Mononuclear zinc(II), cadmium(II), cobalt(III) and di-nuclear nickel(II) complexes of a 14pi electron diimine ligand: Syntheses, structures, photoluminescence and DFT investigations

摘要: Abstract Three types of fluorescent coordination complexes an unsymmetrical diimine ligand (LNNOH) with conjugated 14π electrons (14πe) are reported [LNNOH = (E)-2-((phenyl(pyridin-2-yl)methylene) amino)phenol]. The are: [M(LNNO−)X] [M = Zn, X = Cl, 1; M = Zn, X = Br, 2; M = Cd, 3], [Co(LNNO−)2]Cl, [4]Cl and [Ni2(LNNOH)2(LNNO−)2]Cl2, [5]Cl2. were substantiated by elemental analyses, IR, 1H NMR, mass UV–Vis spectra including the single crystal X-ray structure determinations [4]Cl·H2O [5]Cl2·2H2O. Complexes 1–3 brightly in fluid solutions (CH2Cl2: 1, λex = 475, 507 nm, λem = 520, 551 nm, Φ = 0.037, τav = 2.6 ns; 2, λex = 474, λem = 519, 552 nm, Φ = 0.027, τav = 2.4 ns; 3, λem = 518, Φ = 0.01, τav = 2.0 ns; [4]Cl, λex = 472, 505 nm, 551, 601 nm, Φ = 0.06, τav = 3.9 ns) while [5]Cl2 is weakly emissive 506 nm, 557, 595 nm, Φ = 0.002, τav = 1.9 ns). Variable temperature magnetic measurement Mulliken atomic spin densities obtained from unrestricted density functional theory (DFT) calculation on [5]2+ cation, consistent existence interactive (J = +2.318) two Ni(II) ions. Time dependent (TD) DFT calculations 1 [4]+ authenticated intra-ligand πphenolato → πdiimine∗ transitions for both intra- inter-ligand as origins excitations.