Jannik Brückmann

The bay‐decoration of perylenediimide (PDI) through C−C bond formation was achieved via Suzuki–Miyaura couplings using a dinitro precursor as a nitroarene electrophilic partner, this highlighting its unique reactivity in comparison with its brominated analog. This strategy allows an easy asymmetric π‐decoration of the PDI core, to reach D‐π‐D’ or D‐π‐A triads, opening horizons for this new class of functional materials. More information can be found in the Full Paper by P. Hudhomme et al. (DOI: https://doi.org/10.1002/chem.20200342010.1002/chem.202003420).

The bay decoration of perylenediimide (PDI) through C−C bond formation was achieved by Suzuki–Miyaura couplings using a dinitro precursor. The unique reactivity of this electrophilic partner in comparison with its brominated analogue is highlighted and it allows for the first easy asymmetric π‐decoration of the PDI core, opening new horizons for this new class of functional materials.

Abstract

Bay decoration of perylenediimide (PDI) is an attractive approach for tuning the optoelectronic properties of the dye as well as breaking backbone planarity, which provides the possibility of preventing the undesired formation of aggregates. This is usually performed through successive bis‐bromination of PDI and pallado‐catalyzed cross‐coupling, which leads to symmetric triads. We now describe an efficient synthetic strategy for desymmetrization of the accepting PDI core by starting from its bis‐nitration. To this end, Suzuki–Miyaura Couplings (SMC) were carried out on a mixture of 1,6‐ and 1,7‐dinitroPDI regioisomers to add triphenylamine donating moieties and obtain donor–acceptor–donor triads. Investigation of the reactivity of dinitro PDI derivatives toward SMC has allowed us to access unprecedented asymmetric π‐conjugated PDI‐centered triads. These 1,6‐ and 1,7‐PDI based triads, prepared as regioisomeric mixtures, were successfully separated and their spectroscopic, crystallographic and optoelectronic differences are reported.

The first catalytic asymmetric synthesis of Remdesivir by the coupling of the P‐racemic phosphoryl chloride with protected nucleoside GS441524 has been realized using a chiral bicyclic imidazole catalyst, which is crucial for the racemization process involving the phosphoryl chloride and subsequent stereodiscriminating step (96 % conv., 22:1 S _P:R _P). Furthermore, a 10 gram scale reaction was successfully realized, showing its potential for industrial application.

Abstract

The catalytic asymmetric synthesis of the anti‐COVID‐19 drug Remdesivir has been realized by the coupling of the P‐racemic phosphoryl chloride with protected nucleoside GS441524. The chiral bicyclic imidazole catalyst used is crucial for the dynamic kinetic asymmetric transformation (DyKAT) to proceed smoothly with high reactivity and excellent stereoselectivity (96 % conv., 22:1 S _P:R _P). Mechanistic studies showed that this DyKAT is a first‐order visual kinetic reaction dependent on the catalyst concentration. The unique chiral bicyclic imidazole skeleton and carbamate substituent of the catalyst are both required for the racemization process, involving the phosphoryl chloride, and subsequent stereodiscriminating step. A 10 gram scale reaction was also conducted with comparably excellent results, showing its potential for industrial application.

Bow to demands : A new mode of contortion in perylene diimides has been investigated, where the molecule is bent along its long axis like a bow. By adjusting the tension in the strings of the bow, the degree of bending can be controlled from flat to highly bowed. The important finding is that the bowing results not only in red‐shifted absorptions but also in more facile reductions.

Abstract

This study explores a new mode of contortion in perylene diimides where the molecule is bent, like a bow, along its long axis. These bowed PDIs were synthesized through a facile fourfold Suzuki macrocyclization with aromatic linkers and a tetraborylated perylene diimide that introduces strain and results in a bowed structure. By altering the strings of the bow, the degree of bending can be controlled from flat to highly bent. Through spectroscopy and quantum chemical calculations, it is demonstrated that the energy of the lowest unoccupied orbital can be controlled by the degree of bending in the structures and that the energy of the highest occupied orbital can be controlled to a large extent by the constitution of the aromatic linkers. The important finding is that the bowing results not only in red‐shifted absorptions but also more facile reductions.

