A Deep Cavitand Receptor Functionalized with Fe(II) and Mn(II) Aminopyridine Complexes for Bioinspired Oxidation Catalysis

Abstract

A deep cavitand receptor 2 based on a resorcinarene scaffold and functionalized with a bis(pyridyl)dipyrrolidine tetradentate ligand has been obtained. Binding of divalent metal ions (M 2+ = Mn 2+ , Fe 2+ and Zn 2+) at the tetradentate ligand results in the formation of cavitand complexes 2•M(OTf) 2. The complexes exhibit selective binding of alkylammonium ions and amides within the cavitand. 2•M(OTf) 2 (M = Fe(II) and Mn(II)) catalyze selective hydroxylation of aliphatic C-H bonds and epoxidation of olefins with hydrogen peroxide, exhibiting selectivity patterns consistent with the implication of high valent metal-oxo species. Furthermore, 2•Fe(OTf) 2 reacts with IO 4 to form an oxoiron(IV) complex [2•Fe(O)] 2+ , without decomposition of the supramolecular container. This species is relatively stable at 0 °C, yet engages in fast oxygen atom transfer reactions.

Fe-doped H3PMo12O40 immobilized on covalent organic frameworks (Fe/PMA@COFs): a heterogeneous catalyst for the epoxidation of cyclooctene with H2O2

“…22 On the other hand, numerous transition metal complexes of iron have been investigated as alkene epoxidation catalysts. [23][24][25][26] Costas and coworkers developed a series of Fe-pdp catalysts with chiral tetradentate ligands for the epoxidation of a wide range of olens. 27 In this work, iron coordination complexes bearing tetradentate aminopyridine ligands are shown to constitute a privileged platform for epoxidation.…”

Velcrand Functionalized Polyethylene

“…Cavitands are programmable synthetic receptors capable of hosting shape complementary guests through specific weak interactions, such as hydrogen bonding, π-π stacking, and CH-π and cation-π interactions [ 1 ]. Their remarkable and versatile molecular recognition properties have been exploited in many different fields, including catalysis [ 2 , 3 , 4 , 5 ], crystal engineering [ 6 ], molecular grippers [ 7 ], amino acids [ 8 , 9 ] and protein recognition [ 10 , 11 ], responsive nanostructures [ 12 , 13 ], and sensing [ 14 , 15 ].…”

Solvent-responsive cavitand lanthanum complex

“…[1][2][3][4][5] In this context, macrocyclic compounds, like calixarenes and cavitands with their unique shape and recognition properties, have been widely exploited as multidentate ligands. [6][7][8][9][10][11][12][13][14][15][16] The resulting coordination complexes have found application in many fields, including mimic biological systems, 12,17,18 catalysis, [19][20][21] molecular machines, 14 guest adsorption 22,23 , the development of metal organic frameworks 9,16,[24][25][26] and tuning liquidcrystalline behaviour. 15 The design of systems that respond to an external stimulus are a major goal of supramolecular chemistry.…”