New aspects of the Ni(II)-salophen complex and salophen ligand precursor were found during deep electrochemical and optical characterization, as well as biological studies for new pharmacological applications. Physicochemical and spectroscopic methods (¹H- and ¹³C-NMR, FT-IR and UV-Vis, electrospray ionization mass spectroscopy, thermogravimetric analysis, and molar conductance measurements) were also used to prove that the salophen ligand acts as a tetradentate and coordinates to the central metal through nitrogen and oxygen atoms. The electrochemical behavior of the free Schiff salophen ligand (H₂L) and its Ni(II) complex (Ni(II)L) was deeply studied in tetrabutylammonium perchlorate solutions in acetonitrile via CV, DPV, and RDE. Blue films on the surfaces of the electrodes as a result of the electropolymerization processes were put in evidence and characterized via CV and DPV. (H₂L) and Ni(II)L complexes were tested for their antimicrobial, antifungal, and antioxidant activity, showing good antimicrobial and antifungal activity against several bacteria and fungi.

The title compound, [Cd₂(C₇H₁₀NS₂)₄], is a neutral dinuclear cadmium(II) complex bearing four bisN,N-diallyldithiocarbamate ligands coordinating to two Cd^IIcations. In each of the monomeric subunits, there are four S atoms of two dithiocarbamate ligands [Cd—S = 2.5558 (3), 2.8016 (3), 2.6050 (3) and 2.5709 (3) Å] that coordinate to one Cd^IIatom in a bidentate mode. The dimers are located over an inversion centre bridged by two additional bridging Cd—S bonds [2.6021 (3) Å], leading to a substantial distortion of the geometry of the monomeric subunit from the expected square-planar geometry. The five-coordinate environment around each of the Cd^IIions in the dimer is best described as substantially tetragonally distorted square pyramidal. The dithiocarbamate groups are themselves planar and are also coplanar with the Cd^IIions. The negative charge on these groups is delocalized by resonance across the S atoms bound to the Cd^IIcation. This delocalization of the π electrons in the dithiocarbamate groups also extends to the C—N bonds as they reveal significant double bond character [C—N = 1.3213 (16) and 1.3333 (15) Å].

The crystal structure of the title compound {systematic name: [bis(prop-2-en-1-yl)carbamodithioato-κ ² S , S ′](2-methylquinoline-κ N )zinc(II)}, [Zn(C ₇ H ₁₀ NS ₂ ) ₂ (C ₁₀ H ₉ N)] the heteroleptic complex reveals supramolecular dimers established by π–π interactions between adjacent quinaldine units with a centroid–centroid distance of 3.672 (2) Å. The compound crystallizes in the triclinic crystal system, space group P 1 , with the Zn ^II atom exhibiting a trigonal–bipyramidal geometry.

Tetrahydroacridines arouse particular interest due to the potential possibilities of application in the medical field and protection against corrosion. Bis-tetrahydroacridines were newly synthesized by Pfitzinger condensation of 5,5′-(ethane-1,2-diyl) diindoline-2,3-dione with several cyclanones. NMR, MS, and FT-IR were used to prove their molecular structure. In addition, a computer-aided study was performed for the lowest energy conformers of each structure, in vacuum conditions, at ground state using DFT models to assess their electronic properties. UV–Vis and voltammetric methods (cyclic voltammetry, differential pulse voltammetry, and rotating disk electrode voltammetry) were used to investigate their optical and electrochemical properties. The results obtained for these π-conjugated heteroaromatic compounds lead to the conclusion that they have real potential in applications in different fields such as pharmaceuticals and especially as corrosion inhibitors.