Gold nanorods show great potential in harvesting natural sunlight and generating hot charge carriers that can be employed to produce electrical or chemical energies. We show that photochemical reduction of Pt(IV) to Pt metal mainly takes place at the ends of gold nanorods (AuNRs), suggesting photon-induced hot electrons are localized in a time-averaged manner at AuNR ends. To use these hot electrons efficiently, a novel synthetic method to selectively overgrow Pt at the ends of AuNRs has been developed. These Pt-end-capped AuNRs show relatively high activity for the production of hydrogen gas using artificial white light, natural sunlight, and more importantly, near IR light at 976 nm. Tuning of the surface plasmon resonance (SPR) wavelength of AuNRs changes the hydrogen gas production rate, indicating that SPR is involved in hot electron generation and photoreduction of hydrogen ions. This study shows that gold nanorods are excellent for converting low-energy photons into high-energy hot electrons, which can be used to drive chemical reactions at their surfaces.
An efficient kinetic resolution of axially chiral 5- or 8-substituted quinoline derivatives was developed through asymmetric transfer hydrogenation of heteroaromatic moiety, simultaneously obtaining two kinds of axially chiral skeletons with up to 209 of selectivity factor. This represents the first successful application of asymmetric transfer hydrogenation of heteroaromatics in kinetic resolution of axially chiral biaryls.
A concise deracemization of racemic secondary and tertiary amines with a tetrahydroisoquinoline core has been successfully realized by orchestrating a redox process consisted of N-bromosuccinimide oxidation and iridum-catalyzed asymmetric hydrogenation. This compatible redox combination enables one-pot, single-operation deracemization to generate chiral 1-substituted 1,2,3,4-tetrahydroisoquinolines with up to 98% ee in 93% yield, offering a simple and scalable synthetic technique for chiral amines directly from racemic starting materials.
Glycerol is one of the most crucial by-products in the production of biodiesel, and owing to its oversaturation in the market, several synthetic strategies have been developed to transform it into other higher value-added products such as glycerol carbonate, epichlorohydrin, 1,3-propanediol, etc. Amongst them, glycerol carbonate is considered to be the most valuable product. Considering the facile separation and reusability of catalyst, heterogeneous base catalysts have attracted considerable attention due to the obvious advantages over Brϕnsted acid and homogeneous base catalysts in the transesterification of glycerol. Herein, we will give a short overview on the recent development of the heterogeneous catalysis in the transesterification of glycerol with dialkyl carbonate. Focus will be concentrated on the heterogeneous base catalysts including alkaline-earth metal oxides (MgO, CaO, and mixed oxides), hydrotalcites, zeolites, clinoptilolites, organic bases, etc. Their catalytic mechanisms during the heterogeneous process will be elucidated in detail.
By employing halogenide trichloroisocyanuric acid as a traceless activation reagent, a general iridium-catalyzed asymmetric hydrogenation of isoquinolines and pyridines is developed with up to 99% ee. This method avoids tedious steps of installation and removal of the activating groups. The mechanism studies indicated that hydrogen halide generated in situ acted as an activator of isoquinolines and pyridines.
A highly enantioselective hydrogenation of heteroaromatics bearing a hydroxyl group, 3-hydroxypyridinium salts, has been successfully developed using chiral iridium catalyst, providing a direct access to trans 6-substituted piperidin-3-ols with up to 95% ee. Swern oxidation of the hydrogenation products affords chiral 6-substituted piperidin-3-ones, which are easily reduced to cis 6-substituted piperidin-3-ols using K-selectride.
In this review, we summarize the chemistry of water compatible supramolecular polymers (WCSPs) based on the core supramolecular approaches at play, namely hydrogen-bonding arrays, electrostatic interactions, large π-conjugated subunits, host–guest interactions, and peptide-based systems, respectively. We discuss both synthesis and polymer structure, as well as the underlying design expectations and potential applications.
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