Metal complexes of carboxamidrazone analogs as antitubercular agents. 1. Synthesis, X-ray crystal-structures, spectroscopic properties and antimycobacterial activity against Mycobacterium tuberculosis H(37)Rv

N(1)-Benzylidene-pyridine carboxamidrazones and their metal conjugates have emerged as a new class of potential antimycobacterial agents. Nine such carboxamidrazone analogs (L(1)-L(9)) along with their Cu(II) (MC(1)-MC(9)) and Fe(III) (MC(10)-MC(18)) complexes were synthesized. Single crystal X-ray structures of copper complexes MC(1) and MC(5) were determined which suggest slightly distorted square planer geometries for copper complexes and octahedral geometries for ferric compounds. All compounds were evaluated for their in vitro antimycobacterial activity against Mycobacterium tuberculosis H(37)Rv. The results show 32-64-fold enhancement in antitubercular activity upon copper complexation.