A series of copper (II) (1 and 3) and cobalt (II/III) (2, 4 and 5) complexes comprising different imino-phenolate ligands DCH, DTH and DBH 2 (where DCH = 2,4-dichloro-6-((mesitylimino)methyl)phenol, DTH = 2,4-di-tert-butyl-6-((mesitylimino)methyl) phenol and DBH 2 = 2,4-dibromo-6-((mesitylimino) methyl)phenol) have been prepared with excellent yield and high purity. By utilizing different spectroscopic tools such as UV-visible, electrospray ionization (ESI)-mass, Fourier-transform infrared (FTIR) spectrometry and elemental analysis, the prepared complexes (1-5) were thoroughly characterized. The molecular structure of the synthesized complexes was ascertained by using single-crystal X-ray diffraction studies (SCXRDs). The experiment reveals that Complexes 1-5 bind to calf thymus DNA (CT-DNA) through non-intercalative way with good interacting abilities. However, 1-5 are excellent quenchers of the fluorescence intensity of bovine serum albumin (BSA) following the static pathway. Additionally, they had shown remarkable cytotoxic potential against MCF-7 (mammary gland adenocarcinoma) and A549 (lung adenocarcinoma) cell lines. The IC 50 values associated with these complexes were much lower than the conventional drug cisplatin. Apoptosis-induced cell death was confirmed from the DNA fragmentation studies and Hoechst 33342 staining. The 2 0 ,7 0-dichlorofluorescein diacetate (DCFDA) assay indicates that the complex mediated reactive oxygen species (ROS) generation is accountable for governing the apoptosis mechanism via oxidative cell distress. Apart from these studies, by carrying out density functional theory (DFT) method, highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gap calculations and optimized structures of the synthesized complexes were accomplished.

A unique hexanuclear zinc(II) (1) and two mononuclear copper(II) (2 and 3) complexes anchored with imino phenol ligand HL 1 and HL 2 were synthesized with good yield and purity (where HL 1 = 4-tert-butyl-2,6-bis((mesitylimino) methylphenol and HL 2 = 5-tert-butyl-2-hydroxy-3-((mesitylimino)methyl) benzaldehyde). These complexes were characterized by utilizing various spectroscopic protocols like NMR, FTIR, UV as well as ESI-Mass spectrometry, elemental analysis and single crystal X-ray diffraction studies. Their potential to bind calf thymus DNA (CT-DNA) was tested utilizing different techniques such as UV-visible and fluorescence spectroscopy. The experiment implies that they interact with CT-DNA via non-intercalative mode with moderate capabilities (K b~1 0 4 M −1 ). On the other hand, these complexes have high capabilities to quench the fluorescence of bovine serum albumin (BSA) following the static pathway. In addition, they are active catalysts for the oxidation reaction of 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylquinone (3,5-DTBQ) under aerobic condition. From the recorded EPR signals of all complexes, it has been concluded that the oxidation reaction proceeds via ligand oriented radical pathway instead of metal based redox participation. Kinetic studies using 1-3 indicate that it follows Michaelis-Menten type of equation with moderate to high turnover number (k cat ). Apart from these aspects, complexes 1-3 were screened for their cytotoxic behavior towards HeLa cells (human cervical carcinoma) and found quite active with comparable IC 50 values to cisplatin.

Herein, a new type of Schiff base ligand, HSL2 (where HSL2=2,2,7,7‐tetramethyltetrahydro‐3aH‐bis[1,3]dioxolo[4,5‐b:4′,5′‐d]pyran‐5‐yl) methyl‐4‐(3,5‐dichloro‐2‐hydroxybenzylidene amino)benzoate) anchored with a monosaccharide unit have been synthesized and characterized by FT‐IR, 1H NMR, and ESI‐MS. The ligand are chelated to metal ions Zn(II) (1), Cu(II) (2), and Mn(II) (3) to from square planar/tetrahedral or octahedral complexes. The DFT studies are carried out to optimize the shapes of the compounds. Moreover, Cu(II) and Mn(II) complexes were also characterized by EPR spectroscopy. The cytotoxicity of the complexes was screened towards three different cell lines A549 (lung cancer), HeLa (cervical cancer), and HT29 (colorectal cancer). These complexes exhibited significant cytotoxicity against three aforementioned cell lines and IC50 values are found in the range of 19.77–23 μM on HeLa cells, 9.42–12.25 μM on A549 cells and 8.84–16 μM on HT29 cells. The cell death mechanism was also studied by employing DNA fragmentation, Hoechst 33342 nuclear staining, and Acridine orange/ Ethidium Bromide (AO/EB) assay. In addition, ROS generation was also evaluated with these metal complexes.

Green synthesis of silver nanoparticles (AgNPs) was carried out using aqueous bark extract of Shorea robusta(Sal tree) as the reducing and capping agent. AgNPs were characterized using modern characterization tools like UV-Vis, PXRD, FT-IR, SEM, and HR-TEM. The catalytic application of the prepared AgNPs in three-component coupling reaction of aldehyde, malononitrile, and cyclic enamino ketone resulted in good to excellent yields of hexahydroquinoline derivatives. Moreover, the catalyst can be recycled up to 5 times without compromising too much yield. The mechanistic pathway was investigated employing GC-Mass spectroscopy and supported through the Density Functional Theory (DFT) calculations. A two-step mechanism has been proposed for the coupling reaction, and the presence of electron-withdrawing group in the aldehyde component is found to be more favorable than electron-releasing one in terms of yield with lesser time.