Polyoxometalate chemistry has shown great application potential in the field of catalysis. This Minireview outlines and discusses the advantages, recent advances, challenges, strategies and future development of POM‐based compounds as photo/electrocatalysts in hydrogen evolution reaction, oxygen evolution reaction, and CO₂ reduction reaction.

Abstract

Photo/electrocatalysis of water (H₂O) splitting and CO₂ reduction reactions is a promising strategy to alleviate the energy crisis and excessive CO₂ emissions. For the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and CO₂ reduction reaction (CO₂RR) involved, the development of effective photo/electrocatalysts is critical to reduce the activation energy and accelerate the sluggish dynamics. Polyoxometalate (POM)‐based compounds with tunable compositions and diverse structures are emerging as unique photo/electrocatalysts for these reactions as they offer unparalleled advantages such as outstanding solution and redox stability, quasi‐semiconductor behaviour, etc. This Minireview provides a basic introduction related to photo/electrocatalytic HER, OER and CO₂RR, followed by the classification of pristine POM‐based compounds toward different catalytic reactions. Recent breakthroughs in engineering POM‐based compounds as efficient photo/electrocatalysts are highlighted. Finally, the advantages, challenges, strategies and outlooks of POM‐based compounds on improving photo/electrocatalytic performance are discussed.

A rhodium complex immobilized in a bipyridine‐based periodic mesoporous organosilica, Rh@PMO, exhibited high catalytic activity during transfer hydrogenation, even in the presence of a protein, indicating excellent tolerance for the protein due to the size‐sieving effect of the PMO. A mixture of Rh@PMO and an alcohol dehydrogenase promoted sequential reactions to afford an enantiomeric product with high conversion and enantioselectivity.

Abstract

The combined use of a metal‐complex catalyst and an enzyme is attractive, but typically results in mutual inactivation. A rhodium (Rh) complex immobilized in a bipyridine‐based periodic mesoporous organosilica (BPy‐PMO) shows high catalytic activity during transfer hydrogenation, even in the presence of bovine serum albumin (BSA), while a homogeneous Rh complex exhibits reduced activity due to direct interaction with BSA. The use of a smaller protein or an amino acid revealed a clear size‐sieving effect of the BPy‐PMO that protected the Rh catalyst from direct interactions. A combination of Rh‐immobilized BPy‐PMO and an enzyme (horse liver alcohol dehydrogenase; HLADH) promoted sequential reactions involving the transfer hydrogenation of NAD⁺ to give NADH followed by the asymmetric hydrogenation of 4‐phenyl‐2‐butanone with high enantioselectivity. The use of BPy‐PMO as a support for metal complexes could be applied to other systems consisting of a metal‐complex catalyst and an enzyme.

The going rate: Recently, modern polymer chemistry has been utilized to construct macromolecular supports around the butterfly [2Fe‐2S] active‐site mimetics of [FeFe] hydrogenases to improve the catalysis of hydrogen production. This Minireview summarizes the approaches and catalytic properties reported to date for these systems. The most recent constructs operate in neutral water and in air with the rates of H₂ production exceeding those of the hydrogenases.

Abstract

Reviewed herein is the development of novel polymer‐supported [2Fe‐2S] catalyst systems for electrocatalytic and photocatalytic hydrogen evolution reactions. [FeFe] hydrogenases are the best known naturally occurring metalloenzymes for hydrogen generation, and small‐molecule, [2Fe‐2S]‐containing mimetics of the active site (H‐cluster) of these metalloenzymes have been synthesized for years. These small [2Fe‐2S] complexes have not yet reached the same capacity as that of enzymes for hydrogen production. Recently, modern polymer chemistry has been utilized to construct an outer coordination sphere around the [2Fe‐2S] clusters to provide site isolation, water solubility, and improved catalytic activity. In this review, the various macromolecular motifs and the catalytic properties of these polymer‐supported [2Fe‐2S] materials are surveyed. The most recent catalysts that incorporate a single [2Fe‐2S] complex, termed single‐site [2Fe‐2S] metallopolymers, exhibit superior activity for H₂ production.