Europium‐Catalyzed Aerobic Oxidation of Alcohols to Aldehydes/Ketones and Photoluminescence Tracking

Abstract

Europium is a lanthanide rare-earth metal and is known as a key element in luminophore development. Since europium has two relatively stable oxidation states, Eu 2 + and Eu 3 + , which is exceptional among the various lanthanide elements, we have developed a europium-catalyzed aerobic oxidation with external oxidants utilizing the redox cycle of Eu 2 + /Eu 3 + . The reaction was performed under mild conditions with a wide substrate scope. The photoluminescence spectra clearly demonstrate the oxidation state changes that occur during the presented europium-catalyzed aerobic oxidation.

Surface‐Deactivated Core–Shell Metal–Organic Framework by Simple Ligand Exchange for Enhanced Size Discrimination in Aerobic Oxidation of Alcohols

“…Thus, the combination of a metal catalyst and TEMPO generally shows a higher reaction efficiency and wider substrate scopes than organic oxidant‐only systems. In addition, recently the redox cycle of Eu II /Eu III have been successfully applied to the aerobic oxidation under mild conditions with a similar proposed mechanism . Accordingly, to adopt this catalytic system to heterogeneous catalysts, UiO‐67‐TEMPO with Eu(NO 3 ) 3 was used for aerobic oxidation with a variety of aldehydes with different sizes in the present study (Figure , Tables S1 and S2).…”

MOF‐on‐MOF Architectures: Applications in Separation, Catalysis, and Sensing

“…To obtain this surface‐deactivated MOF‐on‐MOF, we utilized postsynthetic ligand exchange, yielding UiO‐67‐TEMPO‐CS, consisting of a TEMPO‐bearing UiO‐67 core and pure UiO‐67 shell (Figure 7(a)). During the evaluation of the catalytic activity, this series of TEMPO‐functionalized MOFs, in the presence of Eu(NO 3 ) 3 , results in enhanced efficiency and applicable substrate range 34–36 . Although UiO‐67‐TEMPO exhibits moderate size selectivity toward relatively larger alcohols (45% for pyrenyl methanol [1c] and 38% for phenyl pyrenyl methanol [1d]) compared to smaller alcohols (99% for benzyl alcohol [1a] and diphenyl methanol [1b]), such selectivity is still insufficient for catalysis (Figure 7(b)).…”

A Highly Efficient Bismuth Nitrate/Keto-ABNO Catalyst System for Aerobic Oxidation of Alcohols to Carbonyl Compounds under Mild Conditions

“…These results suggest that this reaction system exhibits excellent catalytic ability for the aerobic oxidation of alcohols and could be amenable to scale-up. According to the results above and the literature [40][41][42][43][44][45], a reasonable mechanism for the aerobic oxidation of alcohols catalyzed by Bi(NO 3 ) 3 /Keto-ABNO is proposed in Scheme 5. Under a certain reaction temperature, bismuth nitrate released NO 2 , which was of great significance in the oxidation of Keto-ABNO to Keto-ABNO + .…”