One-pot synthesis of Hantzsch dihydropyridines using a highly efficient and stable PdRuNi@GO catalyst
Authors: Tuna Demirci
Betül Çelik
Yunus Yıldız
Sinan Eriş
Mustafa Arslan
Fatih Sen
Benan Kilbas
Journal: RSC Advances (2016)
Discipline: CHEMISTRY
Keywords: PdRuNi nanoparticles; graphene oxide; heterogeneous catalysts; 1,4-dihydropyridine synthesis; multicomponent condensation reactions
Affiliations: Scientific and Technological Research Laboratory, Duzce University, Konuralp Campus, Duzce, Turkey, Sen Research Group, Biochemistry Department, Faculty of Arts and Science, Dumlupınar University, Evliya Çelebi Campus, Chemistry Department, Faculty of Arts and Sciences, Sakarya University, Esentepe Campus, Serdivan, Department of Chemistry, Faculty of Sciences, 81620 Duzce

Abstract: Addressed herein, highly monodispersed PdRuNi nanoparticles furnished with graphene oxide (PdRuNi@GO NPs) were prepared as novel, stable, efficient and exceptionally reusable heterogeneous catalysts for 1,4-dihydropyridine synthesis via multicomponent condensation reactions of various aldehydes with dimedone, ammonium acetate and ethyl acetoacetate at 70 °C in DMF with efficient catalytic performance. These synthesized novel materials were characterized by transmission electron microscopy (TEM), high resolution electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). This presented one pot catalytic process is described as a new methodology of the Hantzsch synthesis, which can be assessed as quite simple and efficient as well as exceptionally reusable. At the end of the reaction, one of the highest yields and the shortest times were obtained for the model reaction in the presence of novel monodisperse PdRuNi@GO NPs.

Retracted: Yes

PubPeer comments:
 Type 1 histogram for particle size. ![file] Type 1 histogram found in many papers from the same group published until 2020 in variety of designs, different x-scale (size of particles) and the same relative height of bars. https: pubpeer.com publications 9331C845F0A05BF766617EFBB1AB00#2 https: pubpeer.com publications F5517C2786C02B2C34E63266AC642A , 
 Figure 3. X-ray photoelectron spectra of Ru 3p in PdRuNi@GO nanocomposites in this paper is the same as in 2017 paper doi: 10.1016 j.nanoso.2017.08.013 Figure 2: XPS spectra of PdRu@GO ![file] , 
 XPS for Pd is also the same (except for color) in these two papers: https: pubpeer.com publications 7A123B2F1443D6AC355E4B633E05E2#3 ![file] , 
 Figure 3 Ni 2p XPS spectra of PdRuNi@GO can be found (with more beautiful colors) in another paper for Ni@f-MWCNT ![file] http: dx.doi.org 10.1016 j.bios.2017.01.045 https: pubpeer.com publications BA11ED6001BA118003C86808EA9905 , 
 XPS Pd 3d spectrum is found also in Scientific Reports 2019 paper representing there PdNi@rGO. The spectrum shown in 3D picture but also in standard 2D view which is more easy to compare. ![file] Ru is gone and GO is reduced in 2019 study but Pd 3d spectrum keeps the same noise. https: pubpeer.com publications 6389B57905710C7A5B59C6673547D7 , 
 Three more occasions of publication the same Ru XPS spectra: ![file] , 
 Retraction, October 2021: https: pubs.rsc.org en content articlelanding 2021 ra d1ra90151f  The Royal Society of Chemistry hereby wholly retracts this RSC Advances article due to concerns with the reliability of the data in the published article. The particle size histogram of PdRuNi@GO NPs in Fig. 2c has the same relative bar heights as particle size histograms in at least six other papers by the same authors, all representing different nanoparticles or synthetic methods. The authors provided replacement data for consideration. However, an expert reviewed the authorsu2019 response and concluded that it did not satisfactorily address the concerns, and that the replacement figure did not fully support the conclusions. The 2D Pd3d XPS spectra for PdRuNi@GO nanoparticles in Fig. 3a was later published by the authors in Scientific Reports in Fig. 2d to represent PdNi@rGO.1 The 3D Pd3d XPS spectra for PdRuNi@GO nanoparticles in Fig. 3a was later published by the authors in Nano-Structures Nano-Objects in Fig. 2a to represent PdRu@GO nanocomposites.2 The 3D Ru3p XPS spectra for PdRuNi@GO nanoparticles in Fig. 3b was later published by the authors in Nano-Structures Nano-Objects in Fig. 2b to represent PdRu@GO nanocomposites,2 in the Journal of Molecular Liquids in Fig. 3b to represent Ru(0) graphite NPs,3 in Nanocarbon and its Composites in Fig. 3b to represent Ru PVP@C4 and previously by the authors in Chemistry Select in Fig. 3b to represent RuPd@GO NPs.5 The 3D Ni2p XPS spectra for PdRuNi@GO nanoparticles in Fig. 3b was later published by the authors in Biosensors Bioelectronics in Fig. 2b to represent Ni@f-MWCNT.6 The authors claim that the XPS spectra in Fig. 3 were included in error and provided replacement data for consideration. However, an expert reviewed the authoru2019s response and concluded that it did not satisfactorily address the concerns, and that the replacement figure did not fully support the conclusions. Given the significance of the concerns about the validity of the data, the findings presented in this paper are no longer reliable. Sinan Eriu015f, Tuna Demirci, Mustafa Arslan, Benan Kilbas and Fatih Sen oppose this retraction. Betu00fcl u00c7elik and Yunus Yu0131ldu0131z were contacted but did not respond. Signed: Laura Fisher, Executive Editor, RSC Advances Date: 23rd September 2021 ,