Synthesis, structural characterization and biological activity of fluorinated Schiff-bases of the type [C 6 H 4 -1-(OH)-3-(CH@NAr F )] Alcives Avila-Sorrosa a,⇑ , Jorge Ignacio Hernández-González a , Alicia Reyes-Arellano a , Rubén A. Toscano b , Reyna Reyes-Martínez b , J. Roberto Pioquinto-Mendoza b , David Morales-Morales b,⇑ a Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Carpio y Plan de Ayala S/N, Colonia Santo Tomás, México, DF 11340, Mexico b Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, México, C.P. 04510, Mexico highlights  A series of fluorinated imines were synthesized in a facile manner in high yields.  Good antibacterial activities were observed.  The position of the fluorine substituents is determinant on the biological activity.  Studies in the solid state reveal important non-covalent interactions.  This weak interactions may be important for the biological activities. graphical abstract article info Article history: Received 21 September 2014 Received in revised form 28 December 2014 Accepted 29 December 2014 Available online 6 January 2015 Keywords: Fluorinated Schiff bases Crystal structures Anti-bacterial activity Supramolecular arrangements Non-covalent interactions abstract A series of fluorinated imines of the type [C 6 H 4 -1-(OH)-3-(CH@NAr F )]; Ar F @C 6 H 4 -4-F (1), C 6 H 3 -2,3-F 2 (2), C 6 H 3 -3,5-F 2 (3), C 6 H 2 -2,4,6-F 3 (4), C 6 H 4 -3-CF 3 (5), C 6 H 3 -3,5-(CF 3 ) 2 (6), were synthesized and fully characterized including single crystal X-ray diffraction analyses of compounds [C 6 H 4 -1-(OH)-3-(CH@NC 6- H 4 -4-F)] (1), [C 6 H 4 -1-(OH)-3-(CH@NC 6 H 3 -3,5-F 2 )] (3), [C 6 H 4 -1-(OH)-3-(CH@NC 6 H 4 -3-CF 3 )] (5). Further analyses of these results allowed the identification of the predominant non-covalent interactions and supramolecular arrangements in the solid state. Exploration of the anti-bacterial activity against both gram-positive and gram-negative bacteria showed those compounds including F or CF 3 substituents at the meta positions i.e. [C 6 H 4 -1-(OH)-3-(CH@NC 6 H 3 -3,5-F 2 )] (3), [C 6 H 4 -1-(OH)-3-(CH@NC 6 H 4 -3-CF 3 )] (5), [C 6 H 4 -1-(OH)-3-(CH@NC 6 H 3 -3,5-(CF 3 ) 2 )] (6), to be the best when their activity is compared versus ampicillin. Ó 2015 Elsevier B.V. All rights reserved. Introduction Fluorinated compounds have gained an increasing interest due to their successful applications in different fields of chemistry, such as supramolecular studies, design of new materials and as impor- tant starting materials in the syntheses of new molecules with bio- logical functions [1–3]. The introduction of fluorine into an organic molecule via electrophilic or nucleophilic reactions and most com- monly, from fluorinated building blocks, have become a key in the search and discovery of new drugs or increasing the activity of those that already exist. Although fluorine and hydrogen have sim- ilar steric parameters and similar van der Waals radii, 1.2 and 1.35 Å respectively; fluorine can cause significant changes in an organic molecule, mainly by its electron-withdrawing inductive http://dx.doi.org/10.1016/j.molstruc.2014.12.080 0022-2860/Ó 2015 Elsevier B.V. All rights reserved. ⇑ Corresponding authors. Tel.: +52 55 56224514; fax: +52 55 56162217. E-mail addresses: aavilas@ipn.mx (A. Avila-Sorrosa), damor@unam.mx (D. Morales-Morales). Journal of Molecular Structure 1085 (2015) 249–257 Contents lists available at ScienceDirect Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc