Iron(III) Metallacryptand and Metallacryptate Assemblies Derived from Aroylbis(<i>N</i>,<i>N</i>‑diethylthioureas)

The reaction of isophthaloylbis­(<i>N</i>,<i>N</i>-diethyl­thiourea), H₂L¹, with FeCl₃·6H₂O gives the dinuclear tris-complex [Fe₂(L¹)₃] (<b>5</b>), possessing a cryptand-like structure. A similar reaction with the ligand 2,6-dipicolinoylbis­(<i>N</i>,<i>N</i>-diethylthiourea), H₂L², however, results in the formation of the anionic, mononuclear Fe­(III) complex [Fe­(L²)₂]⁻ (<b>6</b>), which could be isolated as its “Tl⁺ salt” by the subsequent addition of Tl­(NO₃). A tighter view to the solid state structure of the obtained product, however, characterizes compound <b>6</b> as a one-dimensional coordination polymer, in which four-coordinate Tl⁺ ions connect the {[Fe­(L²)₂]⁻} units to infinite chains. When Fe³⁺ ions and Tl⁺ ions are added to H₂L² simultaneously in a one-pot reaction, a different product is obtained: a cationic trinuclear complex of the composition {M⊂[Fe₂(L²)₃]}⁺. It has been isolated as a PF₆^– salt and represents a {2}-metallacryptate with a nine-coordinate Tl⁺ ion in the central void. Structurally related products of the compositions {M⊂[Fe₂(L²)₃]}­(PF₆) (M = Na⁺, K⁺, Rb⁺) (<b>8</b>(PF₆)) could be isolated from analogous reactions with alkaline salts instead of Tl­(NO₃). {2}-Metallacryptates with larger central voids were synthesized with the ether-spaced aroylbis­(<i>N</i>,<i>N</i>-diethylthiourea) H₂L³. The compounds {M⊂[Fe₂(L³)₃]}­(PF₆) (M = K⁺, Rb⁺, Tl⁺ or Cs⁺) (<b>9</b>(PF₆)) were prepared by a similar protocol like those with H₂L² with the simultaneous addition of the metal ions to a solution of H₂L³. Due to the larger spacer between the aroylthiourea units, the coordination number of the central M⁺ ions is 12 by six carbonyl and six ether oxygen atoms. All products were characterized by elemental analysis, IR spectroscopy, and X-ray structure analysis. Cyclic voltammetric studies were carried out with the three representative complexes [Fe₂(L¹)₃], {K⊂[Fe₂(L²)₃]}­(PF₆), and {K⊂[Fe₂(L³)₃]}­(PF₆). The obtained voltammograms indicate the dependence of the redox properties of the oligonuclear systems on the conjugation in the organic backbones of the ligands

New anthracene-based Cu(I) dithiocarbamates as AIEgens

The syntheses and structural characterizations of a series of anthracene-tethered Cu(I) phosphine dithiocarbamate complexes, [CuL(PPh3)2], are described in this article. All complexes were readily prepared from corresponding ligands with various acyclic and cyclic N-alkyl substituents and [Cu(PPh3)2(NO3)]. Steric hindrance imposed on the anthracenyl rings by dithiocarbamate, N-alkyl substituents and triphenylphosphine moieties in complexes 1-6 are not detected, as evidenced by the sharp aromatic resonances in 1H NMR spectra. X-ray crystallography reveals distorted tetrahedral chelation environments around the Cu(I) centers in 2 and 3 as well as extensive C–S···π and C–H···π intermolecular interactions in their solid state packings. The complexes display characteristic anthracene-based absorption and emission properties. The emission quantum yields of the complexes are poor (1.0–2.7 × 10−2) but the aggregation-induced emission effects are perceived in aqueous DMSO solutions. Especially, 6 with N-substituted cyclohexyl group displays the largest increase in emission intensity (ca. 7 times).</p