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Direct synthesis of N‐containing organic compounds from dinitrogen (N2) can make synthetic chemistry more sustainable. Previous bottlenecks in lithium‐mediated N2 fixation were resolved by loading Li‐metal anodes covered with the typical Li+ ion‐conducting solid electrolyte interface, which are subsequently allowed to react with N2. The developed strategy allowed us to reach high Faradaic efficiencies toward Li3N. These reactive Li3N were then contacted with acylchlorides. Surface nitride ions are more nucleophilic than amines which direct the two C−N coupling reactions toward formation of imides rather than amides, and an integrated current efficiency of 57–77 % could be realized. This study thereby not only provides a feasible electrochemical Li3N synthesis, but also delineates an economical and green synthesis of highly valuable N‐containing compounds from N2 under mild conditions, just using commercial spare parts and processes from the omnipresent Li battery technology. [ABSTRACT FROM AUTHOR]

The development of novel chemical transformations calls for environmentally friendly synthetic methods. Visible light photoredox catalysis has gained attention as a versatile tool to address these challenges. Due to the well‐defined structure of homogeneous transition metal‐based catalysts and organic dyes, they have been widely used to drive a wide variety of organic transformations. On the other hand, due to low cost, simple preparation procedure, and chemical stability of carbon nitride semiconductors, they have been known almost exclusively in environmental applications and water splitting. Until recently the applicability of carbon nitride semiconductors in organic synthesis has remained hidden from the broad community of organic chemists. In this review, we summarize reactions mediated by heterogeneous carbon nitride photocatalysts and common homogeneous photocatalysts in the same organic reactions, such as carbon‐carbon or carbon‐heteroatom bond formation reactions. We compare performance of both groups of catalysts in the discussed organic reactions. [ABSTRACT FROM AUTHOR]

Direct synthesis of N-containing organic compounds from dinitrogen (N 2 ) can make synthetic chemistry more sustainable. Previous bottlenecks in lithium-mediated N 2 fixation were resolved by loading Li-metal anodes covered with the typical Li + ion-conducting solid electrolyte interface, which are subsequently allowed to react with N 2 . The developed strategy allowed us to reach high Faradaic efficiencies toward Li 3 N. These reactive Li 3 N were then contacted with acylchlorides. Surface nitride ions are more nucleophilic than amines which direct the two C-N coupling reactions toward formation of imides rather than amides, and an integrated current efficiency of 57-77 % could be realized. This study thereby not only provides a feasible electrochemical Li 3 N synthesis, but also delineates an economical and green synthesis of highly valuable N-containing compounds from N 2 under mild conditions, just using commercial spare parts and processes from the omnipresent Li battery technology., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Among external stimuli used to promote a chemical reaction, photocatalysis possesses a unique one-light. Photons are traceless reagents that provide an exclusive opportunity to alter chemoselectivity of the photocatalytic reaction varying the color of incident light. This strategy may be implemented by using a sensitizer capable to activate a specific reaction pathway depending on the excitation light. Herein, we use potassium poly(heptazine imide) (K-PHI), a type of carbon nitride, to generate selectively three different products from S-arylthioacetates simply varying the excitation light and otherwise identical conditions. Namely, arylchlorides are produced under UV/purple, sulfonyl chlorides with blue/white, and diaryldisulfides at green to red light. A combination of the negatively charged polyanion, highly positive potential of the valence band, presence of intraband states, ability to sensitize singlet oxygen, and multi-electron transfer is shown to enable this chromoselective conversion of thioacetates., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

In photocatalysis, small organic molecules are converted into desired products using light responsive materials, electromagnetic radiation, and electron mediators. Substitution of low molecular weight reagents with redox active functional materials may increase the utility of photocatalysis beyond organic synthesis and environmental applications. Guided by the general principles of photocatalysis, we design hybrid nanocomposites composed of n-type semiconducting potassium poly(heptazine imide) (K-PHI), and p-type conducting poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as the redox active substrate. Electrical conductivity of the hybrid nanocomposite, possessing optimal K-PHI content, is reversibly modulated combining a series of external stimuli ranging from visible light under inert conditions and to dark conditions under an O 2 atmosphere. Using a conductive polymer as the redox active substrate allows study of the photocatalytic processes mediated by semiconducting photocatalysts through electrical conductivity measurements., (© 2020 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

A sunlight-powered process is reported that employs carbon dots (CDs) as light absorbers for the conversion of lignocellulose into sustainable H 2 fuel and organics. This photocatalytic system operates in pure and untreated sea water at benign pH (2-8) and ambient temperature and pressure. The CDs can be produced in a scalable synthesis directly from biomass itself and their solubility allows for good interactions with the insoluble biomass substrates. They also display excellent photophysical properties with a high fraction of long-lived charge carriers and the availability of a reductive and an oxidative quenching pathway. The presented CD-based biomass photoconversion system opens new avenues for sustainable, practical, and renewable fuel production through biomass valorization., (© 2020 The Authors. Published by Wiley-VCH GmbH.)

Polymeric carbon nitride materials have been used in numerous light-to-energy conversion applications ranging from photocatalysis to optoelectronics. For a new application and modelling, we first refined the crystal structure of potassium poly(heptazine imide) (K-PHI)-a benchmark carbon nitride material in photocatalysis-by means of X-ray powder diffraction and transmission electron microscopy. Using the crystal structure of K-PHI, periodic DFT calculations were performed to calculate the density-of-states (DOS) and localize intra band states (IBS). IBS were found to be responsible for the enhanced K-PHI absorption in the near IR region, to serve as electron traps, and to be useful in energy transfer reactions. Once excited with visible light, carbon nitrides, in addition to the direct recombination, can also undergo singlet-triplet intersystem crossing. We utilized the K-PHI centered triplet excited states to trigger a cascade of energy transfer reactions and, in turn, to sensitize, for example, singlet oxygen ( 1 O 2 ) as a starting point to synthesis up to 25 different N-rich heterocycles., (© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)