Four‐, five‐ and six‐coordinated transition metal complexes based on naphthalimide Schiff base ligands: Synthesis, crystal structure and properties

Abstract

Two bidentate Schiff base ligands (HL 1 = N-n-butyl-4-[(E)-2-(((2-aminoethyl)imino) (3) have been synthesized and characterized. Single-crystal X-ray structure analysis reveals that complex 1 has a four-coordinated square geometry, while complex 2 is a five-coordinated square pyramidal structure and complex 3 is a distorted six-coordinated octahedral structure. Cyclic voltammograms of 1 indicate an irreversible Cu 2+ /Cu + couple. In vitro antioxidant activity assay demonstrates that the ligands and the two complexes 1 and 3 display high scavenging activity against hydroxyl (HO • ) and superoxide (O 2 −• ) radicals. Moreover, the fluorescence properties of the ligands and complexes 1-3 were studied in the solid state. Metal-mediated enhancement is observed in 2, whereas metal-mediated fluorescence quenching occurs with 1 and 3.

Construction of naphthalene diimide-based cadmium complexes and their application in iodine adsorption, photochromism, and photocatalysis

“…55 In addition, NDI derivatives with the auxiliary chromic groups can be easily grafted to fine-tune absorption and emission wavelengths. 56 Therefore, it has a wide range of applications in photochromism, 57–59 fluorescence, 60,61 and other aspects. Charge transfer (CT) and photoinduced intermolecular electron transfer (PIET) are two pivotal internal electron behaviors between electron donors (EDs) and electron acceptors (EAs) in organic–inorganic hybrid photochromic systems, which largely determine the photophysical and photochemical properties.…”

Recent advances in anticancer ruthenium Schiff base complexes

“…Nevertheless, the precise mechanisms of action of the Schiff bases are not yet fully understood and, therefore, continue to deserve further investigations. [51,52] Owing to the pharmaceutical significance of Schiff bases, recent design of Ru(II) anticancer compounds takes into consideration the use of Schiff bases to improve the efficacy of the compounds. Schiff base ligands contain bidentate N,O-and tridentate N,O,Odonor groups, and so on, which can be designed to form mono-, di-and trimeric, one-, two-and three-dimensional complexes together with other coordinating moieties such as thiocyanate and carboxylic groups acting as either bridging or terminal ligands.…”

“…Nevertheless, the precise mechanisms of action of the Schiff bases are not yet fully understood and, therefore, continue to deserve further investigations. [ 51,52 ]…”

Some divalent metal(II) complexes of salicylaldehyde‐derived Schiff bases: Synthesis, spectroscopic characterization, antimicrobial and in vitro anticancer studies

“…Schiff base transition metal complexes have attracted much attention in the curative area due to their distinctive ligational behaviour, significant physicochemical properties and effective applications as new medicinal agents. A range of biological activities like DNA binding, antimicrobial, anticancer, antitubercular, antiangionesis, antiviral, antiparasitic, anti‐inflammatory, antipyretic, anti‐HIV and anticonvulsant activities and catalysis of various reactions, production of amino acids and drug interactions with biomolecules are also exhibited by Schiff base transition metal complexes. These biological applications are influenced greatly by the structure of the molecule, coordination number as well as the substituents bound on the Schiff bases …”