IP: 5.62.159.99 On: Wed, 08 May 2019 03:05:48 Copyright: American Scientific Publishers Delivered by Ingenta Copyright © 2019 American Scientific Publishers All rights reserved Printed in the United States of America Article Journal of Nanoscience and Nanotechnology Vol. 19, 4623–4631, 2019 www.aspbs.com/jnn Nanocrystalline Cu–ZnO as an Green Catalyst for One Pot Synthesis of 4,4 ′ -((phenyl)methylene)bis(3-methyl- 1-phenyl-1H-pyrazol-5-ol) Derivatives Santosh Shinde 1 , Bhausaheb Karale 1 , Digambar Bankar 5 , Sudhir Arbuj 5 , Mansur Moulavi 5 , Dinesh Amalnerkar 3 ∗ , Taesung Kim 3 4 ∗ , and Kaluram Kanade 1 2 ∗ 1 Post Graduate Department of Chemistry, Radhabai Kale Mahila Mahavidyalaya, Ahmednagar 414001, India 2 Post Graduate Department of Chemistry, Yashwantrao Chavan Institute of Science, Satara 415001, India 3 School of Mechanical Engineering, Sungkyunkwan University (SKKU) 300, Cheoncheon-dong, Jangan-gu, Suwon, Gyeonggi, 440-746, South Korea 4 SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 440-746, South Korea 5 Centre for Materials for Electronic Technology (C-MET), Off Pashan Road, Panchwati, Pune 411008, India Synthesis of 4,4 ′ -((phenyl)methylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ol) derivatives was suc- cessively carried out using Cu doped ZnO nanomaterials. The nanocrystalline Cu–ZnO was obtained by decomposing as-synthesized copper–zinc oxalate intermediate at 520  C. The pre- pared Cu–ZnO nanostructured catalyst was characterized with FTIR, X-ray diffraction, field emis- sion scanning electron microscope and electron diffraction techniques. XRD analysis indicates the formation of highly crystalline hexagonal phase of ZnO along with the presence of monoclinic CuO. FESEM photographs shows the existence of plate like structures made up of small spheri- cal shaped particles having size in the range of 30–50 nm. As-synthesized Cu–ZnO was used as heterogeneous catalyst for one pot synthesis of 4,4 ′ -((phenyl)methylene)bis(3-methyl-1-phenyl-1H- pyrazol-5-ol) derivatives using phenyl hydrazine, ethyl acetoacetate and aromatic aldehydes. The 3-methyl-1-phenyl-1H-pyrazol-5-ol was obtained as in-situ precursor to the series of bis-pyrazolone derivatives. The progress of reaction was monitored by thin layer chromatography. The obtained organic product was further characterized and confirmed by FT-IR, 1 H-NMR, 13 C-NMR and HRMS spectroscopic techniques. The Cu–ZnO catalyst confers upto 96% yield of pyrazolone derivatives in ethanol solvent at refluxing condition. The Cu–ZnO catalyst was used successfully up to 5 cycles without much loss of catalytic activity. Overall, the use of environmental friendly Cu–ZnO nano- structures as a heterogeneous catalyst shows higher yield and lower reaction time towards the synthesis of bispyrazolone derivatives by Tandem Knoevenagel/Michael reaction. Keywords: Heterogeneous Catalyst, Nanocrystalline Cu–ZnO, Bispyrazolone, One Pot Synthesis, Tandem Knoevenagel/Michael Reaction. 1. INTRODUCTION The role of pyrazolone compounds has been increasing day by day in pharmaceutical industries due to its nitro- gen containing five membered heterocyclic moieties. Con- sequently, nowadays the researchers are actively involved in the synthesis of pyrazolone derivatives due to its enor- mous applications as drug molecules. 1 The pyrazolone moiety containing compounds exhibits biological activities ∗ Authors to whom correspondence should be addressed. such as antioxidant, antidepressant, gastric secretion stim- ulatory, anti-inflammatory 2 etc. Furthermore, these com- pounds have been efficiently used as herbicidal, analgesic, antimicrobial, antifungal and antipyretic drugs. 3 These compounds have unique electrical and optical properties 4 too. The 4,4 ′ -((aryl)methylene)bis(3-methyl-1-phenyl-1H- pyrazol-5-ol) derivatives are routinely applied as pesti- cides, fungicides, insecticides in the pesticide industries 5 6 and used as chelating agent for the extraction of different metal ions. 7 J. Nanosci. Nanotechnol. 2019, Vol. 19, No. 8 1533-4880/2019/19/4623/009 doi:10.1166/jnn.2019.16490 4623