Nanorod Photocatalysts for C−O Cross‐Coupling Reactions

Abstract

Carbon-heteroatom cross-coupling reactions are significant for numerous industrial chemical processes, in particular for the synthesis of pharmaceuticals, agrochemicals, and biologically active compounds. Photocatalyst/transition metal dual catalytic systems pave a new avenue for organic cross-coupling reactions. Specifically, the use of semiconductor nanoparticles as heterogeneous light sensitizers is highly beneficial for industrial-scale applications owing to their low-cost production, tunable photophysical properties, facile separation, high photostability, and recyclability. Here, CdSe@CdS nanorod photocatalysts are combined with a Ni complex catalyst for the promotion of selective light-induced CÀ O cross-coupling reac-tions between aryl halides and alkyl carboxylic acids. This efficient dual photocatalytic system displays a high yield ( 96 %), with an impressive turnover number (TON) of over 3 × 10 6 , and within a relatively short reaction time as a result of high turnover frequency (TOF) of ~56 s À 1 . In addition, the nanorod photocatalysts harness light with improved solar to product efficiency compared to alternative systems, signaling towards potential solar-powered chemistry. A reaction mechanism involving energy transfer from the nanorods to the Ni complex is proposed and discussed, along with specific benefits of the seeded rod morphology.

Investigation of the Photocatalytic Hydrogen Production of Semiconductor Nanocrystal‐Based Hydrogels

“…Due to the self-supporting porous 3D structure, stirring during the experiments is not necessary to ensure a homogeneous solution, as it is usually the case when NCs are used in photocatalytic reactions. [41,42] This is not least due to the low colloidal stability of the ligand-stabilized NCs in the hole scavenger solution. Mercaptopropionic acid (MPA) stabilized NCs are stable only in the 10 vol % MeOH and TEOA solutions and not in ascorbic acid and Na 2 S/Na 2 SO 3 solutions as demonstrated in Figure S4, Supporting Information, by photographs and dynamic light scattering (DLS) measurements.…”

Visible Light-Mediated Quantum Dot Photocatalysis Enables Olefination Reactions at Room Temperature

“…The quest for finding alternatives to precious metal-based photocatalysts has revolutionized the way chemical reactions are performed in recent years. In this direction, semiconductor nanoparticles or quantum dots (QDs) are emerging as attractive visible-light photocatalysts for performing challenging and useful organic transformations. − In a typical QD photocatalysis, the photoexcited electron–hole pairs are extracted from the core to perform net reductive/oxidative and redox neutral reactions. − With respect to traditional transition-metal complex- and small-organic molecule-based photocatalysts, QDs possess a large visible-light absorption cross section, high charge transfer efficiency, tunable redox potentials, low catalyst loading, superior photostability, and longer shelf-life. − Apart from the properties arising from the core, the surface of QDs (in terms of surface atoms and ligands) can be used as multiple binding sites, as well as for controlling the movement of charge carriers. − On top of this, the ease in QD synthesis from readily available precursors is an added advantage in scaling up their production for industrial level applications. − All these unique properties have rendered QD photocatalysts a special place in organic transformations as well. QD photocatalysts have been predominantly used in organic synthesis for carbon–carbon or carbon–heteroatom coupling reactions, ,,,,− with limited attempts on industrially relevant olefination reactions.…”

Shape tunability of copper nanocrystals deposited on nanorods

“…3 These achievements are attributed to systematical tuning of each component in the colloidal hybrid system. Such tunability allows direct control over the chemical and physical properties 4–6 and enables optimization of functionality alongside endowment for additional applications in catalysis, 7 3D printing, 8 and electronic devices. 9–11…”