Comparative DNA Binding Abilities and Phosphatase-Like Activities of Mono-, Di-, and Trinuclear Ni(II) Complexes: The Influence of Ligand Denticity, Metal–Metal Distance, and Coordinating Solvent/Anion on Kinetics Studies

Abstract

Six novel Ni(II) complexes, namely, [Ni2(HL(1))(OAc)2] (1), [Ni3L(1)2]·H2O·2CH3CN (2), [Ni2(L(2))(L(3))(CH3CN)] (3), [Ni2(L(2))2(H2O)2] (4), [Ni2(L(2))2(DMF)2]2·2H2O (5), and [Ni(HL(2))2]·H2O (6), were synthesized by reacting nitrophenol-based tripodal (H3L(1)) and dipodal (H2L(2)) Schiff base ligands with Ni(II) metal salts at ambient conditions. All the complexes were fully characterized with different spectroscopic techniques such as elemental analyses, IR, UV-vis spectroscopy, and electrospray ionization mass spectrometry. The solid-state structures of 2, 3, 5, and 6 were determined using single-crystal X-ray crystallography. The compounds 1, 3, 4, and 5 are dinuclear complexes where the two Ni(II) centers have octahedral geometry with bridging phenoxo groups. Compound 2 is a trinuclear complex with two different types of Ni(II) centers. In compound 3 one of the Ni(II) centers has a coordinated acetonitrile molecule, whereas in compound 4, a water molecule has occupied one coordination site of each Ni(II) center. In complex 5, the coordinated water of complex 4 was displaced by the dimethylformamide (DMF) during its crystallization. Complex 6 is mononuclear with two amine-bis(phenolate) ligands in scissorlike fashion around the Ni(II) metal center. The single crystals of 1 and 4 could not be obtained; however, from the spectroscopic data and physicochemical properties (electronic and redox properties) it was assumed that the structures of these complexes are quite similar to other analogues. DNA binding abilities and phosphatase-like activities of all characterized complexes were also investigated. The ligand denticity, coordinated anions/solvents (such as acetate, acetonitrile, water, and DMF), and cooperative action of two metal centers play a significant role in the phosphate ester bond cleavage of 2-hydroxypropyl-p-nitropenylphosphate by transesterification mechanism. Complex 3 exhibits highest activity among complexes 1-6 with 3.86 × 10(5) times greater rate enhancement than uncatalyzed reaction.

Cu(II), Ni(II) complexes derived from chiral Schiff-base ligands: Synthesis, characterization, cytotoxicity, protein and DNA–binding properties

“…However, it has some serious side effects, such as nausea and nephrotoxicity [1,2]. Therefore, many novel metal complexes have been investigated and screened, and some of them are already in clinical trials [3,4]. Indeed, the cytotoxicity effect of metal complexes-mediated is generally accepted to result from their binding and cutting interaction with DNA, which leads to cell cycle arrest, apoptosis and the regeneration of cancers' DNA [5,6].…”

Synthesis and structure of a new trinuclear nickel(II) complex bridged by N‐[3‐(Dimethylamino)propyl]‐N′‐(2‐hydroxyphenyl)oxamido: in vitro anticancer activities, and reactivities toward DNA and protein

“…[45] The absorption spectra of the trinickel(II) complex in the absence and presence of HS-DNA at different concentrations are given in Figure 2A. The K b value of the complex is lower than those observed for classical intercalators (e.g., EB-DNA, ∼10 6 M -1 ), [48] and has the same level as those of some trinickel(II) complexes, [25,26] but higher than those of some mono-and dinickel(II) complexes. [46] To determine quantitatively the affinity of the trinickel(II) complex toward HS-DNA, the intrinsic binding constant (K b ) was determined by monitoring the changes in absorbance at 233 nm for the complex using the following equation [47] : (R = 0.9951 for six points).…”

“…[14] For this reason, many nickel(II) complexes with different ligands have been extensively explored due to their high nucleobase affinity and antitumor activity. [24,25] Considering the importance of nickel(II) complexes with potential antitumor activities, our group has expertise on the synthesis and activity evaluation of trinuclear complexes bridged by asymmetric N,N ′ -bis(substituted)oxamides [26] in recent years. [24,25] Considering the importance of nickel(II) complexes with potential antitumor activities, our group has expertise on the synthesis and activity evaluation of trinuclear complexes bridged by asymmetric N,N ′ -bis(substituted)oxamides [26] in recent years.…”

A Discrete Nickel Cubane with [Ni4O4] Cluster: Synthesis, Structure, and Magnetic Property

“…All the Ni atoms are six coordinated with a distorted octahedral coordination polyhedron, in which three oxygen atoms act as bridges to connect the other remaining three Ni atoms. Up to now, many Ni II cluster-based compounds have been previously reported, such as {Ni 2 }clusters, [14] liner-shaped {Ni 3 }clusters, [15] triangle-shaped {Ni 3 }clusters linked by μ 3 -O atom, [16] rhombus-shaped {Ni 4 }clusters, [17] cubane-like {Ni 4 }clusters, [18] {Ni 5 }clusters with rectangular symmetry, [19] {Ni 6 } clusters constructed by two {Ni 3 }clusters and so on, [10,20] all of which exhibit various magnetic behaviors.…”