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.

Quinoline based Schiff base 6-methyl-2-oxo-1,2-dihydro-quinoline-3carboxaldehyde-4(N)-phenylsemicarbazone (6MPS) sensor has been developed for selective sensing of methionine and aspartic acid in aqueous medium through selective detection of copper ion as “on-off-on” type....

A series of copper(II) complexes containing 6‐methyl‐2‐oxo‐1,2‐dihydroquinoline‐3‐carboxaldehyde‐derived Schiff bases have been synthesized and characterised using various analytical and spectroscopic techniques. X‐ray crystallographic analysis confirmed the true coordinating nature of ligands with copper ion. The ligands exhibited ONS tridentate neutral and monobasic coordination. The spectroscopic results evidenced the interaction of the ligands and their copper(II) complexes with nucleic acid/serum albumin. Further, the complexes showed significant activity against human skin cancer cell line (A431) and less toxicity against human keratinocyte cell line (HaCaT). Acridine orange/propidium iodide dual staining studies indicated that the major cause of A431 cell death was through necrosis. By comparing the biological activity of all the ligands, Cu(II) complexes and standard (cisplatin), complex [Cu(H‐6MOQtsc‐Ph)(H2O)]⋅NO3 (4) exhibited better activity than others, the activity being arranged as follows: 4 > 1 > cisplatin > 3 > 2.

A highly sensitive and selective “on–off–on” chemosensor for aspartic acid in aqueous solution was established. In vitro live cell imaging against MCF 7 cells and in vivo imaging using C. elegans were successfully demonstrated.

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