4,4′‐oxybis(benzoic acid) (H2OBA) resulted in a new two‐dimensional Zn‐ porphyrin metal–organic framework compound, [Zn2(C40H24N8)0.5(C14H8O5)(DMA)](DMA)(H2O)6 (1; DMA=N,N‐dimethylacetamide). The ZnII ions present in 1 could be exchanged by using a solution of Cu(NO3)2⋅3 H2O in DMA at room temperature to give [Cu2(C40H24N8)0.5(C14H8O5)(DMA)](DMA)(H2O)3 (Cu∈1). The extra‐framework solvent molecules have been shown to be reversibly removed or exchanged without collapse of the framework. Solvent‐free Cu∈1 was explored as an active heterogeneous catalyst towards three different organic reactions: 1) the chemical fixation of CO2 into cyclic carbonate at room temperature and 1 atm; 2) the nitroaldol reaction under solvent‐free conditions, and 3) the three‐component coupling of aminopyridine, benzaldehyde, and aryl alkynes followed by 5‐exo‐dig cyclization to produce the important pharmacophore imidazopyridine. Exchange studies: The synthesis, structure, and Cu‐exchange (single‐crystal‐to‐single‐crystal fashion) of a porphyrin‐based metal–organic framework is described. The copper‐exchanged compound exhibits catalytic activity towards the chemical fixation of CO2 under ambient conditions, the nitroaldol reaction, and the three‐component coupling reaction (see figure).