Synthesis, Crystal Structure, and Biological Activity of cis/trans Amide Rotomers of (Z)-N′-(2-Oxoindolin-3-ylidene)formohydrazide

(Z)-N'-(2-Oxoindolin-3-ylidene)formohydrazide (2) was synthesized by the reaction of (Z)-3-hydrazonoindolin-2-one (1) with formic acid under reflux. The structure of 2 was characterized by IR, Mass, H-1 NMR, and X-ray crystal structure determination. Interestingly, compound 2 appeared in DMSO-d(6) as cis and trans amide rotomers in 25% and 75%, respectively. The X-ray analysis showed the Z geometrical isomer of 2 around -C=N- for cis and trans amide rotomers. The crystal of 2 belongs to monoclinic, space group P2(1)/c, with a = 4.5206 (1) angstrom, b = 22.4747 (7) angstrom, c = 17.3637 (5) angstrom, beta = 103.752 (1)degrees, Z = 8, V = 1713.57 (8) angstrom(3), D-c = 1.467 Mg m(-3), mu = 0.11 mm(-1), F(000) = 784, R = 0.047, and wR = 0.123 for 3798 observed reflections with I > 2 sigma(I). Compound 2 exhibited a moderate activity in its antimicrobial evaluation against E. coli and P. aeruginosa and a good activity against S. aureus close to that of the standard drug ciprofloxacin. The in vitro anticancer activity of 2 was evaluated against two human tumor cell lines, namely, HepG2 hepatocellular carcinoma and MCF-7 breast cancer. HepG2 cancer cell line was more susceptible to compound 2 than MCF-7.