ISSN: 2410-9649 Deeba et al / Chemistry International 4(4) (2018) 206-215 iscientic.org. 206 www.bosaljournals/chemint/ editorci@bosaljournals.com Article type: Research article Article history: Received February 2018 Accepted June 2018 October 2018 Issue Keywords: 1,3,4-oxadiazole Hydrazones Copper complexes Antibacterial Antifungal activities A series of novel 1, 3, 4-oxadiazole analogues was synthesized from cyclization of hydrazones of substituted 1-ethyl-1,4-dihydro-7-methyl-4-oxo-1,8- naphthyridine-3-carbohydrazides were prepared from nalidixic acid. The structures of synthesized oxadiazole derivatives and their copper complexes were elucidated on the basis of FTIR, elemental analyses, 1 H-NMR and atomic absorption spectral analysis. It was observed from spectral data that metal ligand ratio was 1:1 in all copper complexes and they were bidentate, coordination was found to be done through oxygen of 4-oxo group and nitrogen of oxadiazole ring. The synthesized compounds were further evaluated with biological activities and compared with parent hydrazones. Copper complexes possess antibacterial and antifungal activities better than the oxadiazoles while they have better antioxidant activity then copper complexes. Parent hydrazones were better in all biological activities than synthesized oxadiazoles. © 2018 International Scientific Organization: All rights reserved. Capsule Summary: A series of novel 1,3,4-oxadiazole analogues was synthesized from cyclization of hydrazone. The synthesized compounds showed considerable biological activities than synthesized oxadiazoles. Cite This Article As: F. Deeba, N. Abbas, M. T. Butt, R. A. Khan, M. M. Ahsan and M. A. Khan. Synthesis, characterization and biological activities of 1,3,4-oxadiazole derivatives of nalidixic acid and their copper complexes. Chemistry International 4(4) (2018) 206-215. INTRODUCTION Nalidixic acid (1-ethyl-7-methy-1,8-naphthyridine-4-one-3- carboxylate, C12H12N2O3,) was the first developed compound of the family of quinolone and 1,8-naphthyridines. It was described by Lesher and his coworkers in (Lesher et al., 1962) and since then it has been used extensively in therapy (Aggarwal et al., 2010; Cotton et al., 1999; Miessler and Tarr, 1999). 1, 8-naphthyridine derivatives have been investigated for a long period of time to report complexation properties and medicinal uses e.g., possess antibacterial, anti- inflammatory, anti-hypertensive and anti-platelet activities. After the discovery of first quinolone, nalidixic acid, medicinal and industrial chemists have made numerous structural modification and new quinolones (Chen et al., 2001; Roma et al., 2000) have continually been made, in the hope of incremental microbiological advantages over Nalidixic acid which displays remarkable potency against gram negative as well as gram positive and anaerobic organisms (Das, 1990). Chemistry International 4(4) (2018) 206-215 Synthesis, characterization and biological activities of 1,3,4-oxadiazole derivatives of nalidixic acid and their copper complexes Farah Deeba 1 , Naeem Abbas 1,* , Muhammad Tahir Butt 1 , Rauf Ahmad Khan 1 , Muhammad Muneeb Ahsan 2 and Misbahul Ain Khan 3 1 Center for environmental protection studies, PCSIR Laboratories Complex, Lahore Pakistan. 2 ICET, Institute of Chemical Engineering and Technology, University of the Punjab, Lahore, Pakistan 3 Professor Emeritus, Institute of Chemistry, Islamia University Bhawalpur, Pakistan *Corresponding author’s E. mail: naeemchemist@gmail.com ARTICLE INFO ABSTRACT