Synthesis, cytotoxic, anticancer and antimicrobial activities of some metal complexes of a novel tetradentate Schiff base ligand, (E)-3-((2-((E)-(1-(2-hydroxyphenyl)ethylidene)amino)ethyl)imino)-N-phenylbutanamide

Photocatalytic and Enhanced Biological Activities of Schiff Base Capped Fluorescent CdS Nanoparticles

In the present work, biocompatible CdS nanoparticles were synthesized using Schiff base ligand, 3-((2-(-(1-(2hydroxyphenyl)ethylidene)amino)ethyl)imino)-2-pentone, by a simple ultrasonic irradiation method. The structural, morphological, and optical properties were studied using XRD, SEM, TEM, UV-visible absorption, and photoluminescence (PL) spectra. The quantum confinement effect of the Schiff base capped CdS nanoparticles was confirmed by using UV-visible and PL spectrum analysis. This CdS nanoparticles were an effective photocatalyst for degrading rhodamine 6G and methylene blue with a 70% and 98% degradation capacity, respectively. Furthermore, the disc-diffusion method demonstrated that CdS nanoparticles inhibit G-positive bacteria and G-negative bacteria more effectively. These Schiff base capped CdS nanoparticles were taken for an in-vitro experiment with HeLa cells to exhibit the possibility of providing optical probes in biological applications and observed under a fluorescence microscope. In addition, MTT cell viability assays were carried out to investigate the cytotoxicity for 24 h. As a result of this study, 2.5 µg/ml doses of CdS nanoparticles are suitable for imaging and are effective in destroying HeLa cells. The present study suggests that the synthesized Schiff base capped CdS nanoparticles could be a potential photocatalyst, antibacterial agent, and biocompatible nanoparticle for bioimaging applications.

Spectroscopic Characterization and Biological Activity of Hesperetin Schiff Bases and Their Cu(II) Complexes

The three Schiff base ligands, derivatives of hesperetin, HHSB (N-[2,3-dihydro-5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)chromen-4-ylidene]isonicotinohydrazide), HIN (N-[2,3-dihydro-5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)chromen-4-ylidene]benzhydrazide) and HTSC (N-[2,3-dihydro-5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)chromen-4-ylidene]thiosemicarbazide) and their copper complexes, CuHHSB, CuHIN, and CuHTSC were designed, synthesized and analyzed in terms of their spectral characterization and the genotoxic activity. Their structures were established using several methods: elemental analysis, FT-IR, UV-Vis, EPR, and ESI-MS. Spectral data showed that in the acetate complexes the tested Schiff bases act as neutral tridentate ligand coordinating to the copper ion through two oxygen (or oxygen and sulphur) donor atoms and a nitrogen donor atom. EPR measurements indicate that in solution the complexes keep their structures with the ligands remaining bound to copper(II) in a tridentate fashion with (O^-, N, O_ket) or (O^-, N, S) donor set. The genotoxic activity of the compounds was tested against model tumour (HeLa and Caco-2) and normal (LLC-PK1) cell lines. In HeLa cells the genotoxicity for all tested compounds was noticed, for HHSB and CuHHSB was the highest, for HTSC and CuHTSC-the lowest. Generally, Cu complexes displayed lower genotoxicity to HeLa cells than ligands. In the case of Caco-2 cell line HHSB and HTSC induced the strongest breaks to DNA. On the other side, CuHHSB and CuHTSC induced the highest DNA damage against LLC-PK1.

Mononuclear and Tetranuclear Copper(II) Complexes Bearing Amino Acid Schiff Base Ligands: Structural Characterization and Catalytic Applications

Two new glycine-Schiff base copper(II) complexes were synthesized. Single crystal X-ray diffraction (SCXRD) allowed us to establish the structure of both complexes in the solid state. The glycine-Schiff base copper(II) complex derived from 2′-hydroxy-5′-nitroacetophenone showed a mononuclear hydrated structure, in which the Schiff base acted as a tridentate ligand, and the glycine-Schiff base copper(II) complex derived from 2′-hydroxy-5′-methylacetophenone showed a less common tetranuclear anhydrous metallocyclic structure, in which the Schiff base acted as a tetradentate ligand. In both compounds, copper(II) had a tetracoordinated square planar geometry. The results of vibrational, electronic, and paramagnetic spectroscopies, as well as thermal analysis, were consistent with the crystal structures. Both complexes were evaluated as catalysts in the olefin cyclopropanation by carbene transference, and both led to very high diastereoselectivity (greater than 98%).