Modification of palladium–copper thin film by reduced graphene oxide or platinum as catalyst for Suzuki–Miyaura reactions

This study describes the synthesis of PdCu, PdCu/reduced graphene oxide and PtPdCu nanoparticle thin films via a simple reduction of organometallic precursors including [PtCl₂(cod)] and [PdCl₂(cod)] (cod = cis ,cis ‐1,5‐cyclooctadiene) complexes, in the presence of [Cu(acac)₂] (acac = acetylacetonate) complex at toluene–water interface. The structure and morphology of the thin films were characterized using energy‐dispersive analysis of X‐rays, X‐ray diffraction and transmission electron microscopy techniques. Our studies show that all of these nanoparticles are suitable for the Suzuki–Miyaura coupling (SMC) reaction in water. PtPdCu and PdCu thin films showed higher catalytic activity compared to Pd thin film in the SMC reaction due to the appropriate interaction among palladium, platinum and copper metals.     

Dithienylmethanone‐Based Cross‐Conjugated Polymer Semiconductors: Synthesis,Characterization, and Application in Field‐Effect Transistors

Herein, we report the synthesis, characterization, and field‐effect properties of two cross‐conjugated dithienylmethanone (DMO)‐based alternating polymers, namely, PDMO‐S and PDMO‐Se . Both polymers possess high thermal stability, good solubility, and broad absorption spectra. Their electrochemical properties were investigated using cyclic voltammetry, indicating that PDMO‐Se has higher HOMO/LUMO energy levels of −5.49/−3.49 eV than −5.57/−3.58 eV of PDMO‐S . The two polymers exhibited promising charge transport properties with the highest hole mobility of 0.12 cm² V⁻¹ s⁻¹ for PDMO‐S and 0.025 cm² V⁻¹ s⁻¹ for PDMO‐Se . AFM and 2D‐GIXRD analyses demonstrated that the PDMO‐S formed lamellar, edge‐on packing thin film with close π‐π stacking. These findings suggest that cross‐conjugated polymers might be potential semiconducting materials for low‐cost and flexible organic electronics. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1012–1019     

An even earlier (1717) usage of the expression “golden section”

In a previous article in this journal, Roger Herz-Fischler has pointed out an early usage of the expression “golden section” from 1789. In this note an even earlier usage from 1717 is discussed.     

Palladium on magnetic Irish moss: A new nano‐biocatalyst for suzuki type cross‐coupling reactions

A novel heterogeneous magnetic palladium nano‐biocatalyst was designed by utilizing Irish moss, a family of sulfated polysaccharides extracted from algae, as a natural biopolymer. This magnetic Irish moss decorated with palladium (Pd–Fe₃O₄@IM) to form a biomagnetic catalytic system was synthesized and well characterized by FT–IR analysis, X‐ray powder diffraction, field emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, atomic absorption spectroscopy and transmission electron microscopy. The catalyst was stable to air and moisture and displayed high catalytic activity in ligand‐free Suzuki–Miyaura cross‐coupling reactions conducted under green chemistry reaction conditions. The aromatic ketones are produced by the cross‐coupling reaction between acid chlorides and aryl boronic acid derivatives in high yields.     

Finely dispersed palladium on silk‐fibroin as an efficient and ligand‐free catalyst for Heck cross‐coupling reaction

A palladium–fibroin complex (Pd/Fib.) was prepared by the addition of sonicated fibroin fiber in water to palladium acetate solution. Pd (OAc)₂ was absorbed by fibroin and reduced with NaBH₄ at room temperature to the Pd(0) nanoparticles. Powder‐X‐ray diffraction, scanning electron microscopy–energy‐dispersive X‐ray spectroscopy, Fourier transform‐infrared, CHN elemental analysis and inductively coupled plasma‐atomic emission spectroscopy were carried out to characterize the Pd/Fib. catalyst. Catalytic activity of this finely dispersed palladium was examined in the Heck coupling reaction. The catalytic coupling of aryl halides (‐Cl, ‐Br, ‐I) and olefins led to the formation of the corresponding coupled products in moderate to high yields under air atmosphere. A variety of substrates, including electron‐rich and electron‐poor aryl halides, were converted smoothly to the targeted products in simple procedure. Heterogeneous supported Pd catalyst can be recycled and reused several times.     

C‐S cross‐coupling reaction using novel and green synthesized CuO nanoparticles assisted by Euphorbia maculata extract

In the present study, biosynthesis of CuO nanoparticles using a rapid, eco‐friendly, cost‐effective and efficient method has been reported employing aqueous Euphorbia maculata extract as mild, renewable and non‐toxic reducing and capping agents without adding any surfactants. The biogenic and green method has some benefits compared to conventional physical and chemical methods. It is simple, cheap and environmentally friendly. The biosynthesized CuO NP displayed a color change pattern (from sky blue to black) on preparation and presented its respective broad peak at 365 nm, which was analyzed by UV–Vis spectroscopy. Using the FT‐IR analysis, biomolecules in E. maculata extract which are responsible for bioreduction activity and synthesize of CuO NP, were identified. The XRD, EDX and FESEM results confirmed the successful synthesis of CuO nanoparticles of 18 nm sizes, with spherical and sponge crystal structure. The catalytic activity of biosynthesized CuO NPs was studied in C‐S cross‐coupling reaction. This method has the advantages of high yields, easy work‐up, and simple reusability. The recovered CuO NP can be reused four times without any considerable loss of its catalytic activity.