Synthesis, characterization, structural study and antibacterial activity of the Schiff bases derived from sulfanilamides and related copper(II) complexes

Effects of changing ions on the crystal design, non-covalent interactions, antimicrobial activity, and molecular docking of Cu(II) complexes with a pyridoxal-hydrazone ligand

The present work reports the influence of the presence of different ions (Cl-, Br-, NO3 -, or SO4 2-) on the formation and proprieties of Cu(II) complexes with pyridoxal-benzoylhydrazone (PLBHZ). Four new complexes were successfully synthesized, [CuCl2(PLBHZ)] (1), [CuBr2(PLBHZ)] (2), [CuCl(PLBHZ)H2O]⋅NO3⋅H2O (3), and [CuSO4(PLBHZ)H2O]⋅3H2O (4), and characterized by spectroscopic and physicochemical methods. A single-crystal X-ray study reveals the Schiff base coordinated to the metal center tridentate by the ONS-donor system, resulting in distorted square pyramidal coordination geometries. Noncovalent interactions were investigated by 3D Hirshfeld surface analysis by the d norm function, 2D fingerprint plots, and full interaction maps. The ion exchange is important in forming three-dimensional networks with π⋅⋅⋅π stacking interactions and intermolecular hydrogen bonds. The in vitro biological activity of the free ligand and metal complexes was evaluated against Gram-positive and Gram-negative bacterial strains and the free pyridoxal-hydrazone ligand showed higher activity than their Cu(II) complexes. Molecular docking was used to predict the inhibitory activity of the ligand and complexes against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria.

4-Bromo-2-[({2-[(2-hy-droxy-eth-yl)amino]-eth-yl}imino)-meth-yl]phenol

The new title Schiff base compound, C11H15BrN2O2, crystallizes in the monoclinic space group P21 with two independent mol-ecules in the asymmetric unit. It was prepared by the condensation reaction of 5-bromo-2-hy-droxy-benzaldehyde and amino-ethyl-ethano-lamine. There is an intra-molecular O-H⋯N hydrogen bond with an S(6) ring motif. Moreover, there are inter-molecular C-H⋯N, C-H⋯O and Br⋯O inter-actions in the crystal structure of the title compound.

Crystal structure of 2-((1H-benzo[d]imidazol-2-ylimino)methyl)-4,6-di-tert-butylphenol, C22H27N3O

C22H27N3O, monoclinic, P21/c (no. 14), a = 18.4984(4) Å, b = 11.4221(3) Å, c = 9.79600(19) Å, β = 90.9652(19)°, V = 2069.51(8) Å3, Z = 4, R gt(F) = 0.0605, wR ref(F 2) = 0.1773, T = 293(2) K.

Catalytic intramolecular hydroamination of aminoallenes using titanium complexes of chiral, tridentate, dianionic imine-diol ligands

Alkylation of d- or l-phenylalanine or valine alkyl esters was carried out using methyl or phenyl Grignard reagents. Subsequent condensation with salicylaldehyde, 3,5-di-tert-butylsalicylaldehyde, or 5-fluorosalicylaldehyde formed tridentate, X2L type, Schiff base ligands. Chiral shift NMR confirmed retention of stereochemistry during synthesis. X-ray crystal structures of four of the ligands show either inter- or intramolecular hydrogen bonding interactions. The ligands coordinate to the titanium reagents Ti(NMe2)4 or TiCl(NMe2)3 by protonolysis and displacement of two equivalents of HNMe2. The crystal structure of one example of Ti(X2L)Cl(NMe2) was determined and the complex has a distorted square pyramidal geometry with an axial NMe2 ligand. The bis-dimethylamide complexes are active catalysts for the ring closing hydroamination of di- and trisubstituted aminoallenes. The reaction of hepta-4,5-dienylamine at 135 °C with 5 mol% catalyst gives a mixture of 6-ethyl-2,3,4,5-tetrahydropyridine (40-72%) and both Z- and E-2-propenyl-pyrrolidine (25-52%). The ring closing reaction of 6-methyl-hepta-4,5-dienylamine at 135 °C with 5 mol% catalyst gives exclusively 2-(2-methyl-propenyl)-pyrrolidine. The pyrrolidine products are obtained with enantiomeric excesses up to 17%.