The ³[ndσ*(n+1)pσ] Emissions of Linear Silver(I) and Gold(I) Chains with Bridging Phosphine Ligands

Abstract

The complexes [Au(3)(dcmp)(2)][X](3) {dcmp=bis(dicyclohexylphosphinomethyl)cyclohexylphosphine; X=Cl(-) (1), ClO(4) (-) (2), OTf(-) (3), PF(6) (-) (4), SCN(-)(5)}, [Ag(3)(dcmp)(2)][ClO(4)](3) (6), and [Ag(3)(dcmp)(2)Cl(2)][ClO(4)] (7) were prepared and their structures were determined by X-ray crystallography. Complexes 2-4 display a high-energy emission band with lambda(max) at 442-452 nm, whereas 1 and 5 display a low-energy emission with lambda(max) at 558-634 nm in both solid state and in dichloromethane at 298 K. The former is assigned to the (3)[5dsigma*6psigma] excited state of [Au(3)(dcmp)(2)](3+), whereas the latter is attributed to an exciplex formed between the (3)[5dsigma*6psigma] excited state of [Au(3)(dcmp)(2)](3+) and the counterions. In solid state, complex [Ag(3)(dcmp)(2)][ClO(4)](3) (6) displays an intense emission band at 375 nm with a Stokes shift of approximately 7200 cm(-1) from the (1)[4dsigma*-->5psigma] absorption band at 295 nm. The 375 nm emission band is assigned to the emission directly from the (3)[4dsigma(*)5psigma] excited state of 6. Density functional theory (DFT) calculations revealed that the absorption and emission energies are inversely proportional to the number of metal ions (n) in polynuclear Au(I) and Ag(I) linear chain complexes without close metalanion contacts. The emission energies are extrapolated to be 715 and 446 nm for the infinite linear Au(I) and Ag(I) chains, respectively, at metalmetal distances of about 2.93-3.02 A. A QM/MM calculation on the model [Au(3)(dcmp)(2)Cl(2)](+) system, with Au...Cl contacts of 2.90-3.10 A, gave optimized Au...Au distances of 2.99-3.11 A in its lowest triplet excited state and the emission energies were calculated to be at approximately 600-690 nm, which are assigned to a three-coordinate Au(I) site with its spectroscopic properties affected by Au(I)...Au(I) interactions.

Silver(I) Clusters with Carba‐closo‐dodecaboranylethynyl Ligands: Synthesis, Structure, and Phosphorescence

“…Am ore-detailed analysisa nd comparison to the properties of copper(I) clusters [4,20,22,23] indicated that the emitting states are clustercentered ( 3 CC) in nature and that the pyridine derivatives have no influence on the energy of the excited states. [4,20,21,24] The exceptional properties of the silver(I)c lusters with carba-closo-dodecaboranylethynyll igands are related to the boron-based ligand that, in conjunction with pyridine derivatives, favors the formation of clusters with Ag I 6 or Ag I 7 cores. Thus, the specific structural features of the clustera ppeared to be responsible for the phosphorescence efficiency:p entagonal bipyramidal cluster 4 showed aq uantum yield of 0.76, which is unprecedented for silver(I) clusters.…”

Highly Luminescent Linear Complex Arrays of up to Eight Cuprous Centers

“…[50] Both spectroscopica nd computational resultss howd ecreasing emission energies in the order of Au 2 > Au 3 > Au 4 in similar linear complex arrangements. [51,52] Thus, the observed red-shifted emission and increased lifetimei nc omplex 2 with respect to complex 1 suggest that an increased number of Cu I ···Cu I contacts reduces the HOMO-LUMO gap. This is consistent with the BP86/BSI calculations that reveal ad ecreasei nt he HOMO-LUMO gap of 2.94 kcal mol À1 .T he HOMO of both complexes 1 and 2 (see FiguresS13 and S14 in the Supporting Information, respectively) is dominated by Cu-Cu s*i nteractions delocalized across all of the linearly arranged Cu I atoms.H owever,t he orbital character of the LUMO for complex 1 differs from that of complex 2 (see Figures S13 and S14 in the Supporting Information, respectively).…”

Mono-, di-, and tri-nuclear gold(I) complexes with dansyl moiety: Synthesis, characterization, and photophysical properties

“…Table 1 shows the selected bond distances as well as bond angles of 2 and 3. In 2, the geometry at the gold atom is close to linearity (178.79(12)°and 174.60 (12)°for N(1)\Au(1)\P(1) and N(1)\Au(2)\P(2), respectively). Two gold Inorganic Chemistry Communications 14 (2011Communications 14 ( ) 1436Communications 14 ( -1439 atoms are bridged by a nitrogen atom with the Au(1)\N(1)\Au(2) angle of 114.15 (19)°.…”

“…We have a long-term interest in studying the lowest-lying emissive excited states of metal complexes with d 10 configuration [10][11][12][13]. In view of the isolobal concept [14], in which Ph 3 PAu + is isolobal to H + , we envisaged that if the proton (or protons) of dansylamide (5-dimethylamino-naphthalene-1-sulfonamide) can be replaced by Ph 3 PAu + , it would be interesting to study the luminescence properties of the "gilded" dansylamides.…”

“…It exhibits intense absorption in the UV region and emits in the visible regime with high fluorescence quantum yield as well as high resistance to photo-bleaching. In addition, its modification can be easily carried out by organic synthesis [7][8][9].We have a long-term interest in studying the lowest-lying emissive excited states of metal complexes with d 10 configuration [10][11][12][13]. In view of the isolobal concept [14], in which Ph 3 PAu + is isolobal to H + , we envisaged that if the proton (or protons) of dansylamide (5-dimethylamino-naphthalene-1-sulfonamide) can be replaced by Ph 3 PAu + , it would be interesting to study the luminescence properties of the "gilded" dansylamides.…”