Abstract:
Three Zn(II) complexes, namely, [Zn3(L1
)2]4CH3CN (1), [Zn3(L1
)2(H2O)4]H2O2DMF (2) and [Zn2(L2
)2
(H2O)22H+]2ClO4
(3) were synthesized by reacting nitrophenol-based tripodal and dipodal Schiff-base
ligands with Zn(II) salts. The complexes were characterized using different techniques such as elemental
analyses, ESI-MS, IR and NMR. The solid-state structures of all the complexes were determined.
Complex 1 has a rigid trinuclear structure with an octahedral environment around each metal ion. The
coordination environment of the rigid trinuclear complex 1 was purposely disturbed by changing the
reaction conditions to obtain the flexible trinuclear complex 2. The dinuclear complex 3, containing
coordinated water molecules, was also synthesized. DNA binding abilities and phosphatase-like activities
of all the complexes were investigated. The catalytic activity of the rigid trinuclear complex 1 was
compared with the cup shaped trinuclear complex 2 and closed structure dinuclear complex 3. The
different structural factors (such as flexibility of the complex, number of metal centers, labile sites at the
metal centre and coordination environment around the metal center) collectively modulate the
phosphatase-like activity toward the transesterification of 2-hydroxypropyl-p-nitropenylphosphate
(HPNP). Complex 2 exhibits the highest catalytic activity among all the complexes due to its flexible
cup-shaped structure, three metal centers and coordinated water molecules.
