Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

• his research group developed a novel sulfonic graphitic carbon nitride (g-C3N4-SO3H) as a nanosheet ionic liquid for the one-pot synthesis of BIMs [125]. Graphitic carbon nitride is a non-metal and non-toxic chemically stable nanostructure, which is obtained through a facile pyrolysis process that has

Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor

• Pengcheng Li,
• Daniel Kowalczyk,
• Johannes Liessem,
• Mohamed M. Elnagar,
• Dariusz Mitoraj,
• Radim Beranek and
• Dirk Ziegenbalg

Beilstein J. Org. Chem. 2024, 20, 74–91, doi:10.3762/bjoc.20.9

• evolution using a Pt-loaded polymeric carbon nitride photocatalyst under 365 nm irradiation in the presence of sacrificial reducing agents. The fluid flow pattern of the developed photoreactor was characterized experimentally and the photon flux incident to the loop photoreactor was measured by chemical

• Pt-loaded polymeric carbon nitride (Pt-PCN) powder using methanol as sacrificial agent (Scheme 1) is studied as a benchmark in the designed loop photoreactor. Four parameters, namely photon flux, photocatalyst loading, stirring speed, and inert gas flow rate, are investigated for their effect on the

• photocatalytic hydrogen evolution using Pt loaded polymeric carbon nitride in a 21 mL Schlenk tube (AQE = 0.06%) [30]. The maximum hydrogen generation rate observed was 460.66 µmol h−1 at a photon flux of 32.77 µmol s−1, a catalyst loading of 0.22 g L−1, a stirring speed of 560 rpm and an inert gas flow rate of

Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water

• Lorenzo Catti,
• Shinji Aoyama and
• Michito Yoshizawa

Beilstein J. Org. Chem. 2024, 20, 32–40, doi:10.3762/bjoc.20.5

• ., graphitic carbon nitride) in the form of 10–30 nm-sized stacks is also demonstrated using the present amphiphiles. Keywords: aromatic micelle; nanocarbon; nonionic surface modification; pyridinium; water-solubilization; Introduction Nanocarbons, such as fullerenes, graphenes, and carbon nanotubes, are

• pyridinium-based amphiphiles (Figure 1c). The noncovalent modification of C60 with multiple imidazole side-chains is found to yield a pH-responsive surface charge, as evidenced by NMR and zeta-potential measurements. A nitrogen-doped nanocarbon, i.e., graphitic carbon nitride (g-C3N4), is likewise

• via their encircling by the present amphiphiles in water. For example, utilizing the imidazole-functionalized amphiphile, an aqueous fullerene-based host–guest composite with pH-responsive surface charge was generated. In addition, water-solubilization of graphitic carbon nitride and subsequent

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• -schemes are usually developed independently with different donors. Recently Ma et al. have developed a carbon dioxide reduction photosystem composed of a cobalt–quaterpyridine catalyst anchored to carbon nitride semiconductor particles [55]. Rather than an inorganic sacrificial donor, they developed this

Mechanochemical bottom-up synthesis of phosphorus-linked, heptazine-based carbon nitrides using sodium phosphide

• Blaine G. Fiss,
• Georgia Douglas,
• Michael Ferguson,
• Jorge Becerra,
• Jesus Valdez,
• Trong-On Do,
• Tomislav Friščić and
• Audrey Moores

Beilstein J. Org. Chem. 2022, 18, 1203–1209, doi:10.3762/bjoc.18.125

• -PCN300) show a reduction in photoluminescent recombination, as well as a nearly two-time increase in photocurrent under broad spectrum irradiation, which are appealing properties for photocatalysis. Keywords: carbon nitride; density functional theory; mechanochemistry; phosphorus; photochemistry

• , examples of carbon nitride materials linked together via phosphorus atoms are limited, likely due to challenges in controlling the insertion of phosphorus atoms as linkers under high energy conditions. Mechanochemistry [9][10][11][12] has proven to be effective for the synthesis of a variety of polymers

• explored herein the use of solvent-free, room temperature mechanochemistry to access phosphorus-linked carbon nitride with repeating heptazine units, which were found to show improved photochemistry over pristine graphitic carbon nitride (g-CN). Additionally, the effect of a 1-hour annealing period at 300

Photoredox catalysis in nickel-catalyzed C–H functionalization

• Lusina Mantry,
• Rajaram Maayuri,
• Vikash Kumar and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

• carbon nitride (mpg-CN) [74][75][76] as a heterogeneous organic semiconductor photocatalyst in combination with nickel catalysis [77]. Here, the catalytic system consisting of NiBr2·glyme, 2,2′-bipyridine, 2,6-lutidine, and mpg-CN under blue light irradiation at ambient temperature was found to be

