A Blue Luminescent Starburst Molecule and Its Orange Luminescent Trinuclear PdII Complex: 1,3,5-tris(7-azaindol-1-yl)benzene (tabH) and [PdII3(tab)2Cl4]
Abstract:Alone, tabH luminesces blue (tabH=1,3,5‐tris(N‐7‐azaindolyl)benzene) but orange when complexed to PdII ions. Both the tabH ligand and the trinuclear complex 1 have been synthesized and characterized. The tab ligands in 1 function both as a chelating ligand and a bridging ligand, which leads to a linear arrangement of the three PdII ions.
“…The HIBA ligand was prepared by the method similar to that reported in ref. [13]. FT-IR spectra were recorded on a Bruker Vector22 FT-IR spectrophotometer using KBr disks.…”
Two novel interpenetrated coordination polymers, [Zn(IBA) 2 ] n (1) and {[Cd(IBA) 2 (H 2 O)]·4H 2 O} n (2), have been synthesized by using 4-imidazole-benzoic acid (HIBA) as ligand under hydrothermal conditions. Complex 1 crystallizes in a chiral space group and has a two-fold interpenetrated 2D network structure with (4,4) topology, while complex 2 is a 3D porous dia network with four nets interpenetrating each other. The SHG activity of 1 and the photoluminescent property of 2 have been investigated.coordination polymer, interpenetration, crystal structure, photoluminescence property
“…According to the literature, the luminescence emission from Pd complexes can be attributed to ligand-localized (LC) states due to intraligand pp* transitions of the ligands, MLCT (monomeric) or MMLCT (dimeric) transitions. [50][51][52][53][54] The emission spectra were obtained using excitation wavelengths from the UV-Vis data. The measurements in dichloromethane were performed using excitation and emission slits of 5.0 nm/5.0 nm, respectively to the monomeric complexes.…”
The cyclopalladation of the 4-aryl-2,1,3-benzothiadiazoles 1a-c with palladium acetate in acetic acid afforded the novel dimeric complexes 2a-c in good yields. These were then converted into the monomeric pyridine-, chloro-coordinated cyclometallated complexes 3a-c through reaction with lithium chloride in acetone and then pyridine in dichloromethane. All complexes were fully characterized by means of NMR, IR and elemental analysis. The X-ray structure of complex 2c revealed that it presents transoid geometry, whereas the X-ray structure of 3c shows that the pyridine ligand and the thiazole ring are mutually trans. Photophysical properties were investigated by means of UV-Vis absorption and fluorescence emission in solution. Solid-state diffuse reflectance UV-Vis spectra (DRUV) were also applied in order to better characterize the complexes photophysics in the solid state. All complexes present intense absorption at around 300 nm (λ(1)) via(1)LC transitions located in BTD ligands, and additional low energy absorption bands, higher than 450 nm (λ(2)) of (1)MLCT character. The complexes are fluorescent in solution at room temperature, where two emission bands could be observed, a high energy band (excitation @ λ(1)) ascribed to the ligand emission and an additional red shifted low intense band (excitation @ λ(2)) due to the complex emission.
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