Zn(II), Cd(II) and Hg(II) complexes with a general composition[M(L)2(X)2], where L=4-aminopyridine (4AP) and X=NO2 − were prepared under microwave irradiation. The metal complexes were characterized by elemental analyses, molar conductance, IR, Far-IR, electronic, NMR (1 H, 13 C), XPS spectral and thermal studies. The spectroscopic studies reveal the composition, different modes of bonding, electronic transition, different chemical environment of C and H atoms and the electronic state of the metal atoms. On the basis of the characterization data, tetrahedral geometry is suggested for all the complexes. The free ligand (4-aminopyridine) and their metal complexes were screened against phytopathogenic fungi and bacteria in vitro and the activities were compared.
The biological activity of the aminopyridines and their transition metal complexes act as K + and Ca 2+ channel inhibitors has been discussed in the literature 1,2. 3-aminopyridine (3AP) possesses significant antiproliferative, antiinflammatory and antibacterial activities 3 and furthermore, an antitumor activity of its derivatives has also proposed 4. Metal aminopyridine complexes are generally used as asymmetric catalysts for various reactions such as hydrogenation, cyclopropanation, epoxidation etc 5. The versatile coordination modes of the ambidentate ligand nitrite ion (NO2-) were previously reported 6. Metal nitrito complexes (M-ONO) are in general used as photochemical NO precursors 7. The transition metal complexes have many applications in pharmaceutical industries, biology and medicine. They posses electrical, thermo chromic, catalytic, antibacterial and antifungal properties 8 , Metal complexes of chromium, nickel and copper have a wide range of applications such as dyes and pigments 9. Many drugs possess modified toxicological and pharmacological properties in the form of metal complexes and the most widely studied in this respect is the Cu(II) ion which has proved beneficial in many diseases such as tuberculosis, gastric ulcers, rheumatoid arthritis and cancers 10. Copper complexes are currently being investigated for their potential anticancer activity. Moreover, coordination with copper often enhances the activity of various types of drugs such as antitumor and antiinflammatory agents 11 .
ABSTRACT. Microwave assisted syntheses of Zn(II), Cd(II) and Hg(II) complexes with 3-aminopyridine (3AP) and nitrite (NO2 − ) ions have been reported. The metal complexes were characterized by elemental analyses, molar conductance, IR, Far-IR, electronic, NMR ( 1 H, 13 C), thermal and electron impact mass spectral studies. The spectroscopic studies reveal the composition, the nature of nitrite ligand in the complexes, electronic transitions, chemical environments of C and H atoms thermal degradation of the complexes. On the basis of characterization data, distorted tetrahedral geometry is suggested for Zn(II), Cd(II) and Hg(II) complexes. The organic ligand (3AP) and their metal complexes were screened against gram negative pathogenic bacteria and fungi in vitro. The results are compared with our previous report J. Korean Chem. Soc. 2013, 57, 341 on 4-aminopyridine and nitrite ion complexes of the same metal ions.
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