In present work, new Schiff-base
ligand, N-2-(6-methylpyridyl)-2-hydroxy-
1-naphthaldimine (1) and its Ni(II) complex,
bis[N-2-(6-methylpyridyl)-2-oxo-1-
naphthaldimnato-k3N^N^O] nickel(II) (2)
have been reported and characterized
by spectral techniques (IR, 1H NMR, Mass).
Solid state structures and non-covalent
interactions have great effect on the stability
of the final structures. X-ray diffraction study
shows zwitter ionic keto-amine tautomer
form of planar Schiff base 1 that exists as dimer
formed by C13 ̶ H13A•••O1i [(i) -x+1, -y, -z+1]
hydrogen bonds and distorted octahedral
geometry around Ni+2 center in chelate 2
where overall crystal structure stability may
be credited to weak C ̶ H•••π, π•••π stacking,
van der Waals interactions, and C ̶ H•••O
type intermolecular hydrogen bonds. The
anticancer activity has been investigated
using cytotoxicity measure (MTT assay),
apoptosis assay, quantitative polymerase
chain reaction (qPCR), and colony
formation assays. The Ni(II) metal complex
demonstrates dose-dependent cytotoxicity
in vitro, killing A549 lung cancer cells via an
apoptotic pathway. MTT assay results direct
to the fact that at higher concentration, 2
showed toxic effect in Beas-2B cells, while
1 showed almost similar cytotoxic effect
(IC50=85.72 μM) as compared to A549 cells.
On the A549 lung cancer cell line, the novel
Ni(II) complex 2 has a good cytotoxic effect
and causes apoptotic cell death. Colony
forming assay study reveals that both 1 and
2 affect the proliferation and growth rate of
cells at different doses, in fact, 2 inhibited
colonization in HUH7 and HCT116 cells more
than 1.