Synthesis, structure, and photoluminescent and electroluminescent properties of zinc(II) complexes with bidentate azomethine ligands

Characterization of a New Hybrid Compound (C3H8N6)2ZnCl4·2Cl: X-ray Structure, Hirshfeld Surface, Vibrational, Thermal Stability, Dielectric Relaxation, and Electrical Conductivity

A novel organic-inorganic material (C3H8N6)2ZnCl4·2Cl was synthesized via a slow evaporation approach and subjected to extensive characterization. Techniques involving X-ray diffraction, SEM/EDX, Hirshfeld surface examination, IR/Raman spectroscopy, thermal behavior (TG/DTG/SDTA and DSC), and electric and dielectric studies were applied. Examination of the crystal structure reveals that the synthesized material adopts a monoclinic system, particularly belonging to the P21/c space group with unit cell parameters a = 11.7274(3) Å, b = 6.2155(2) Å, c = 25.7877(8) Å, β = 94.27(1)°, V = 1874.50(4) Å3, and Z = 4. Purity confirmation was established via powder X-ray diffraction analysis. Composition verification was conducted using semiquantitative EDXS analysis. The asymmetric unit comprises isolated tetrachlorozincate [ZnCl4]2- anions, two (C3H8N6)2+ organic cations, and two free chlorine atoms, forming a 0D anionic network. N-H···Cl and N-H···N hydrogen bonding combined to form a 2D hydrogen-bonded network, maintaining crystal stability. Hirshfeld surface analysis elucidated intermolecular interactions, supported by 2D fingerprint plots. IR and Raman spectra analysis corroborated compound characteristics at room temperature. Thermal analysis revealed two phase transitions at 343 and 358 K, consistent with dielectric studies. Impedance spectroscopy highlighted the compound's electrical properties, confirming thermal transitions. Conductivity studies exhibited an Arrhenius behavior. Frequency-dependent dielectric constant variations and modulus studies underscored grain and grain boundary effects, confirming the effective protonic conduction in the material.

Synthesis, Structure, Spectral-Luminescent Properties, and Biological Activity of Chlorine-Substituted N-[2-(Phenyliminomethyl)phenyl]-4-methylbenzenesulfamide and Their Zinc(II) Complexes

New azomethine compounds of 2-(N-tosylamino)benzaldehyde or 5-chloro-2-(N-tosylamino)benzaldehyde and the corresponding chlorine-substituted anilines, zinc(II) complexes based on them have been synthesized. The structures of azomethines and their complexes were determined by elemental analysis, IR, ¹H NMR, X-ray spectroscopy, and X-ray diffraction. It is found that all ZnL₂ complexes have a tetrahedral structure according to XAFS and X-ray diffraction data. The photoluminescent properties of azomethines and zinc complexes in methylene chloride solution and in solid form have been studied. It is shown that the photoluminescence quantum yields of solid samples of the complexes are an order of magnitude higher compared to the solutions and range from 11.34% to 48.3%. The thermal properties of Zn(II) complexes were determined by thermal gravimetric analysis (TGA) and differential scanning calorimetry. The TGA curves of all the compounds suggest their high thermal stability up to temperatures higher than 290 °C. The electrochemical properties of all complexes were investigated by the cyclic voltammetry method. The multilayered devices ITO/PEDOT:PSS/NPD/Zn complex/ TPBI/LiF/Al with wide electroluminescence (EL) color range spanning the range from bluish-green (494 nm) to green (533 nm) and the high values of brightness, current and power efficiency were fabricated. The biological activity of azomethines and zinc complexes has been studied. In the case of complexes, the protistocidal activity of the zinc complex with azomethine of 5-chloro-2-(N-tosylamino)benzaldehyde with 4-chloroaniline was two times higher than the activity of the reference drug toltrazuril.