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• has been selectively feasible without activating a C(sp2)–H bond in the arene moiety. Verma and co-workers [91] have reported the use of VO(acac)2 immobilized over graphitic carbon nitride (VO@gC3N4) under visible light irradiation to perform a photocatalytic C–H activation of arene methides and

Photoinduced post-modification of graphitic carbon nitride-embedded hydrogels: synthesis of 'hydrophobic hydrogels' and pore substructuring

• Cansu Esen and
• Baris Kumru

Beilstein J. Org. Chem. 2021, 17, 1323–1334, doi:10.3762/bjoc.17.92

• novelty. Here, a metal-free semiconductor graphitic carbon nitride (g-CN)-embedded hydrogel as an initial network was synthesized via redox-couple initiation under dark conditions. Post-photomodification of so-formed hydrogel, thanks to the photoactivity of the embedded g-CN nanosheets, was exemplified in

• -sustainable semiconductors are slowly being replaced by a new generation of semiconductors. Graphitic carbon nitride (g-CN) is a metal-free polymeric semiconductor that is mainly composed of carbon and nitrogen elements by tri-s-triazine, triazine imide, or heptazine repeating units [16][17][18]. g-CN

• of this study, which is divided into two parts, the hydrogel denoted as HGCM was utilized as the main substrate for both sections. To prepare HGCM, firstly graphitic carbon nitride was synthesized from the thermal treatment of a cyanuric acid–melamine supramolecular complex (CM) [42]. The resulting

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Heterogeneous photocatalytic cyanomethylarylation of alkenes with acetonitrile: synthesis of diverse nitrogenous heterocyclic compounds

• Guanglong Pan,
• Qian Yang,
• Wentao Wang,
• Yurong Tang and
• Yunfei Cai

Beilstein J. Org. Chem. 2021, 17, 1171–1180, doi:10.3762/bjoc.17.89

• .17.89 Abstract A visible light-mediated heterogeneous photocatalytic cyanomethylarylation of alkenes with acetonitrile has been established using K-modified carbon nitride (CN-K) as a recyclable semiconductor photocatalyst. This protocol, employing readily accessible alkyl N-hydroxyphthalimide (NHPI

• ) ester as a radical initiator, allows the efficient construction of a broad array of structural diverse nitrogenous heterocyclic compounds including indolines, oxindoles, isoquinolinones, and isoquinolinediones. Keywords: carbon nitride; cyanoalkylarylation; heterocyclic compound; heterogeneous

• conditions. Recently, we demonstrated K-modified carbon nitride (CN-K), a semiconductor material, exhibited a remarkably enhanced photocatalytic activity in the decarboxylative Giese reaction. The effect was due to its K-intercalated poly(heptazine)-based structure existing as small lamellar nanocrystallites

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• dependent on the temperature and electronic disorder as each hop requires the reorganisation of the molecules in the chain [115]. A particularly popular organic semiconductor photocatalyst in the recent literature is graphitic carbon nitride (g-C3N4) [23]. g-C3N4 was one of the first synthetic polymers

• carriers) occurs over 200 femtoseconds. The resulting polarons migrate by “hopping” between the sheets until they eventually recombine over a period of approximately 10−13–10−6 s (Figure 10) [107]. Mesoporous graphitic carbon nitride (mpg-C3N4) has recently been reported by Antonietti, König, and co

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• thermal decomposition of urea at 550 °C for 2 h afforded the CN polymer, which possesses abundant –NH2 functional groups. The heterogeneous photocatalyst carbon nitride-hemin (CNH) was prepared after an amidation reaction between a carboxyl group of Fe(III) protoporphyrin IX and an amino group of the CN

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• products substituted at the 1- and 4-position in good to high yields and with short reaction times (Scheme 17). The nanocatalyst GO@polytriazole–Cu (85) could easily be recovered from the reaction mixture and was reused in five cycles, with no decline of its performance. The design and synthesis of carbon

• nitride-supported copper nanoparticles was disclosed by Islam and co-workers (Scheme 18) [79][80]. The nanocatalyst 87 was successfully used as a high-performance photoreactor promoting “click” reactions of alkynes with organic azides under light irradiation in the absence of basic condition. In the first

Bioinspired cobalt cubanes with tunable redox potentials for photocatalytic water oxidation and CO₂ reduction

• Zhishan Luo,
• Yidong Hou,
• Jinshui Zhang,
• Sibo Wang and
• Xinchen Wang

Beilstein J. Org. Chem. 2018, 14, 2331–2339, doi:10.3762/bjoc.14.208

• photocatalytic conversions has been the Achilles’ heel of solar energy utilization. Here, we report on a chemical approach based on ligand designed architectures to fabricate unique structural molecular catalysts coupled with appropriate light harvesters (e.g., carbon nitride and Ru(bpy)32+) for photoredox

