INTRODUCTION Various Schiff bases (mono-condensed and bis-condensed) and Schiff base metal complexes derived from the aromatic diamine, 2,3-diaminopyridine (DAPY) have been synthesised in the literature. Eight mono-condensed Schiff bases were reported by Dubey and Ratnam 1 using the following aldehydes (benzaldehyde, 2-nitrobenzaldehyde, 3-nitrobenzaldehyde, 4-X-benzaldehyde {X = CH 3 , Cl, OH, NO 2 , OCH 3 } and five others were prepared, respectively with salicylaldehyde (SalH) 2 , o-vanillin (ValH) 3 , pyrrole-2-carbaldehyde 4 , 3-ethoxy- vinylidene-2,4-pentanedione 5 and 3-oxo-3-(4’-nitrophenyl)- propionaldehyde 5 . On the other hand, bis-condensed Schiff bases with SalH 2,6-8 , ValH 3,9 , 5-bromosalicylaldehyde 10 , 2-hydroxy-1-naphthaldehyde 4,11 , 3-methoxy-4-butoxybenzal- dehyde 12 , 3-methoxy-4-carboxymethylbenzaldehyde 12 and ethoxyvinylidene-2,4-pentanedione 5 and only one bis-con- densed mixed Schiff base with 4-hydroxybenzaldehyde and SalH 6 have been reported. From the above Schiff bases, several copper, iron, nickel, ruthenium and zinc complexes were synthesized 3,4,6-8,10,13,14 . The structures of the copper(II) and nickel(II) Schiff base complexes derived from DAPY and SalH and that of zinc(II) complex derived from DAPY and 5-bromosalicylaldehyde have been determined by X-ray crystallography 8,10,13 . Some of the Schiff bases and/or their metal complexes were tested as catalytic oxidants 4 , anti- Synthesis and Antibacterial Activity of New Schiff Bases Derived from 2,3-Diaminopyridine and Their Copper(II), Iron(III), Nickel(II) and Zinc(II) Complexes HENRI T.Y. LI KAM WAH * and SAVITREE BANGARIGADU-SANASY Department of Chemistry, University of Mauritius, Réduit, Mauritius *Corresponding author: Tel: +230 4037878; E-mail: lkwah@uom.ac.mu (Received: 17 January 2013; Accepted: 20 September 2013) AJC-14149 Three new bis-condensed Schiff bases (1-3), one imidazo-pyridine (4) and twelve Schiff base metal complexes derived from 2,3- diaminopyridine (DAPY) have been synthesised. The mixed Schiff bases DAPY-{ValH}{SalH} (1) and DAPY-{ValH}(DhbH2} (2) were obtained by equimolar reaction of the mono-condensed Schiff base of DAPY and o-vanillin (ValH), DAPY-{ValH}with salicylaldehyde (SalH) and 2,3-dihydroxybenzaldehyde (DhbH2), respectively. 1:2 Molar condensation of DAPY with DhbH2 yielded the Schiff base (3), whereas reaction of the same reagents in a 1:0.8 mol ratio gave the imidazo-pyridine, 2-(2,3-dihydroxyphenyl)-1H-imidazo-(4,5-b)pyridine (4). The Schiff bases and Schiff base metal complexes (1600 μg cm -3 ) were screened in vitro against three bacteria (Staphylococcus aureus, Bacillus subtilis and Escherichia coli) using the diffusion method. Some of them were found to be more active than the control cetyl trimethyl ammonium bromide. Key Words: Schiff bases, 2,3-Diaminopyridine, 2,3-Dihydroxybenzaldehyde, o-Vanillin, Salicylaldehyde, Antibacterial, Imidazo-pyridine. microbial agents 3,4,6,12 , analytical reagent 7 or electrochemical sensor 9 . In continuation of our work on Schiff bases derived from DAPY 3,4,6 we now report the synthesis of three new bis- condensed Schiff bases (1-3), of which two are mixed, one imidazo-pyridine (4) and twelve transition metal (copper, iron, nickel and zinc) Schiff base complexes (1a-1d), (2a-2d) and (3a-3d). EXPERIMENTAL All chemicals (analar grade) were purchased from either Aldrich or BDH and used as received. IR spectra of the samples were recorded as KBr pellets on a FTIR Mattson 1000 spectro- meter in the 4000-400 cm -1 region. 1 H and 13 C NMR spectra in DMSO-d6 were obtained from a Bruker Spectrospin 250. Magnetic susceptibilities of metal complexes were determined using a Sherwood Scientific magnetic balance. Copper, iron, nickel and zinc content were found using a Unicam 929 atomic absorption spectrometer, whereas C, H and N analyses were obtained using a LECO 932 CHNS analyzer. Melting points were measured using a Stuart Scientific melting point appa- ratus and were uncorrected. Mass spectra were recorded on a Fissions VG Trio 2000 mass spectrometer, University of Manchester. Preparation of Schiff bases: The mono-condensed Schiff base DAPY-{ValH} was synthesized using literature procedures 1,3 . Asian Journal of Chemistry; Vol. 25, No. 16 (2013), 9221-9225 http://dx.doi.org/10.14233/ajchem.2013.15175