Absorption and luminescence spectra of 5-aryl-3-methyl-1,2,4-oxadiazoles and their chelate complexes with Zinc(II) and copper(II)

Synthesis, crystal structures, fluorescence, electrochemiluminescent properties, and Hirshfeld surface analysis of four Cu/Mn Schiff‐basecomplexes

“…For 3 and 4 , lower fluorescence intensity and redshift relative to HL 2 ligand probably originated from the paramagnetic influence of Cu II or Mn II cations which are d 9 and d 5 ions, respectively. [ 42 ] By comparing the fluorescence intensity of 1 and 2 or 3 and 4 , we found that the fluorescence intensity of compounds 1 or 3 was lower than that of compounds 2 or 4 constructed with the same ligand, which can be attributed to the electronegativity of the substituents and also the electron density of the ligand as the electronegativity of chlorine is greater than that of bromine. As a result, the electron density of ligand HL 1 was lower than that of ligand HL 2 , which is harmful to the ligand‐to‐metal charge transfer.…”

“…Compared to the free ligand HL 1 , with 57 and 44 nm red‐shifted for 1 and 2 , respectively, the emission at 527 and 514 nm and lower fluorescence intensity of the compounds 1 and 2 probably originated from the paramagnetic influence of Cu II or Mn II cations which are d 9 and d 5 ions, respectively. [ 42 ]…”

“…Compared to the free ligand HL 1 , with 57 and 44 nm red-shifted for 1 and 2, respectively, the emission at 527 and 514 nm and lower fluorescence intensity of the compounds 1 and 2 probably originated from the paramagnetic influence of Cu II or Mn II cations which are d 9 and d 5 ions, respectively. [42] As shown in Figure 7b, upon photoexcitation at 450 nm, the free HL 2 ligand exhibited a green luminescent emission peak at 512 nm predominantly also assigned to π-π* transition fluorescence. At the same 450 nm photoexcitation, 3 and 4 exhibited also a green luminescent emission peak at 519 and 522 nm.…”

Spectral Luminescent Properties of 3-[5-(4-Methoxyphenyl)-1,3,4-oxadiazol-2-yl]acrylic Acid and Its Complex with Zn(II)

“…Chelate complexes with oxadiazol ligands are widely used as metal complex luminophors [7,8] as well as emission and electron-transport materials for organic and light emitting diodes (OLED) [9].…”