Sustainable and Bench‐Stable Photoactive Aqueous Nanoaggregates of Cu(II) for ppm Level Cu(I) Catalysis in Water

Abstract

The nanomaterial containing amphiphile-stabilized mononuclear Cu(II) is developed. The material is characterized by various spectroscopic techniques, such as X-ray absorption spectrscopy (XAS), high-resolution transmission electron microscopy, nuclear magnetic resonance (NMR), UV-vis, and infrared spectroscopies. Since the structural data for the amphiphile-bound Cu(II) center is not available, a theoretical model based on DFT calculations is employed. The analyses based on NMR spectroscopic data, including the isotope labeling, support that the tertiary amide group of the amphiphile binds to the Cu surface. Likewise, the bond distances found by XAS spectroscopy agree with the theoretical model. Time-dependent DFT studies predict that the low-lying excited state has a dominant ligand-to-metal charge transfer (LMCT) character. Cu(II) changes to Cu(I) assisted by the LMCT excitation upon visible light irradiation, generating robust catalytically active species. The catalytic activity for domino azidation-[3+2] cycloaddition reactions in water is investigated. The catalytic protocol is applicable on various substrates, and the catalytic material is stable under ambient conditions for up to three months.

Micelle-Derived Palladium Nanoparticles for Suzuki–Miyaura Coupling Reactions in Water at Room Temperature

“…The hydrophobic pockets in these aggregates hold oleophilic substrates together to “dissolve” them in water, which can resolve the solubility issues of organic substrates in water . Therefore, commercially available surfactants such as sodium dodecyl sulfate (SDS), , hexadecyl trimethyl ammonium bromide (CTAB), , and polyoxyethylene 23 lauryl ether (Brij35) , and newly designed surfactants such as TPGS-750-M, − PS-750-M, − PTS, , and Nok , have been employed to promote a variety of reactions. The morphology of the aggregates is an important concern in the success of reactions because of the great relevance to solubilization and mass transfer of organic substrates.…”

Aqueous micellar technology: an alternative beyond organic solvents

“…Combining this concentration effect with the shielding effect, we explored the stability of ligand- or antioxidant-free Cu( i ) species for one-pot azidation via S N Ar and Cu( i )-catalyzed azide-alkyne cycloaddition reaction. 19 Generally, the +1-oxidation state of Cu is unstable in water and requires a reductant or specific ligands or support to maintain that oxidation state. The addition of CuI and NaN 3 into an aqueous solution of PS-750-M, followed by visible light irradiation, generates a nanomaterial containing PS-750-M, Cu, and azide (Scheme 5).…”

“…In January 2020, she began her PhD studies under the supervision of Prof. Besides, it promotes metal-micelle binding, 13,14 enables the photoredox activity of Cu(II) for ppm level catalysis, 19 and provides shielding to water-sensitive reaction intermediates. 15,20 PS-750-M has a tertiary amide functional group connecting a polar mPEG chain with the non-polar hydrocarbon chain via a proline linker.…”

“…12,13,15,16 Likewise, they can preserve the pseudostable oxidation state of a metal, such as ligand-free Cu(I) species in ultrasmall NP form. 19 The optimal binding constant between such sensitive species and micelles (also known as metal-micelle binding) is responsible for such unanticipated stability. It results in reactivity that would otherwise require dry organic solvents or is not efficiently possible in organic media due to concentration and hydrophobic effects provided by the micelles.…”

Water-Soluble Copper(I) Hydroxide Catalyst and Its Formation in Ligand-Free Suzuki–Miyaura Cross-Coupling Reactions

“…Recently, Cu has reemerged as an alternative metal for metal-catalyzed cross-coupling reactions because of its cost-effectiveness, readily availability, and less toxicity. − , Many studies have been reported for non-SM types of homogeneous ligand-stabilized Cu-catalyzed cross-coupling reactions. A survey of the literature shows that Cu­(I) complexes stabilized with β-diketones, phosphines, or 1,10-phenanthrolines were generally reported as the catalytical species in the Cu-catalyzed cross-coupling reactions. − The chemical identity of the active Cu­(I) species depended on the oxidation states of the Cu precursors (i.e., Cu(0), Cu­(I), ,,, or Cu­(II) , ) and types of stabilizing ligands.…”