Olga Crespo

The Structural Diversity Triggered by Intermolecular Interactions between AuIS2 Groups: Aurophilia and Beyond

The present study is aimed at elucidating the factors that direct the assembly of a specific family of Au(I) species. The assembly of Au(I) centers and dithiocarboxylato or xanthato ligands results in a surprising structural diversity observed by single-crystal X-ray diffraction. However, in solution, just evidences for discrete bimetallic [Au(2)L(2)] species have been observed. Interestingly, when dithiocarboxylato ligands have been used, a reversible supramolecular assembly has been observed forming the supramolecules of formulae [Au(2)L(2)](2) and [Au(2)L(2)](3). Initial studies on luminescent properties have been carried out at variable temperature. All the compounds show red emissions in the solid state at very similar energies, suggesting that the intramolecular interactions play a more relevant role in the luminescent properties than the intermolecular ones. The computational studies indicate that not only Au···Au interactions, but also Au···S and S···S ones play a role in the structure and energetic of the supramolecular species, as well as for the choice between supramolecular association or intramolecular oligomerization.

Luminescent Silver(I) and Copper(I) Systems Containing Pyridyl Phosphine Bridges

Luminescent silver(I) and copper(I) complexes containing pyridylphosphine ligands have been synthesized and structurally characterized by single crystal X-ray diffraction methods. The reaction of Ag(OTf) (OTf = trifluoromethanesulfonate) with 2-pyridyldiphenylphosphine in different molar ratios gives the species [Ag2(OTf)2(μ-PPh2py)2] (1), [Ag(PPh2py)2]OTf (2), [Ag(PPh2py)3]OTf (3), and [Ag2(PPh2py)3](OTf)2 (4) with several modes of coordination of the pyridylphosphine. The oxidation of the phosphine in compound 4 gave [Ag2(OTf)(μ-PPh2py)2(OPPh2py)]OTf (5) which has been structurally characterized. It shows two bridging phosphine ligands and one chelating OPPh2py ligand. The reactions of the silver salt with bis(2-pyridyl)phenylphosphine in different molar ratios affords the complex [Ag2(OTf)2(μ-PPhpy2)2] (6), while the corresponding reactions with [Cu(NCMe)4]PF6 lead to two different compounds, namely [Cu2(NCMe)2(μ-PPhpy2)2](PF6)2 (7) and [Cu2(PPhpy2)2(μ-PPhpy2)2](PF6)2 (8). All complexes exhibit luminescence in the solid state at room temperature and at 77 K Graphical Abstract Luminescent Silver(I) and Copper(I) Systems Containing Pyridyl Phosphine Bridges

Highly emissive dinuclear complexes [Au2{μ-(PPh2)2C2B9H10}(C6F5)(PR3)] with different gold fragments coordinated to an anionic diphosphine

Reaction of the yellow-green emitters [Au{(PPh(2))(2)C(2)B(9)H(10)}(PR(3))] with [Au(C(6)F(5))(tht)] affords orange-red emissive gold complexes [Au(2){μ-(PPh(2))(2)C(2)B(9)H(10)}(C(6)F(5))(PR(3))] which contain different neutral (PR(3)) and anionic (C(6)F(5)) auxiliary ligands and an anionic diphosphine. The resulting complexes are among the few reported in which an ortho-carborane diphosphine acts in a bridging mode, and are unique in containing not a closo- (neutral), but a nido-carborane (anionic) cluster. DFT and TDDFT calculations led to the prediction of the origin of the two first singlet-triplet transitions, which is consistent with the experimental results. Although the blue emissive nido-diphosphine plays a key role in the transitions of the three-coordinate precursors and the final dinuclear complexes, it is the environment around the gold centre that controls the emission energy.

Decisive Influence of the Metal in Multifunctional Gold, Silver, and Copper Metallacycles: High Quantum Yield Phosphorescence, Color Switching, and Liquid Crystalline Behavior

Three cyclic trinuclear pyrazolate complexes with Au(I), Ag(I), or Cu(I) have been studied. These complexes have interesting and distinct optical and thermal properties depending on the metal, namely, liquid crystalline behavior, red or deep-red phosphorescence at room temperature, thermoluminochromism, and response to silver ions. The selected ligand, 4-hexyl-3,5-dimethylpyrazolate, maximizes the effect that the nature of the metals has on the properties of the complexes, thus allowing the intermolecular metallophilic interactions to be responsible for the optical properties. Moreover, the gold and silver complexes show columnar liquid crystal phases at high temperature. All of the complexes have good solubility properties for processing as poly(methyl methacrylate) (PMMA) doped films. Films of the gold, silver, and copper complexes show interesting optical behavior such as wide-range color switching or phosphorescence turn-on upon cooling. In addition, films of the gold complex show a bright color switching (red to blue) in the presence of silver ions. The gold and copper complexes are bright phosphors with phosphorescent quantum yields of 90% in PMMA films, the highest values reported for this class of compounds at room temperature.