Synthesis, bioassay, crystal structure and ab initio studies of Erlenmeyer azlactones Mehtab Parveen a,⇑ , Akhtar Ali a , Sarfaraz Ahmed a , Ali Mohammed Malla a , Mahboob Alam b , P.S. Pereira Silva c , Manuela Ramos Silva c , Dong-Ung Lee b a Department of Chemistry, Aligarh Muslim University, Aligarh 202-002, India b Division of Bioscience, Dongguk University, Gyeongju 780-714, Republic of Korea c CEMDRX Physics Department, University of Coimbra, 3004-516 Coimbra, Portugal highlights " 4-Arylidene-2-phenyl-5(4H)- azlactones were synthesized and fully characterized. " Antimicrobial and antioxidant activity. " The structure of 5 & 6 were studied by X-ray study and compared to DFT calculations. " DFT calculations of two compounds were suggested the stability of the Z-conformer. " Crystal packing was stabilized by H-bond, weak CAHp and pp interactions were observed. graphical abstract A series of 4-arylidene-2-phenyl-5(4H)-azlactones have been synthesized, characterized on the basis of systematic spectral studies and screened for their biological activity. Moreover, the Z-configuration and stability of compounds was ascertained on the basis of spectroscopy techniques, X-ray studies as well as DFT calculations. article info Article history: Received 21 May 2012 Received in revised form 10 November 2012 Accepted 18 November 2012 Available online 5 December 2012 Keywords: Aromatic azlactones Bioassay (4Z)-4-(3,5-dimethoxybenzylidene)-2- phenyl-1,3-oxazol-5(4H)-one Crystal structure DFT calculation abstract Several 4-arylidene-2-phenyl-5(4H)-azlactones have been synthesized via Erlenmeyer method. The syn- thesized compounds have been characterized on the basis of systematic spectral studies (IR, 1 H NMR, 13 C NMR, and MS). The compound (4Z)-4-(3,5-dimethoxybenzylidene)-2-phenyl-1,3-oxazol-5(4H)-one, C 18 H 15 NO 4 ,(5), crystallizes in the orthorhombic system, space group P2 1 2 1 2 1 , with a = 5.6793(3) Å, b = 15.2038(7) Å, c = 17.6919(10) Å, Mr = 309.31, V = 1527.64(14) Å 3 , Z= 4 and R = 0.0547. The compound (4Z)-2-phenyl-4-(3,4,5-trimethoxybenzylidene)-1,3-oxazol-5(4H)-one, C 19 H 17 NO 5 ,(6) crystallizes in tri- clinic geometry with space group P-1, having unit cell parameters a= 7.3814(3) Å, b = 8.1446(3) Å, c = 13.9845(5) Å, a = 86.918(3), b = 83.314(2), c = 82.462(3), Mr = 339.34, V= 827.16(5) Å 3 , Z= 2 and R = 0.0433. The DFT calculations of compounds (5) and (6) have been carried out to ascertain the stability of Z-conformer. The in vitro antimicrobial activity of all the compounds (1–6) was evaluated by the disk diffusion method against gram +ve and gram ve microorganism and fungal strains. The MIC of the syn- thesized compounds was determined by agar well diffusion method in 96-well microtiter plate. All the synthesized compounds were also screened for their free radical scavenging activity by DPPH method. Ó 2012 Elsevier B.V. All rights reserved. Introduction During the past few decades many research papers have been published in the area of Erlenmeyer synthesis by using different methods [1–5]. The synthesis of azlactones involves the condensa- tion of aromatic or aliphatic aldehydes and hippuric acid with a 1386-1425/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.saa.2012.11.054 ⇑ Corresponding author. Mobile: +91 9897179498. E-mail address: mehtab.organic2009@gmail.com (M. Parveen). Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 104 (2013) 538–545 Contents lists available at SciVerse ScienceDirect Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal homepage: www.elsevier.com/locate/saa