ABSTRACT
Superstructures, combining nanoscopic constituents into micrometer-size assemblies, have a great potential for utilization of the size-dependent quantum-confinement properties in multifunctional electronic and optoelectronic devices. Two diverse superstructures of nanoscopic CdSe were prepared using solvothermal conversion of the same cadmium selenophenolate precursor (Me4N)2[Cd(SePh)4]: the first is a superlattice of monodisperse [Cd54Se32(SePh)48(dmf)4]4- nanoclusters; the second is a unique porous CdSe crystal. Nanoclusters were crystallized as cubic crystals (≤0.5 mm in size) after solvothermal treatment at 200 °C in DMF. UV-vis absorption and PLE spectra of the reported nanoclusters are consistent with previously established trends for the known families of tetrahedral CdSe frameworks. In contrast to these, results of PL spectra are rather unexpected, as distinct room temperature emission is observed both in solution and in the solid state. The porous CdSe crystals were isolated as red hexagonal prisms (≤70 µm in size) via solvothermal treatment under similar conditions but with the addition of an alkylammonium salt. The presence of a three-dimensional CdSe network having a coherent crystalline structure inside hexagonal prisms was concluded based on powder X-ray diffraction, selected area electron diffraction and electron microscopy imaging. Self-assembly via oriented attachment of crystalline nanoparticles is discussed as the most probable mechanism of formation.
ABSTRACT
The first examples of gold(I) trimethylsilylchalcogenolate complexes were synthesized and their reactivity showcased in the preparation of a novel gold-copper-sulfur cluster [Au4 Cu4 S4 (dppm)2 ] (dppm=bis(diphenylphosphino)methane). The unprecedented structural chemistry of this compound gives rise to interesting optoelectronic properties, including long-lived orange luminescence in the solid state. Through time-dependent density functional theory calculations, this emission is shown to originate from ligand-to-metal charge transfer facilitated by Auâ â â Cu metallophilic bonding.
ABSTRACT
As a part of efforts to prepare new "metallachalcogenolate" precursors and develop their chemistry for the formation of ternary mixed-metal chalcogenide nanoclusters, two sets of thermally stable, N-heterocyclic carbene metal-chalcogenolate complexes of the general formula [(IPr)Ag-ESiMe3] (IPr=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene; E=S, 1; Se, 2) and [(iPr2-bimy)Cu-ESiMe3]2 (iPr2-bimy=1,3-diisopropylbenzimidazolin-2-ylidene; E=S, 4; Se, 5) are reported. These are prepared from the reaction between the corresponding carbene metal acetate, [(IPr)AgOAc] and [(iPr-bimy)CuOAc] respectively, and E(SiMe3 )2 at low temperature. The reaction of [(IPr)Ag-ESiMe3] 1 with mercury(II) acetate affords the heterometallic complex [{(IPr)AgS}2Hg] 3 containing two (IPr)Ag-S(-) fragments bonded to a central Hg(II), representing a mixed mercury-silver sulfide complex. The reaction of [(iPr2-bimy)Cu-SSiMe3]2, which contains a smaller N-heterocyclic-carbene, with mercuric(II) acetate affords the high nuclearity cluster, [(iPr2-bimy)6Cu10S8Hg3]6. The new N-heterocyclic carbene metal-chalcogenolate complexes 1, 2, 4, 5 and the ternary mixed-metal chalcogenolate complex 3 and cluster 6 have been characterized by multinuclear NMR spectroscopy ((1)H and (13)C), elemental analysis and single-crystal X-ray diffraction.
