Antimicrobial activity of novel synthesized coumarin based transitional metal complexes

Sahoo, Jyotirmaya; Paidesetty, Sudhir K.

The metal complexes of 3-aryl-azo-4-hydroxy coumarin analogues were synthesized by refluxing different hydro alcoholic solutions of metal chlorides with 3-(4-chloro phenyl/4-methoxy phenyl)-azo-4-hydroxy coumarin analogues (Scheme 1) and finally re-crystallized from diethyl ether. The structures of the prepared compounds are confirmed by different instrumental methods of analysis. The physical characteristics of the synthesized compounds are reported in Table 1 . The FT/IR spectra of synthesized ligands 3a and 3b showed strong vibration bands at 3479e 3445 cm À1 , 1619e1603 cm À1 , 1726e1745 cm À1 , 1298e 1246 cm À1 and 1529e1505 cm À1 due to presence of functional groups such as OH str., C]C str., C]O str., CeO str. and N]N str., respectively. The strong vibration bands of compound 3a at 1726, 1619 and 1298 cm À1 may be due to presence of a lactone carbonyl of C]O str., C] C str. and ]CeO str., respectively, and are illustrated in Figure 1 . The frequencies of all the complexes (4ae4h) assigned at 1629e1613 cm À1 , 1729e1721 cm À1 , 1296e 1248 cm À1 and 1529e1524 cm À1 correspond to C]C str., C]O str., CeO str. and N]N str., respectively. The IR spectral bands of all metal complexes appearing at 451e441 and 538e531 cm À1 are assigned to (MÀN) and (MÀO), respectively. The 1 H NMR spectra of the ligands showed a broad singlet at d 16.81e16.86 ppm towards the presence of the enolic OH group of 4-hydroxy coumarin. The 1 H NMR spectrum of compound 3b showed a sharp singlet at d 3.83 ppm corresponding to the proton of eOCH 3 ( Figure 2 ). All of the complexes showed signals at a range of (6.90e7.26)e(7.23e7.37) ppm corresponding to {m, 8H, (C 6 H 4 ) 2 }.