Two New Co(II) and Ni(II) Complexes with 3-(2-Pyridyl)pyrazole-Based Ligand: Synthesis, Crystal Structures, and Bioactivities

Abstract

Over the past decades, investigations on DNA interactions with transition metal complexes, especially for those containing multidentate aromatic ligands, have aroused considerable interests owing to their potential applications as new therapeutic agents and interesting properties that make them as possible probes of DNA structure and conformation. 1,2) The studies on DNA metallointercalators, which can react at specific sites along a DNA strand as reactive models for proteinnucleic acid interactions, have provided us with some effective routes toward rational drug design as well as approaches to develop sensitive chemical probes for DNA.3-9) Among them, a number of transition metal complexes with planar aromatic heterocyclic ligands have been used as the probes for DNA secondary structure and therapeutic agents. Usually, their anti-tumor activities can increase more or less compared with those of either the free ligands or metal ions alone, which may be due to the different binding properties of these complexes to DNA. [10][11][12][13] It is necessary to understand the DNA binding properties for developing new potential DNA targeting anti-tumor drugs. In general, metal complexes interact with double helix DNA in either non-covalent or covalent way, the former including three binding modes, namely, intercalation, groove binding and external static electronic effects. In these interactions, it should be pointed out that intercalation is a significantly important binding mode to DNA. In fact, DNA intercalators are some small molecules that contain a heterocyclic functional group with the structure of planar aromatic ring, which can insert and stack between the base pairs of doublehelical DNA. Meanwhile, the intercalative capability of DNA metallointercalators appears to be influenced by several factors such as the planarity of ligand, atom type of ligand donor and the coordination geometry.14-16) Moreover, the types of different metal ions and their flexible valences, which usually are responsible for the coordination geometry of complexes, also have significant influences on the intercalating ability of transition metal complexes to DNA. 17,18) In our previous work, a new 3-(2-pyridyl)pyrazole-based ligand L (see Chart 1) and its Cu(II), Zn(II) and Cd(II) com- 19,20) Obviously, the Cu(II) complexes were found to possess higher affinity to DNA and cytotoxic activity against different tested cancer cell lines (such as HL-60, BGC-823 and MDA-MB-435) as compared with Zn(II) and Cd(II) complex as well as the free ligand L. In attempt to further touch more insights into the relationship between structures and DNA-binding properties of such transition metal complexes, as well as to develop new useful DNA probes, herein, we report the synthesis and crystal structures of another two new complexes with L ligand, [Co(L) 3 ](ClO 4 ) 2 (1) and [Ni(L) 3 ](ClO 4 ) 2 (2). Moreover, the binding behaviors of these compounds with calf thymus DNA (CT-DNA) have been investigated in detail by thermal denaturation, viscosity measuremen...

Synthesis, Crystal Structure Analyses, and Antibacterial Evaluation of the Cobalt(II) Complex with Sulfadiazine-Pyrazole Prodrug

“…The unit cell parameters were a = 7.73330 (10) 2 displays the asymmetric unit of the studied complex, while the selected bond lengths and angles are presented in Table 1. the Co-N distances were 2.122(4)-2.213(4) Å [35] and 2.1035(19)-2.1831(19) Å [34], respectively, while the Co-O distance was 2.0845(18) Å [35]. These values confirmed the high-spin state of the studied complex.…”

Synthesis, structural characterization and cytotoxicity of nickel(II) complexes containing 3,3-dialkyl/aryl-1-benzoylthiourea ligands

“…Selective guanosine binding and cytotoxicity of benzimidazole derived dinickel complexes were tested against U937 (human leukemic cell line), Raw 264.7 (macrophage cell line), HeLa (human cervical cancer cell line) and L02 (human hepatocytes cell line) [5]. The cytotoxic activity of Ni(II) complexes with 3-(2-pyridyl)pyrazolate-based ligands was evaluated in vitro against three different cancer cell lines, HL-60 (human leukemia), BGC-823 (stomach cancer) and MDA-MB-435 (mammary cancer) [6]. In this contribution, screening for cytotoxicity is elaborated to include nickel(II) complexes of thiourea derivatives.…”

Deciphering the sensing of α-amyrin acetate with hs-DNA: a multipronged biological probe

“…Hence, viscosity characteristics have minimal ambiguity and the ultimate reproving test for deciphering the system of binding of miniature molecules to DNA. 50 Classical intercalators proliferate viscosity of DNA significantly, causing the separation of base pairs at the intercalation sites and leading to an overall increase in the length of DNA. 51 In contrast, minimal changes in viscosity are observed on binding to the DNA grooves.…”