• O2 gas and CO2-to-CO conversion (Figure 5). For the water oxidation, we have chosen carbon nitride [56][57][58][59][60] coupled with the 1-R molecular complexes to evaluate the oxygen evolution performance. In Figure 5a, without the 1-R molecular complexes, the O2 production rate is rather low (1.2

• deposition of Ag particles on the surface of polymeric carbon nitride (p-C3N4, PCN), which leads to a light shading effect hindering optical absorption. In the stability test for CO2 reduction reactions, no noticeable losses in the yields of CO and H2 were observed in 4 cycles (Figure 5d). The deactivation

Graphitic carbon nitride prepared from urea as a photocatalyst for visible-light carbon dioxide reduction with the aid of a mononuclear ruthenium(II) complex

• Kazuhiko Maeda,
• Daehyeon An,
• Ryo Kuriki,
• Daling Lu and
• Osamu Ishitani

Beilstein J. Org. Chem. 2018, 14, 1806–1812, doi:10.3762/bjoc.14.153

• -ku, Tokyo 102-0083, Japan Suzukakedai Materials Analysis Division, Technical Department, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan 10.3762/bjoc.14.153 Abstract Graphitic carbon nitride (g-C3N4) was synthesized by heating urea at different temperatures

• phase. Keywords: artificial photosynthesis; heterogeneous photocatalysis; hybrid material; metal complexes; solar fuels; Introduction Carbon nitride is one of the oldest synthetic polymers [1], and has several allotropes. Among them, graphitic carbon nitride (g-C3N4) is the most stable form and is an

Fluorogenic PNA probes

• Tirayut Vilaivan

Beilstein J. Org. Chem. 2018, 14, 253–281, doi:10.3762/bjoc.14.17

• restoration of the fluorescence in pretty much the same way as GO. Likewise, carbon nitride nanosheets [148] and a zirconium-based nano metal-organic framework (UiO-66) [149] behaved similarly. In addition, they have been successfully used in combination with PNA for monitoring of miRNA inside living cells

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• sulfinate salts afforded moderate to high yields of the respective products. In this study, we could also exclude a reductive quenching cycle by transient spectroscopy. Very recently a heterogeneous modified carbon nitride photocatalyst could successfully be applied to the synthesis of vinyl sulfones

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF₃SO₂Cl

• Hélène Chachignon,
• Hélène Guyon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2800–2818, doi:10.3762/bjoc.13.273

• -workers thereafter reported that the trifluoromethylation of (hetero)arenes could also be performed under heterogeneous catalysis [33]. To this aim, the Ru- or Ir-based catalysts were replaced with a mesoporous graphitic carbon nitride polymer (mpg-CN), which offers the advantage of being cheap, metal

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

• Carmen Moreno-Marrodan,
• Francesca Liguori and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2017, 13, 734–754, doi:10.3762/bjoc.13.73

• a mesoporous polymeric graphitic carbon nitride (mpg-C3N4, Figure 4a) [122]. The catalyst showed the highest productivity in the series (13.3 mol1a gPd−1 h−1), under fairly mild conditions (343 K, 5 bar H2) (Table 1, entry 6), which was attributed to the facile hydrogen activation and alkyne

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• noting that the developed protocol could be easily applied to the synthesis of anilines and aryl thiols. In 2014, the Jiang and Han group used a copper-doped graphitic carbon nitride catalyst Cu-g-C3N4, which was prepared from urea and CuNO3, and developed a ligand free protocol for the synthesis of

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• years the development of new and effective nanostructured catalytic systems dominated the gold-catalyzed approach to A3-coupling. For example, ultrasmall gold(0) nanoparticles embedded in a mesoporous carbon nitride stabilizer [27] proved to be a highly active, selective and recyclable heterogeneous

Metal-free aerobic oxidations mediated by N-hydroxyphthalimide. A concise review

• Lucio Melone and
• Carlo Punta

Beilstein J. Org. Chem. 2013, 9, 1296–1310, doi:10.3762/bjoc.9.146

• the photocatalytic oxidative activation of NHPI by graphitic carbon nitride (g-C3N4) and visible light irradiation [65]. g-C3N4, the most stable allotrope of carbon nitride, is a two-dimensional polymer with a tri-s-triazine ring unit and a π-conjugated layered structure similar to graphene. It is a

NHC-catalysed highly selective aerobic oxidation of nonactivated aldehydes

• Lennart Möhlmann,
• Stefan Ludwig and
• Siegfried Blechert

Beilstein J. Org. Chem. 2013, 9, 602–607, doi:10.3762/bjoc.9.65

• of carbinols to aldehydes or ketones using oxygen, visible light and mesoporous graphitic carbon nitride (mpg-C3N4) polymer as a metal-free photocatalyst [4]. As an extension of this method we were interested in a consecutive organocatalytic process using an N-heterocyclic carbene (NHC) together with