Synthesis, structures and magnetic properties of copper (II) and cobalt (II) complexes containing pyridyl-substituted nitronyl nitroxide and 3,5-dinitrobenzoate

Biological Activity of Complexes Involving Nitro-Containing Ligands and Crystallographic-Theoretical Description of 3,5-DNB Complexes

Drug resistance in infectious diseases developed by bacteria and fungi is an important issue since it is necessary to further develop novel compounds with biological activity that counteract this problem. In addition, new pharmaceutical compounds with lower secondary effects to treat cancer are needed. Coordination compounds appear to be accessible and promising alternatives aiming to overcome these problems. In this review, we summarize the recent literature on coordination compounds based on nitrobenzoic acid (NBA) as a ligand, its derivatives, and other nitro-containing ligands, which are widely employed owing to their versatility. Additionally, an analysis of crystallographic data is presented, unraveling the coordination preferences and the most effective crystallization methods to grow crystals of good quality. This underscores the significance of elucidating crystalline structures and utilizing computational calculations to deepen the comprehension of the electronic properties of coordination complexes.

Influence of the Lewis basicity hardness of crystallization solvents on the coordination sphere of the complex [Co(3,5-dinitrobenzoate-O,O′)2]: crystallographic and theoretical analysis

Crystal growth of [Co(DNB)2] in different solvents is a thermodynamic process favored by ΔErecrys (kcal mol−1) where mono/trinuclear molecules are obtained. Closeness of HOMO orbitals of solvents to the SOMOs orbitals of Co(ii) ions guide the process.

Intermolecular interaction energies and magnetic properties of spin-isolated multinuclear CuII complexes

Dinuclear Cu^II complexes with 3,5-dinitrobenzoates and 2,2'-bipyridine (2) or 1,10-phenanthroline (3) were synthesized and characterized. A complete energy framework analysis using the HF/3-21G energy model was performed which found that dispersion forces and C-H...O interactions are responsible for the crystal structure features. The magnetic properties of the complexes show a weak magnetic exchange between spins, resulting in low exchange constants of -2.72 (1) cm^-1 and -1.10 (1) cm^-1 for complexes (2) and (3), respectively. This results from the low overlap between magnetic orbitals induced by 3,5-dinitrobenzoate bridges and the arrangement of the magnetic orbitals. Consequently, the dinuclear complexes (2) and (3) behave as spin-isolated multinuclear Cu^II species in contrast to the trinuclear complex with similar ligands.

Inhibition of C. albicans Dimorphic Switch by Cobalt(II) Complexes with Ligands Derived from Pyrazoles and Dinitrobenzoate: Synthesis, Characterization and Biological Activity

Seven cobalt(II) complexes of pyrazole derivatives and dinitrobenzoate ligands were synthesized and characterized. The single-crystal X-ray diffraction structure was determined for one of the ligands and one of the complexes. The analysis and spectral data showed that all the cobalt complexes had octahedral geometries, which was supported by DFT calculations. The complexes and their free ligands were evaluated against fungal strains of Candida albicans and emerging non-albicans species and epimastigotes of Trypanosoma cruzi. We obtained antifungal activity with a minimum inhibitory concentration (MIC) ranging from 31.3 to 250 µg mL-1. The complexes were more active against C. krusei, showing MIC values between 31.25 and 62.5 µg mL-1. In addition, some ligands (L1-L6) and complexes (5 and Co(OAc)2 · 4H2O) significantly reduced the yeast to hypha transition of C. albicans at 500 µg mL-1 (inhibition ranging from 30 to 54%). Finally, the complexes and ligands did not present trypanocidal activity and were not toxic to Vero cells. Our results suggest that complexes of cobalt(II) with ligands derived from pyrazoles and dinitrobenzoate may be an attractive alternative for the treatment of diseases caused by fungi, especially because they target one of the most important virulence factors of C. albicans.

Diaqua-bis-(benzoato-κO)bis-[4,4,5,5-tetra-methyl-2-(pyridin-4-yl-κN)imidazoline-1-oxyl 3-oxide]cobalt(II)

The title compound, [Co(C(7)H(5)O(2))(2)(C(12)H(16)N(3)O(2))(2)(H(2)O)(2)], was obtained from a conventional solvent evaporation method. The complex mol-ecule is centrosymmetric, so pairs of equivalent ligands lie trans to each other in a slightly distorted octa-hedral CoN(2)O(4) geometry. The Co(II) ion is coordinated by the pyridine N atoms from NITpPy ligands [NITpPy is 4,4,5,5-tetra-methyl-2-(pyridin-4-yl)imidazoline-1-oxyl 3-oxide), water O atoms and two monodentate benzoate O atoms. The complex mol-ecules are connected by O-H⋯O hydrogen bonds between water mol-ecules and benzoate ligands, forming chains parallel to [100]. π-π stacking inter-actions between the benzoate ligands with centroid-centroid distances of 3.752 (2) Å connect the chains into layers parallel to (10-1).

Bis(2,2'-bipyridyl dioxide-κN,N')bis-(tricyano-methanido)cobalt(II) dihydrate

In the title compound, [Co(C₄N₃)₂(C₁₀H₈N₂O₂)]·2H₂O, a novel tricyano­methanide complex, the Co^II atom is located on an inversion center and has a distorted octa­hedral coordination with two 2,2′-bipyridyl dioxide (dpdo) mol­ecules and two trans tricyano­methanide (tcm) anions. The equatorial plane is formed by the four O atoms of the two chelating dpdo ligands, with one N atom of each of the two tcm ligands occupying an apical position. There is a disordered solvent water mol­ecule in the asymmetric unit (occupancy ratio 0.63:0.37). These water mol­ecules result in the formation of O—H⋯O and O—H⋯N hydrogen bonds, building a layer parallel to (100). The layers are linked by C—H⋯N hydrogen-bonding inter­actions, leading to a three-dimensional network.