A rapid and novel method for the synthesis of 5-substituted 1H-tetrazole catalyzed by exceptional reusable monodisperse Pt NPs@AC under the microwave irradiation
Authors: Esma Erken
İbrahim Esirden
Muharrem Kaya
Fatih Sen
Journal: RSC Advances (2015)
Discipline: CHEMISTRY
Keywords: 1H-tetrazoles; microwave irradiation; catalyst; platinum nanoparticles; activated carbon
Affiliations: Biochemistry Department, Faculty of Arts and Science, Dumlupınar University, 43100 Kütahya, Turkey, Chemistry Department

Abstract: A series of 5-substituted 1H-tetrazoles were synthesized in DMF by the [3 + 2] cycloaddition reaction under the effect of microwave irradiation (10–30 min, fixed mode, 90 °C, 140 W) in the presence of highly efficient superior catalyst. For this reaction, different aromatic nitriles with the sodium azide were used and superior monodisperse (Md) platinum nanoparticles (Pt NPs) decorated on activated carbon (AC) served as a catalyst. Md-Pt NPs@AC were reproducibly and easily produced by double solvent reduction of PtCl4 in room temperature and characterized by transmission electron microscopy (TEM), the high resolution electron micrograph (HRTEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The sum of their results shows the formation of highly crystalline and colloidally stable Md-Pt NPs@AC. The catalytic performance of these new NPs were investigated for the synthesis of 5-substituted 1H-tetrazoles, in which they were found to be exceptional reusable, isolable, stable and highly efficient heterogeneous catalyst. All prepared tetrazole products were obtained with perfect yield by using current heterogeneous catalyst and characterized by melting points, FT-IR, 1H-NMR, 13C-NMR and HRMS analyzes.

Retracted: Yes

PubPeer comments:
 This paper appears to be one of a set of at least 2 papers by the same research group that both appear to share the same photo. In both papers, this photo is used as a zoomed-in inset representing the high-resolution transmission electron microscopy (HRTEM) analysis of the  atomic lattice fringe and particle size of the nanoparticles. Of concern, the same photo, which I have called  Inset 5 , is used to represent a different type of nanoparticle in each of these papers. The two papers using the  Inset 5 photo are: * Esma Erken et al. - DOI: 10.1039 C5RA11426H - MdPt@AC * Haydar Gou0308ksu et al. - DOI: 10.1002 slct.201600509 - CoPd@CNT Here is a comparison of both figures that contain the  Inset 5 photo: ![file] ![file] Here is a close-up view of both inset photos with green boxes marking the similar-looking areas. The red and white lines are part of the original photos. ![file] Of note, this is a different set of papers than the 30 papers by the same group that all appear to use another HRTEM image called  Inset 1 . For an example of that photo and the list of those 30 papers, see DOI 10.1016 j.ijhydene.2018.03.175 https: pubpeer.com publications 8AD71F4A32472314CCE9983D47E36F It is also a different set of papers than the 14 papers by the same group that all appear to use another HRTEM image called  Inset 2 . For an example of that photo and the list of those 14 papers, see DOI: 10.1016 j.ijhydene.2017.05.113 https: pubpeer.com publications CAD2F16435F6C639F5DE6851A2E61D , 
 Retraction, October 2021: https: pubs.rsc.org en content articlelanding 2021 ra d1ra90149d  Muharrem Kaya and u0130brahim Esirden hereby wholly retract this RSC Advances article due to concerns with the reliability of the data in the published article. The high-resolution transmission electron micrograph inset in Fig. 2 that represents Md-Pt NPs@AC is the same as Fig. 2c in a Chemistry Select article by Haydar Gu00f6ksu, Betu00fcl u00c7elik, Yunus Yu0131ldu0131z, Fatih u015een and Benan Ku0131lbau015f,1 which is a high-resolution transmission electron micrograph representing a CoPd NP. Fatih Sen 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. Muharrem Kaya approves the retraction of this article due to concerns with the structural characterisation of the catalyst and therefore the conclusions presented may not be valid. Muharrem Kaya also states that the figures under question are out of their expertise and that they did not contribute to the data collection or processing of these figures. Muharrem Kaya contributed to the evaluation of the catalytic performances of the composite materials only. Fatih Sen opposes this retraction. Esma Erken was contacted but did not respond. Signed: Muharrem Kaya and u0130brahim Esirden Date: 23rd September 2021 Retraction endorsed by Laura Fisher, Executive Editor, RSC Advances ,