Synthesis of  (2-Chloropyridine-3-yl)-(4-nitrobenzylidene) amine and  its antibacterial activity

A. A. jarrahpour*¹, M. Motamedifar², H. Mousavipour¹,  N. Hadi² and M. Zarei¹

1 Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71454, Iran Tel.  0098 711 2284822,  Fax: 0098 711 2280926, E-mail: [email protected],  [email protected]

2 Department of Bacteriology & Virology, Shiraz Medical School, Shiraz University Medical Science, Shiraz 71345, Iran

Received: 24 October 2003 / Accepted: 11 February 2004 / Published: 24 February 2004

Keywords : Schiff base, 3-amino-2-chloropyridine, p-nitrobenzaldehyde, biological activity, ab initio

Schiff bases are reported to show a variety of biological activities such as antibacterial [1-3], antifungal [4-5], anticancer [6-7] and herbicidal [8] activities . Pyridinium compounds have biological activities [9] such as antifungal [10] and antibacterial [10-11] activities. The presence of a chloro moiety in different types of compounds causes them to exhibit pesticidal activity⁸. Based on these facts , we synthesized 2-chloro pyridin-3-yl–(4-nitrobenzylidene) amine 3. According to ab initio calculations at the  HF/6-31G (d,p) level, Schiff base 3  at dihedral angel of  42.9 ^o  is about  15.70 kj/mol  more stable than the coplanar  pyridine and nitrophenyl rings (Figure 1). The titled compound was tested against S. aureus, B. subtilis, K. pneumonia and P. aeruginosa by the disk diffiusion method and was not active at the level of  200 μg/disk.

A mixture of  3-amino-2-chloropyridine 1(1.28 g, 10.00 mmol), 4-nitrobenzaldehyde 2 (1.51 g, 10.00 mmol) and anhydrous magnesium sulfate (4.00 g) in dry dichloromethane (40.00 mL) was stirred at room temperature for four hours. The suspension was filtered and washed with dichloromethane.The solvent was evaporated under reduced pressure and Schiff base 3 was formed as a yellow solid  which was recrystalized  from  warm ethanol (2.23 g , 85% ).

m.p.146-148 ^oC.

IR (KBr) (cm^-1): 1340.40 and 1517.90  (NO₂), 1600.0 (N=CH), 1633.60 (C=N  pyridine ring) .

¹H-NMR (CDCl₃) (250 MHz)(ppm): 7.23-8.38 (m , 7 H,  Ar-H), 8.54 (s, 1H,  CH=N).

¹³C- NMR (CDCl₃) (62.90 MHz)(ppm): 123.65-147.18 (2 ph), 161.41 (CH=N).

MS (m/z, %): 261 (M ⁺, 64.90), 149 (NO₂Ph-C=N, 36.00 ), 126(C₅H₃NClN, 15.00 ), 112 (C₅H₃NCl, 34.00), 92( C₅H₃N₂, 29.00 ), 77 ( C₅H₃N, 31.20), 53 (N=CH-CH=CH, 35.00), 51 (N=C-C=CH, 100.00).

Figure 1 : The minimum energy conformation of Schiff base 3

Acknowledgment

The authors thank the Shiraz University Research Council for financial support (Grant No. 81-SC-1495-C191 ).

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