A new tetradentate Schiff base ligand entitled as (L = (N²E, N^2′E)‐N¹, N^1′‐(ethane‐1,2‐diyl)bis(N2‐((E)‐3‐(2‐nitrophenyl)allylidene)ethane‐1,2‐diamine) and its six cadmium(II) complexes formulated as CdLX₂ in which X is Cl, Br, I, NO₃, NCS, or N₃ were synthesized under ultrasound irradiation and characterized by various physical and spectral techniques. Moreover, some complexes were also prepared in nanostructured dimensions confirmed by scanning electron microscopy (SEM), energy dispersive X‐ray analysis (EDXA), and X‐ray powder diffraction (XRPD) techniques and then were used as precursor for preparation of CdO nanoparticles via direct calcination at 600°C. As typical, the crystal structure of cadmium(II) nitrate complex was determined using single crystal X‐ray diffraction. Accordingly, it was found that [Cd(L)(NO₃)₂] complex crystallizes in the monoclinic space group P2₁/n with two independent molecules in the asymmetric unit with two coordination modes of nitrate anions. This complex has zero‐dimensional (0D) coordination supramolecular structure. Hirshfeld surface analyses suggested that H … O (49.5%), H … H (30.3%), and H … C (11.8%) intermolecular interactions are most considerable in the crystal packing. Computational studies of ligand structure leading to electrostatic potentials of the solid state geometry and some occupied molecular orbitals (HOMO, HOMO‐1, HOMO‐2, and HOMO‐5) prevailing the contribution of nitrogen lone pairs are also reported. Thermal behavior studies of the compounds under nitrogen atmosphere from room temperature to 900°C revealed that the ligand is completely decomposed without any residual whereas the complexes are decomposed via two to four thermal steps with trace amount of metallic cadmium as residue. Moreover, antibacterial and antifungal screening well showed that the complexes inhibit from the growth of the various bacteria and fungi more efficient than free ligand especially against Gram‐positive bacteria. DNA cleavage potentials of the compounds may be one of the reasons for their antimicrobial activity.

The enantiopure Schiff bases (R or S)-N-1-(phenyl)ethyl-2,4-X¹,X²-salicylaldimine (X¹, X² = Cl, Br, I) coordinate to copper(II) and provide pseudotetrahedral bis[(S or R)-N-1-(phenyl)ethyl-(2,4-X¹,X²-salicylaldiminato-κ²N,O)]-Δ/Λ-Cu(II) (Λ/Δ-Cu-R or Δ/Λ-Cu-S). An induced Λ and Δ-chirality at-metal centre has been launched along the C₂-axis of the molecule. Steric constraints brought by halogen substituents on the coordinating salicylal ring provide diastereoselectively Λ-Cu-R or Δ-Cu-S as major and Δ-Cu-R or Λ-Cu-S as minor diastereomers at solid-state, as evidenced by X-ray crystal structures and PXRD analyses. These results reveal inversion of induced chirality at-metal in comparison to the similar complexes without halogen substituents on the salicylal ring. Electronic circular dichroism (ECD) spectra show mirror-image relationships, confirming enantiomeric excess of the R or S-ligated complexes in solution. Comparisons of experimental and simulated ECD spectra suggest diastereomeric excess of Δ-Cu-R or Λ-Cu-S in solution which correspond to an inversion from the found solid-state Λ-Cu-R or Δ-Cu-S as major diastereomers. In addition, the optimized gas-phase structures also reveal Δ-Cu-R or Λ-Cu-S as slightly more stable than Λ-Cu-R or Δ-Cu-S. Thus, solid-state versus solution (or gas-phase) studies also indicate an interconversion of induced chirality (helicity inversion) at-metal from Λ-Cu-R or Δ-Cu-S to Δ-Cu-R or Λ-Cu-S. Thermal stability increases with the molecular weight of the complexes following Cl < ClBr < Br < I substituents. Hirshfeld surface analyses explore the strongest halogen (ortho)–halogen (para) interactions between two molecules in Λ-Cu-R3 or Δ-Cu-S3 at a distance shorter than the sum of the van der Waals radii of the two iodine atoms, provide a brilliant red spot on the d_norm surfaces. EPR spectra along with simulation suggest an axial symmetry with g_z > g_x,y > 2.0 and values for g_z/A_z ≥ 135 cm indicate pseudotetrahedral geometry for the complexes.