Fabrication of Graphitic Carbon Nitride‐Based Film: An Emerged Highly Efficient Catalyst for Direct C—H Arylation under Solar Light

Abstract

Main observation and conclusion Photoredox C—H bond formation can proceed in aerobic environment under solar light and has therefore become attractive. Nowadays, different types of expensive novel metal complexes and nanomaterials have been urbanized as photocatalysts for direct C—H bond formation in between derivatives of heteroarenes (HAs) and aryl diazonium salts. These photocatalysts, however, still suffer from poor stability, high cost, and decay. Herein, a graphitic carbon nitride‐based fluorescein isothiocyanate (g‐C3N4–FITC) film photocatalyst has been reported, which shows excellent light harvesting ability, and band gap suitability to catalyze the metal free direct C—H arylation of HAs under solar light at ambient temperature. Moreover, the g‐C3N4–FITC film photocatalyst can be reused four times without significant loss of activity, confirming the excellent photocatalytic stability. The current strategy to construct a g‐C3N4–FITC film photocatalyst for direct C—H arylation opens a new path towards replacing metal‐based catalysts in fine chemical synthesis.

Sustainable protocols for direct C–H bond arylation of (hetero)arenes

“…109 Very recently, Yadav et al proposed a graphitic carbon nitride-based fluorescein isothiocyanate (called g-C 3 N 4 -FITC) thin film as an excellent photocatalyst for the direct arylation of furan and thiophene, which was used up to four times with no significant loss of activity. 110 These three protocols are in our opinion very appealing in the framework of Green Chemistry: in fact, the use of a recoverable and recyclable catalytic system was here coupled with the use of a photocatalytic method as non conventional energy source, aryl diazonium salts as highly environmentally friendly arylating agents (due to the formation of N 2 as by-product), and in some cases also a quite sustainable reaction medium.…”

“…Very recently, Yadav and co-workers proposed the use of a graphitic carbon nitride-based fluorescein isothiocyanate (g-C 3 N 4 -FITC) thin film as an excellent photocatalyst, having the great advantage of being active under sunlight, for the direct C-H bond arylation of furans performed in DMSO at room temperature for 6 h. 110 All the abovementioned photochemical protocols for direct C-H bond arylation of furans were actually also performed on thiophenes, in most cases with similar yields: in fact, given their similar chemical structure, photochemical processes on thiophenes were often considered as an extension of protocols first developed for furans.…”

Advances in Photocatalytic Organic Synthetic Transformations in Water and Aqueous Media

“…26,27 Metal-free photocatalytic arylations 28 have been reported with numerous photocatalysts, such as carbon nitride-based catalysts. 30 A few examples of photocatalytic arylations in aqueous media have been informed. 31 Xue and colleagues 32 have developed a photocatalytic arylation reaction of electron-deficient heteroarenes in water starting from aryldiazonium salts.…”

“…Radical arylation reactions are synthetic strategies that allow the formation of new C Ar –C Ar bonds or C aliph –C Ar bonds from aryl radicals . There are extensive studies on photocatalyzed arylation reactions. , Metal-free photocatalytic arylations have been reported with numerous photocatalysts, such as carbon nitride-based catalysts …”

In Situ Prepared NRCPFs as Highly Active Photo Platforms for in Situ Bond Formation Between Aryldiazonium Salts and Heteroarenes

“…The key to raise above the restrictions of metal-free photocatalytic routes/systems and to study the carbon (C)-hydrogen (H) bond activation in aerobic condition and mechanistic controlled pathways lies in a specific control of the highly active surface sites, which can be achieved by tumbling the carbonization at high temperature. Accordingly, we introduce here an extraordinary and formerly undisclosed important application of metal-free CMF/CPF catalysts/photocatalysts for green and eco-friendly C-H bond activation reactions (29)(30)(31). For this idea, we prepared the inexpensive 1,4dicyanobenzene (DCB) as the N and O-containing monomer for newly in situ prepared nitrogen-rich covalent perylene frameworks (NRCPFs) as highly active photo platforms via simple self-polymerization method (32).…”