Hindawi Publishing Corporation Journal of Chemistry Volume 2013, Article ID 436758, 13 pages http://dx.doi.org/10.1155/2013/436758 Research Article Synthesis and Evaluation of Novel Fluorinated 2-Styrylchromones as Antibacterial Agents Mehbub Momin, 1 Deresh Ramjugernath, 2 Hafizah Chenia, 3 and Neil A. Koorbanally 1 1 School of Chemistry, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa 2 School of Chemical Engineering, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa 3 Department of Biochemistry, Genetics, and Microbiology, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa Correspondence should be addressed to Neil A. Koorbanally; koorbanally@ukzn.ac.za Received 27 May 2013; Revised 8 August 2013; Accepted 16 August 2013 Academic Editor: Hugo Verli Copyright © 2013 Mehbub Momin et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A range of luorinated 2-styrylchromones (5a–g) of which six were new (5a–f ) were prepared in three steps using the Baker- Venkataraman rearrangement along with two methoxylated derivatives (5h-i) and a methylenedioxy derivative (5j) and screened for their antibacterial activity using Gram-positive bacteria (Staphylococcus aureus, sciuri, and xylosus as well as Bacillus subtilis) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia). he compounds were most efective against B. subtilis followed by S. aureus and a single strain of E. coli (ATCC 25922). Diluorination on the phenyl ring was shown to enhance antibacterial activity, and luorine substitution at the 6 position was shown to be far superior to substitution at the 7 position. In comparison to tetracycline, the activity indices of the luorinated styrylchromones ranged from 0.50 to 0.75 against B. subtilis. he crystal structure of 2  -luoro-2-styrylchromone is also presented, and the molecule was shown to be planar. 1. Introduction Fluorinated compounds have a wide range of medical ap- plications such as anti-inlammatory, antiviral, anti-HIV, an- tibacterial, anticancer, antimalarial, antidepressants, antipsy- chotics, anaesthetics, and steroids [1, 2]. Introducing luorine atoms into drugs can also alter the rate and route of drug metabolism [1], and stereoelectronic factors associated with the luorine atom can lead to changes in the biological action of molecules in comparison to its hydroxyl or hydrogen analogues [3]. he substitution of luorine for hydrogen or hydroxy groups can lead to changes in the mechanism of the drug as well as enzyme inhibition [3]. he small size of the luorine atom, the enhanced lipophilicity it imparts to the molecules, and the electronegativity of the atom oten result in improved therapeutic drugs [2]. As part of an ongoing study on luorinated pharmaceutical compounds, we have chosen to explore the antibacterial efects of luorinated 2- styrylchromones. he biological activities of 2-styrylchromones have recently been reviewed by Gomes et al. [4]. he 2-sty- rylchromones were shown to be A 3 adenosine receptor antagonists [5], have hepatoprotective activity [6], be potent antioxidants [7], have antiallergic properties [8], antiviral activity [9], and anticancer activity [10–12], and display xanthine oxidase inhibition to treat, for example, gout, hyper- tension, and hepatitis linked to xanthine oxidase activity [13]. he synthesis of these compounds has been reviewed by Silva et al. [14]. In one synthetic approach, it involves the aldol condensation between cinnamaldehydes and 2  -hy- droxyacetophenones followed by an oxidative cyclisation [15]. It was also synthesised by the Baker-Venkataraman rear- rangement, involving the O-acylation of 2  -hydroxyaceto- phenones with cinnamic acids, followed by rearrangement of the ester and then cyclisation into the styrylchromone [16]. hey can also be made directly from 2  -hydroxyacetophe- nones with cinnamoyl chlorides [17].