Palladium nanoparticles on β-cyclodextrin functionalised graphene nanosheets: a supramolecular based heterogeneous catalyst for C–C coupling reactions under green reaction conditions

Abstract

The use of functional properties of native cyclodextrins in palladium nanoparticle-b-cyclodextringraphene nanosheet (Pd@CD-GNS) catalyzed carbon-carbon (C-C) coupling reactions have been investigated under green reaction conditions. The supramolecular catalyst was prepared by deposition of Pd nanoparticles (Pd NPs) on CD-GNS using ethanol as the greener solvent and in situ reducing agent. The catalyst was characterised by FTIR, XRD, RAMAN, UV-Vis spectroscopy, TEM, SAED, XPS and ICP-AES. The catalytic activity of these catalysts is investigated in C-C coupling reactions such as Suzuki-Miyaura and Heck-Mizoroki reactions of aryl bromides and aryl chlorides containing functional groups under green reaction conditions i.e. in water, under phosphine free and aerobic conditions. This catalyst afforded excellent selectivities for the products in good to excellent yields under low Pd loadings (0.2-0.05 mol%), while ensuring the recovery and reusability of the catalysts. The reused catalyst was characterized by FTIR, TEM, XPS and ICP-AES. The CD supramolecular mediators loaded on GNS act as stabilising agents for the Pd NPs. The excellent catalytic activity of this system was attributed to the presence of CDs, excellent dispersibility in water, hydrophobic nature of the GNS support for the accumulation of organic substrates in water, "Breslow effect", the presence of PTC to overcome the mass transfer limitation onto the surface of GNS and formation of ternary CD/substrate/additive complexes on the Pd-GNS surface.

A novel magnetic NiFe2O4@graphene–Pd multifunctional nanocomposite for practical catalytic application

“…[1][2][3][4][5][6][7][8] In particular noble metal (Au, Pt and Pd) catalysts loaded on GN or functionalized GN based materials have exhibited enhanced activity and stability. [1][2][3][4][5][6][7][8] In particular noble metal (Au, Pt and Pd) catalysts loaded on GN or functionalized GN based materials have exhibited enhanced activity and stability.…”

A new strategy to design a graphene oxide supported palladium complex as a new heterogeneous nanocatalyst and application in carbon–carbon and carbon‐heteroatom cross‐coupling reactions

“…Conversion of PdCl 2 to Pd NPs using EtOH as reducing agent has been well documented and recognized . In this regard, the synthesis of the Pd(0) catalyst was initially monitored by UV–Visible spectroscopy (Figure ).…”

Immobilized Palladium Nanoparticles on Zirconium Carboxy-Aminophosphonates Nanosheets as an Efficient Recoverable Heterogeneous Catalyst for Suzuki–Miyaura and Heck Coupling

“…However, the stability and durable catalytic efficiency of nanoparticles, which are very much related to the avoidance of their aggregation and/or their minimal metal leaching in the reaction products, are still a challenge [10,11]. A large number of supports have been used to stabilize the PdNPs, such as carbon materials [12][13][14], inorganic materials [15,16], MOFs [17,18], hybrid materials [19][20][21][22][23][24] and organic polymers [25][26][27].…”

“…Besides, layered materials with a high surface area and a large amount of exposed active sites have a great potential in the development of new hybrid materials able to efficiently host palladium nanoparticles [19,20,28].…”

“…Functionalization of the support surface with appropriate functional groups represents a key approach to obtain a better control of the dimensions, dispersion and stability of NPs [20,[22][23][24][25].…”