Preparation, characterizations and biological evaluations of new copper(II) complexes containing ONO pincer type ligands

Abstract

A new heterocyclic Schiff bases, 6‐methyl/8methyl‐2‐oxo‐1,2‐dihydroquinoline‐3‐carboxaldehyde semicarbazones (H2‐6MOQsc‐H) (H2L1) and (H2‐8MOQsc‐H) (H2L2) and their corresponding copper(II) complexes [CuCl2(H2‐6MOQsc‐H)].3H2O (1), [CuCl2(H2‐8MOQsc‐H)].3H2O (2), [CuNO3(H2‐6MOQsc‐H)(H2O)].NO3 (3) and [CuNO3(H2‐8MOQsc‐H)(H2O)].NO3 (4) have been synthesized and characterized by various physicochemical techniques. The single crystal X‐ray diffraction and spectral data revealed that all of the complexes (1‐4), the ligands coordinated to the Cu(II) ion in a neutral manner via ONO donor atoms and all the complexes exhibited distorted squarepyramidal geometry. The consequence of electronegativity and ring size of nitrogen heterocyclic moiety of ONO donor type of copper(II) chelates on nucleic acid interaction and albumin binding was investigated by in vitro experiments. The interaction of compounds with calf‐thymus DNA (CT‐DNA) has been explored by absorption and emission titration, which exposed those ligands/complexes, could bind with CT‐DNA through electrostatic interaction. The results of gel electrophoresis proved the ability of complexes (1‐4) to cleave the pBR322 plasmid DNA. The interaction of serum albumin (BSA) was investigated by UV‐Vis, fluorescence, synchronous and three dimensional fluorescence spectra. In addition, radical scavenging activity, antifungal activity and cytotoxicity of the newly synthesized compounds were also evaluated. From the results of in vitro studies, it is seen that complex 3 has more potential as compared with other complexes and ligands.

Synthesis, spectroscopic characterization, biological screening and in vitro cytotoxic studies of 4‐methyl‐3‐thiosemicarbazone derived Schiff bases and their Co (II), Ni (II), Cu (II) and Zn (II) complexes

“…It is not restricted to humans only; animals and other living organisms can also get cancer. Cisplatin ( cis diamminedichloroplatinum (II)) discovered in 1845 and licensed for medical use in 1979, is a vivid and glowing metal based drug for cancer therapy but currently some other platinum‐based drugs are being screened through clinical trials in an effort to find a substitute for cisplatin, mainly due to development of resistance in tumor cells and dose‐related adverse effects such as bone marrow suppression, impairment, kidney problems, vomiting, numbness, trouble walking, allergic reactions, heart disease etc …”

Anomalous coordination behaviour of 6‐methyl‐2‐oxo‐1,2‐dihydroquinoline‐3‐carboxaldehyde‐4(N)‐substituted Schiff bases in Cu(II) complexes: Studies of structure, biomolecular interactions and cytotoxicity

“…However, the phenyl substitution on terminal nitrogen of the thiosemicarbazide chain affects not only the coordination mode of the thiosemicarbazone but also the overall geometry of the complex. Finally, complex 4 was confirmed by mass spectroscopy …”

“…EB solution was prepared using Tris–HCl/NaCl buffer (pH 7.2). The test solution was added in aliquots of 2.5 μM concentrations to DNA–EB and the change in fluorescence intensities at 607 nm (520 nm excitation) was recorded …”

“…In addition, it should be noted that in the thiol form, there is an effective conjugation along the thiosemicarbazone skeleton thus giving rise to an efficient electron delocalization along the moiety. Also, the literature shows that nitrogen heterocyclic thiosemicarbazone‐based compounds exhibit a variety of medicinal properties such as anticancer, antitumour, antifungal, antibacterial, antiviral, antimalarial, antifilarial and anti‐HIV activities . In the recent past, our group has been keenly engaged in the study of the variable coordination behaviours of heterocyclic (both N and O) thiosemicarbazones and semicarbazones with diverse transition metals and biological properties of the resulting complexes.…”

“…Also, the literature shows that nitrogen heterocyclic thiosemicarbazone-based compounds exhibit a variety of medicinal properties such as anticancer, antitumour, antifungal, antibacterial, antiviral, antimalarial, antifilarial and anti-HIV activities. [20][21][22][23][24][25][26][27] In the recent past, our group has been keenly engaged in the study of the variable coordination behaviours of heterocyclic (both N and O) thiosemicarbazones [28][29][30][31][32] and semicarbazones [27,33] with diverse transition metals and biological properties of the resulting complexes. However, the structural and biological properties of 6-methyl-2-oxo-1,2-dihydroquinoline-3carbaldehyde-4(N)-substituted thiosemicarbazones have not been explored.…”