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

New Zn(II) complexes of bidentate Schiff base ligands were synthesized and characterized by 1H NMR, IR spectroscopy, and elemental analysis. The single-crystal X-ray diffraction study revealed that all compounds can be represented as mononuclear zinc(II) complexes with two bidentate organic ligands coordinated to the central metal atom by two oxygen and two nitrogen atoms. The photophysical properties of the complexes were investigated by UV–vis and photoluminescence spectroscopy in dimethyl sulfoxide (DMSO) solutions. It was found that the positions of maxima of the long-wavelength absorption bands and photoluminescence depend strongly on the substituent in the aldehyde and amine fragments. The nature of the bands of electronic absorption spectra in DMSO solutions was interpreted using the results of quantum chemical calculations in the time-dependent density functional theory (TD-DFT) approximation. The light emission performance of the complexes in organic light-emitting diodes was investigated. The electroluminescence (EL) spectra maxima of all three complexes are located in the visible range from 470 to 550 nm. The absence of additional spectral maxima or shoulders in the EL bands means that neither exciplex nor excimer states form, and the observed EL bands are due to the intrinsic radiation of the zinc(II) complexes. EQEs were measured for these three complexes. The maximum value, close to 3%, was obtained in the case of a structure with a maximal brightness of 8000 cd m−2 at 17 V. © 2020 John Wiley & Sons, Ltd